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Wikipedia

Mathematical optimization

Mathematical optimization (alternatively spelled optimisation) or mathematical programming is the selection of a best element, with regard to some criterion, from some set of available alternatives.[1] It is generally divided into two subfields: discrete optimization and continuous optimization. Optimization problems arise in all quantitative disciplines from computer science and engineering[2] to operations research and economics, and the development of solution methods has been of interest in mathematics for centuries.[3]

Graph of a given by z = f(x, y) = −(x² + y²) + 4. The global maximum at (x, y, z) = (0, 0, 4) is indicated by a blue dot.
Nelder-Mead minimum search of Simionescu's function. Simplex vertices are ordered by their values, with 1 having the lowest (fx best) value.

In the more general approach, an optimization problem consists of maximizing or minimizing a real function by systematically choosing input values from within an allowed set and computing the value of the function. The generalization of optimization theory and techniques to other formulations constitutes a large area of applied mathematics. More generally, optimization includes finding "best available" values of some objective function given a defined domain (or input), including a variety of different types of objective functions and different types of domains.

Optimization problems

Optimization problems can be divided into two categories, depending on whether the variables are continuous or discrete:

An optimization problem can be represented in the following way:

Given: a function f : A → ℝ from some set A to the real numbers
Sought: an element x0A such that f(x0) ≤ f(x) for all xA ("minimization") or such that f(x0) ≥ f(x) for all xA ("maximization").

Such a formulation is called an optimization problem or a mathematical programming problem (a term not directly related to computer programming, but still in use for example in linear programming – see History below). Many real-world and theoretical problems may be modeled in this general framework.

Since the following is valid

 

it suffices to solve only minimization problems. However, the opposite perspective of considering only maximization problems would be valid, too.

Problems formulated using this technique in the fields of physics may refer to the technique as energy minimization, speaking of the value of the function f as representing the energy of the system being modeled. In machine learning, it is always necessary to continuously evaluate the quality of a data model by using a cost function where a minimum implies a set of possibly optimal parameters with an optimal (lowest) error.

Typically, A is some subset of the Euclidean space n, often specified by a set of constraints, equalities or inequalities that the members of A have to satisfy. The domain A of f is called the search space or the choice set, while the elements of A are called candidate solutions or feasible solutions.

The function f is called, variously, an objective function, a loss function or cost function (minimization),[4] a utility function or fitness function (maximization), or, in certain fields, an energy function or energy functional. A feasible solution that minimizes (or maximizes, if that is the goal) the objective function is called an optimal solution.

In mathematics, conventional optimization problems are usually stated in terms of minimization.

A local minimum x* is defined as an element for which there exists some δ > 0 such that

 

the expression f(x*) ≤ f(x) holds;

that is to say, on some region around x* all of the function values are greater than or equal to the value at that element. Local maxima are defined similarly.

While a local minimum is at least as good as any nearby elements, a global minimum is at least as good as every feasible element. Generally, unless the objective function is convex in a minimization problem, there may be several local minima. In a convex problem, if there is a local minimum that is interior (not on the edge of the set of feasible elements), it is also the global minimum, but a nonconvex problem may have more than one local minimum not all of which need be global minima.

A large number of algorithms proposed for solving the nonconvex problems – including the majority of commercially available solvers – are not capable of making a distinction between locally optimal solutions and globally optimal solutions, and will treat the former as actual solutions to the original problem. Global optimization is the branch of applied mathematics and numerical analysis that is concerned with the development of deterministic algorithms that are capable of guaranteeing convergence in finite time to the actual optimal solution of a nonconvex problem.

Notation

Optimization problems are often expressed with special notation. Here are some examples:

Minimum and maximum value of a function

Consider the following notation:

 

This denotes the minimum value of the objective function x2 + 1, when choosing x from the set of real numbers . The minimum value in this case is 1, occurring at x = 0.

Similarly, the notation

 

asks for the maximum value of the objective function 2x, where x may be any real number. In this case, there is no such maximum as the objective function is unbounded, so the answer is "infinity" or "undefined".

Optimal input arguments

Consider the following notation:

 

or equivalently

 

This represents the value (or values) of the argument x in the interval (−∞,−1] that minimizes (or minimises) the objective function x2 + 1 (the actual minimum value of that function is not what the problem asks for). In this case, the answer is x = −1, since x = 0 is infeasible, that is, it does not belong to the feasible set.

Similarly,

 

or equivalently

 

represents the {x, y} pair (or pairs) that maximizes (or maximize) the value of the objective function x cos y, with the added constraint that x lie in the interval [−5,5] (again, the actual maximum value of the expression does not matter). In this case, the solutions are the pairs of the form {5, 2kπ} and {−5, (2k + 1)π}, where k ranges over all integers.

Operators arg min and arg max are sometimes also written as argmin and argmax, and stand for argument of the minimum and argument of the maximum.

History

Fermat and Lagrange found calculus-based formulae for identifying optima, while Newton and Gauss proposed iterative methods for moving towards an optimum.

The term "linear programming" for certain optimization cases was due to George B. Dantzig, although much of the theory had been introduced by Leonid Kantorovich in 1939. (Programming in this context does not refer to computer programming, but comes from the use of program by the United States military to refer to proposed training and logistics schedules, which were the problems Dantzig studied at that time.) Dantzig published the Simplex algorithm in 1947, and John von Neumann developed the theory of duality in the same year.[citation needed]

Other notable researchers in mathematical optimization include the following:

Major subfields

  • Convex programming studies the case when the objective function is convex (minimization) or concave (maximization) and the constraint set is convex. This can be viewed as a particular case of nonlinear programming or as generalization of linear or convex quadratic programming.
    • Linear programming (LP), a type of convex programming, studies the case in which the objective function f is linear and the constraints are specified using only linear equalities and inequalities. Such a constraint set is called a polyhedron or a polytope if it is bounded.
    • Second-order cone programming (SOCP) is a convex program, and includes certain types of quadratic programs.
    • Semidefinite programming (SDP) is a subfield of convex optimization where the underlying variables are semidefinite matrices. It is a generalization of linear and convex quadratic programming.
    • Conic programming is a general form of convex programming. LP, SOCP and SDP can all be viewed as conic programs with the appropriate type of cone.
    • Geometric programming is a technique whereby objective and inequality constraints expressed as posynomials and equality constraints as monomials can be transformed into a convex program.
  • Integer programming studies linear programs in which some or all variables are constrained to take on integer values. This is not convex, and in general much more difficult than regular linear programming.
  • Quadratic programming allows the objective function to have quadratic terms, while the feasible set must be specified with linear equalities and inequalities. For specific forms of the quadratic term, this is a type of convex programming.
  • Fractional programming studies optimization of ratios of two nonlinear functions. The special class of concave fractional programs can be transformed to a convex optimization problem.
  • Nonlinear programming studies the general case in which the objective function or the constraints or both contain nonlinear parts. This may or may not be a convex program. In general, whether the program is convex affects the difficulty of solving it.
  • Stochastic programming studies the case in which some of the constraints or parameters depend on random variables.
  • Robust optimization is, like stochastic programming, an attempt to capture uncertainty in the data underlying the optimization problem. Robust optimization aims to find solutions that are valid under all possible realizations of the uncertainties defined by an uncertainty set.
  • Combinatorial optimization is concerned with problems where the set of feasible solutions is discrete or can be reduced to a discrete one.
  • Stochastic optimization is used with random (noisy) function measurements or random inputs in the search process.
  • Infinite-dimensional optimization studies the case when the set of feasible solutions is a subset of an infinite-dimensional space, such as a space of functions.
  • Heuristics and metaheuristics make few or no assumptions about the problem being optimized. Usually, heuristics do not guarantee that any optimal solution need be found. On the other hand, heuristics are used to find approximate solutions for many complicated optimization problems.
  • Constraint satisfaction studies the case in which the objective function f is constant (this is used in artificial intelligence, particularly in automated reasoning).
    • Constraint programming is a programming paradigm wherein relations between variables are stated in the form of constraints.
  • Disjunctive programming is used where at least one constraint must be satisfied but not all. It is of particular use in scheduling.
  • Space mapping is a concept for modeling and optimization of an engineering system to high-fidelity (fine) model accuracy exploiting a suitable physically meaningful coarse or surrogate model.

In a number of subfields, the techniques are designed primarily for optimization in dynamic contexts (that is, decision making over time):

Multi-objective optimization

Adding more than one objective to an optimization problem adds complexity. For example, to optimize a structural design, one would desire a design that is both light and rigid. When two objectives conflict, a trade-off must be created. There may be one lightest design, one stiffest design, and an infinite number of designs that are some compromise of weight and rigidity. The set of trade-off designs that improve upon one criterion at the expense of another is known as the Pareto set. The curve created plotting weight against stiffness of the best designs is known as the Pareto frontier.

A design is judged to be "Pareto optimal" (equivalently, "Pareto efficient" or in the Pareto set) if it is not dominated by any other design: If it is worse than another design in some respects and no better in any respect, then it is dominated and is not Pareto optimal.

The choice among "Pareto optimal" solutions to determine the "favorite solution" is delegated to the decision maker. In other words, defining the problem as multi-objective optimization signals that some information is missing: desirable objectives are given but combinations of them are not rated relative to each other. In some cases, the missing information can be derived by interactive sessions with the decision maker.

Multi-objective optimization problems have been generalized further into vector optimization problems where the (partial) ordering is no longer given by the Pareto ordering.

Multi-modal or global optimization

Optimization problems are often multi-modal; that is, they possess multiple good solutions. They could all be globally good (same cost function value) or there could be a mix of globally good and locally good solutions. Obtaining all (or at least some of) the multiple solutions is the goal of a multi-modal optimizer.

Classical optimization techniques due to their iterative approach do not perform satisfactorily when they are used to obtain multiple solutions, since it is not guaranteed that different solutions will be obtained even with different starting points in multiple runs of the algorithm.

Common approaches to global optimization problems, where multiple local extrema may be present include evolutionary algorithms, Bayesian optimization and simulated annealing.

Classification of critical points and extrema

Feasibility problem

The satisfiability problem, also called the feasibility problem, is just the problem of finding any feasible solution at all without regard to objective value. This can be regarded as the special case of mathematical optimization where the objective value is the same for every solution, and thus any solution is optimal.

Many optimization algorithms need to start from a feasible point. One way to obtain such a point is to relax the feasibility conditions using a slack variable; with enough slack, any starting point is feasible. Then, minimize that slack variable until the slack is null or negative.

Existence

The extreme value theorem of Karl Weierstrass states that a continuous real-valued function on a compact set attains its maximum and minimum value. More generally, a lower semi-continuous function on a compact set attains its minimum; an upper semi-continuous function on a compact set attains its maximum point or view.

Necessary conditions for optimality

One of Fermat's theorems states that optima of unconstrained problems are found at stationary points, where the first derivative or the gradient of the objective function is zero (see first derivative test). More generally, they may be found at critical points, where the first derivative or gradient of the objective function is zero or is undefined, or on the boundary of the choice set. An equation (or set of equations) stating that the first derivative(s) equal(s) zero at an interior optimum is called a 'first-order condition' or a set of first-order conditions.

Optima of equality-constrained problems can be found by the Lagrange multiplier method. The optima of problems with equality and/or inequality constraints can be found using the 'Karush–Kuhn–Tucker conditions'.

Sufficient conditions for optimality

While the first derivative test identifies points that might be extrema, this test does not distinguish a point that is a minimum from one that is a maximum or one that is neither. When the objective function is twice differentiable, these cases can be distinguished by checking the second derivative or the matrix of second derivatives (called the Hessian matrix) in unconstrained problems, or the matrix of second derivatives of the objective function and the constraints called the bordered Hessian in constrained problems. The conditions that distinguish maxima, or minima, from other stationary points are called 'second-order conditions' (see 'Second derivative test'). If a candidate solution satisfies the first-order conditions, then the satisfaction of the second-order conditions as well is sufficient to establish at least local optimality.

Sensitivity and continuity of optima

The envelope theorem describes how the value of an optimal solution changes when an underlying parameter changes. The process of computing this change is called comparative statics.

The maximum theorem of Claude Berge (1963) describes the continuity of an optimal solution as a function of underlying parameters.

Calculus of optimization

For unconstrained problems with twice-differentiable functions, some critical points can be found by finding the points where the gradient of the objective function is zero (that is, the stationary points). More generally, a zero subgradient certifies that a local minimum has been found for minimization problems with convex functions and other locally Lipschitz functions.

Further, critical points can be classified using the definiteness of the Hessian matrix: If the Hessian is positive definite at a critical point, then the point is a local minimum; if the Hessian matrix is negative definite, then the point is a local maximum; finally, if indefinite, then the point is some kind of saddle point.

Constrained problems can often be transformed into unconstrained problems with the help of Lagrange multipliers. Lagrangian relaxation can also provide approximate solutions to difficult constrained problems.

When the objective function is a convex function, then any local minimum will also be a global minimum. There exist efficient numerical techniques for minimizing convex functions, such as interior-point methods.

Global convergence

More generally, if the objective function is not a quadratic function, then many optimization methods use other methods to ensure that some subsequence of iterations converges to an optimal solution. The first and still popular method for ensuring convergence relies on line searches, which optimize a function along one dimension. A second and increasingly popular method for ensuring convergence uses trust regions. Both line searches and trust regions are used in modern methods of non-differentiable optimization. Usually, a global optimizer is much slower than advanced local optimizers (such as BFGS), so often an efficient global optimizer can be constructed by starting the local optimizer from different starting points.

Computational optimization techniques

To solve problems, researchers may use algorithms that terminate in a finite number of steps, or iterative methods that converge to a solution (on some specified class of problems), or heuristics that may provide approximate solutions to some problems (although their iterates need not converge).

Optimization algorithms

Iterative methods

The iterative methods used to solve problems of nonlinear programming differ according to whether they evaluate Hessians, gradients, or only function values. While evaluating Hessians (H) and gradients (G) improves the rate of convergence, for functions for which these quantities exist and vary sufficiently smoothly, such evaluations increase the computational complexity (or computational cost) of each iteration. In some cases, the computational complexity may be excessively high.

One major criterion for optimizers is just the number of required function evaluations as this often is already a large computational effort, usually much more effort than within the optimizer itself, which mainly has to operate over the N variables. The derivatives provide detailed information for such optimizers, but are even harder to calculate, e.g. approximating the gradient takes at least N+1 function evaluations. For approximations of the 2nd derivatives (collected in the Hessian matrix), the number of function evaluations is in the order of N². Newton's method requires the 2nd-order derivatives, so for each iteration, the number of function calls is in the order of N², but for a simpler pure gradient optimizer it is only N. However, gradient optimizers need usually more iterations than Newton's algorithm. Which one is best with respect to the number of function calls depends on the problem itself.

  • Methods that evaluate Hessians (or approximate Hessians, using finite differences):
    • Newton's method
    • Sequential quadratic programming: A Newton-based method for small-medium scale constrained problems. Some versions can handle large-dimensional problems.
    • Interior point methods: This is a large class of methods for constrained optimization, some of which use only (sub)gradient information and others of which require the evaluation of Hessians.
  • Methods that evaluate gradients, or approximate gradients in some way (or even subgradients):
    • Coordinate descent methods: Algorithms which update a single coordinate in each iteration
    • Conjugate gradient methods: Iterative methods for large problems. (In theory, these methods terminate in a finite number of steps with quadratic objective functions, but this finite termination is not observed in practice on finite–precision computers.)
    • Gradient descent (alternatively, "steepest descent" or "steepest ascent"): A (slow) method of historical and theoretical interest, which has had renewed interest for finding approximate solutions of enormous problems.
    • Subgradient methods: An iterative method for large locally Lipschitz functions using generalized gradients. Following Boris T. Polyak, subgradient–projection methods are similar to conjugate–gradient methods.
    • Bundle method of descent: An iterative method for small–medium-sized problems with locally Lipschitz functions, particularly for convex minimization problems (similar to conjugate gradient methods).
    • Ellipsoid method: An iterative method for small problems with quasiconvex objective functions and of great theoretical interest, particularly in establishing the polynomial time complexity of some combinatorial optimization problems. It has similarities with Quasi-Newton methods.
    • Conditional gradient method (Frank–Wolfe) for approximate minimization of specially structured problems with linear constraints, especially with traffic networks. For general unconstrained problems, this method reduces to the gradient method, which is regarded as obsolete (for almost all problems).
    • Quasi-Newton methods: Iterative methods for medium-large problems (e.g. N<1000).
    • Simultaneous perturbation stochastic approximation (SPSA) method for stochastic optimization; uses random (efficient) gradient approximation.
  • Methods that evaluate only function values: If a problem is continuously differentiable, then gradients can be approximated using finite differences, in which case a gradient-based method can be used.

Heuristics

Besides (finitely terminating) algorithms and (convergent) iterative methods, there are heuristics. A heuristic is any algorithm which is not guaranteed (mathematically) to find the solution, but which is nevertheless useful in certain practical situations. List of some well-known heuristics:

Applications

Mechanics

Problems in rigid body dynamics (in particular articulated rigid body dynamics) often require mathematical programming techniques, since you can view rigid body dynamics as attempting to solve an ordinary differential equation on a constraint manifold;[5] the constraints are various nonlinear geometric constraints such as "these two points must always coincide", "this surface must not penetrate any other", or "this point must always lie somewhere on this curve". Also, the problem of computing contact forces can be done by solving a linear complementarity problem, which can also be viewed as a QP (quadratic programming) problem.

Many design problems can also be expressed as optimization programs. This application is called design optimization. One subset is the engineering optimization, and another recent and growing subset of this field is multidisciplinary design optimization, which, while useful in many problems, has in particular been applied to aerospace engineering problems.

This approach may be applied in cosmology and astrophysics.[6]

Economics and finance

Economics is closely enough linked to optimization of agents that an influential definition relatedly describes economics qua science as the "study of human behavior as a relationship between ends and scarce means" with alternative uses.[7] Modern optimization theory includes traditional optimization theory but also overlaps with game theory and the study of economic equilibria. The Journal of Economic Literature codes classify mathematical programming, optimization techniques, and related topics under JEL:C61-C63.

In microeconomics, the utility maximization problem and its dual problem, the expenditure minimization problem, are economic optimization problems. Insofar as they behave consistently, consumers are assumed to maximize their utility, while firms are usually assumed to maximize their profit. Also, agents are often modeled as being risk-averse, thereby preferring to avoid risk. Asset prices are also modeled using optimization theory, though the underlying mathematics relies on optimizing stochastic processes rather than on static optimization. International trade theory also uses optimization to explain trade patterns between nations. The optimization of portfolios is an example of multi-objective optimization in economics.

Since the 1970s, economists have modeled dynamic decisions over time using control theory.[8] For example, dynamic search models are used to study labor-market behavior.[9] A crucial distinction is between deterministic and stochastic models.[10] Macroeconomists build dynamic stochastic general equilibrium (DSGE) models that describe the dynamics of the whole economy as the result of the interdependent optimizing decisions of workers, consumers, investors, and governments.[11][12]

Electrical engineering

Some common applications of optimization techniques in electrical engineering include active filter design,[13] stray field reduction in superconducting magnetic energy storage systems, space mapping design of microwave structures,[14] handset antennas,[15][16][17] electromagnetics-based design. Electromagnetically validated design optimization of microwave components and antennas has made extensive use of an appropriate physics-based or empirical surrogate model and space mapping methodologies since the discovery of space mapping in 1993.[18][19]

Civil engineering

Optimization has been widely used in civil engineering. Construction management and transportation engineering are among the main branches of civil engineering that heavily rely on optimization. The most common civil engineering problems that are solved by optimization are cut and fill of roads, life-cycle analysis of structures and infrastructures,[20] resource leveling,[21][22] water resource allocation, traffic management[23] and schedule optimization.

Operations research

Another field that uses optimization techniques extensively is operations research.[24] Operations research also uses stochastic modeling and simulation to support improved decision-making. Increasingly, operations research uses stochastic programming to model dynamic decisions that adapt to events; such problems can be solved with large-scale optimization and stochastic optimization methods.

Control engineering

Mathematical optimization is used in much modern controller design. High-level controllers such as model predictive control (MPC) or real-time optimization (RTO) employ mathematical optimization. These algorithms run online and repeatedly determine values for decision variables, such as choke openings in a process plant, by iteratively solving a mathematical optimization problem including constraints and a model of the system to be controlled.

Geophysics

Optimization techniques are regularly used in geophysical parameter estimation problems. Given a set of geophysical measurements, e.g. seismic recordings, it is common to solve for the physical properties and geometrical shapes of the underlying rocks and fluids. The majority of problems in geophysics are nonlinear with both deterministic and stochastic methods being widely used.

Molecular modeling

Nonlinear optimization methods are widely used in conformational analysis.

Computational systems biology

Optimization techniques are used in many facets of computational systems biology such as model building, optimal experimental design, metabolic engineering, and synthetic biology.[25] Linear programming has been applied to calculate the maximal possible yields of fermentation products,[25] and to infer gene regulatory networks from multiple microarray datasets[26] as well as transcriptional regulatory networks from high-throughput data.[27] Nonlinear programming has been used to analyze energy metabolism[28] and has been applied to metabolic engineering and parameter estimation in biochemical pathways.[29]

Machine learning

Solvers

See also

Notes

  1. ^ "The Nature of Mathematical Programming 2014-03-05 at the Wayback Machine," Mathematical Programming Glossary, INFORMS Computing Society.
  2. ^ Martins, Joaquim R. R. A.; Ning, Andrew (2021-10-01). Engineering Design Optimization. Cambridge University Press. ISBN 978-1108833417.
  3. ^ Du, D. Z.; Pardalos, P. M.; Wu, W. (2008). "History of Optimization". In Floudas, C.; Pardalos, P. (eds.). Encyclopedia of Optimization. Boston: Springer. pp. 1538–1542.
  4. ^ W. Erwin Diewert (2008). "cost functions," The New Palgrave Dictionary of Economics, 2nd Edition Contents.
  5. ^ Vereshchagin, A.F. (1989). "Modelling and control of motion of manipulation robots". Soviet Journal of Computer and Systems Sciences. 27 (5): 29–38.
  6. ^ Haggag, S.; Desokey, F.; Ramadan, M. (2017). "A cosmological inflationary model using optimal control". Gravitation and Cosmology. 23 (3): 236–239. Bibcode:2017GrCo...23..236H. doi:10.1134/S0202289317030069. ISSN 1995-0721. S2CID 125980981.
  7. ^ Lionel Robbins (1935, 2nd ed.) An Essay on the Nature and Significance of Economic Science, Macmillan, p. 16.
  8. ^ Dorfman, Robert (1969). "An Economic Interpretation of Optimal Control Theory". American Economic Review. 59 (5): 817–831. JSTOR 1810679.
  9. ^ Sargent, Thomas J. (1987). "Search". Dynamic Macroeconomic Theory. Harvard University Press. pp. 57–91. ISBN 9780674043084.
  10. ^ A.G. Malliaris (2008). "stochastic optimal control," The New Palgrave Dictionary of Economics, 2nd Edition. Abstract 2017-10-18 at the Wayback Machine.
  11. ^ Rotemberg, Julio; Woodford, Michael (1997). "An Optimization-based Econometric Framework for the Evaluation of Monetary Policy" (PDF). NBER Macroeconomics Annual. 12: 297–346. doi:10.2307/3585236. JSTOR 3585236.
  12. ^ From The New Palgrave Dictionary of Economics (2008), 2nd Edition with Abstract links:
       • "numerical optimization methods in economics" by Karl Schmedders
       • "convex programming" by Lawrence E. Blume
       • "Arrow–Debreu model of general equilibrium" by John Geanakoplos.
  13. ^ De, Bishnu Prasad; Kar, R.; Mandal, D.; Ghoshal, S.P. (2014-09-27). "Optimal selection of components value for analog active filter design using simplex particle swarm optimization". International Journal of Machine Learning and Cybernetics. 6 (4): 621–636. doi:10.1007/s13042-014-0299-0. ISSN 1868-8071. S2CID 13071135.
  14. ^ Koziel, Slawomir; Bandler, John W. (January 2008). "Space Mapping With Multiple Coarse Models for Optimization of Microwave Components". IEEE Microwave and Wireless Components Letters. 18 (1): 1–3. CiteSeerX 10.1.1.147.5407. doi:10.1109/LMWC.2007.911969. S2CID 11086218.
  15. ^ Tu, Sheng; Cheng, Qingsha S.; Zhang, Yifan; Bandler, John W.; Nikolova, Natalia K. (July 2013). "Space Mapping Optimization of Handset Antennas Exploiting Thin-Wire Models". IEEE Transactions on Antennas and Propagation. 61 (7): 3797–3807. Bibcode:2013ITAP...61.3797T. doi:10.1109/TAP.2013.2254695.
  16. ^ N. Friedrich, “Space mapping outpaces EM optimization in handset-antenna design,” microwaves&rf, August 30, 2013.
  17. ^ Cervantes-González, Juan C.; Rayas-Sánchez, José E.; López, Carlos A.; Camacho-Pérez, José R.; Brito-Brito, Zabdiel; Chávez-Hurtado, José L. (February 2016). "Space mapping optimization of handset antennas considering EM effects of mobile phone components and human body". International Journal of RF and Microwave Computer-Aided Engineering. 26 (2): 121–128. doi:10.1002/mmce.20945. S2CID 110195165.
  18. ^ Bandler, J.W.; Biernacki, R.M.; Chen, Shao Hua; Grobelny, P.A.; Hemmers, R.H. (1994). "Space mapping technique for electromagnetic optimization". IEEE Transactions on Microwave Theory and Techniques. 42 (12): 2536–2544. Bibcode:1994ITMTT..42.2536B. doi:10.1109/22.339794.
  19. ^ Bandler, J.W.; Biernacki, R.M.; Shao Hua Chen; Hemmers, R.H.; Madsen, K. (1995). "Electromagnetic optimization exploiting aggressive space mapping". IEEE Transactions on Microwave Theory and Techniques. 43 (12): 2874–2882. Bibcode:1995ITMTT..43.2874B. doi:10.1109/22.475649.
  20. ^ Piryonesi, Sayed Madeh; Tavakolan, Mehdi (9 January 2017). "A mathematical programming model for solving cost-safety optimization (CSO) problems in the maintenance of structures". KSCE Journal of Civil Engineering. 21 (6): 2226–2234. doi:10.1007/s12205-017-0531-z. S2CID 113616284.
  21. ^ Hegazy, Tarek (June 1999). "Optimization of Resource Allocation and Leveling Using Genetic Algorithms". Journal of Construction Engineering and Management. 125 (3): 167–175. doi:10.1061/(ASCE)0733-9364(1999)125:3(167).
  22. ^ Piryonesi, S. Madeh; Nasseri, Mehran; Ramezani, Abdollah (9 July 2018). "Piryonesi, S. M., Nasseri, M., & Ramezani, A. (2018). Resource leveling in construction projects with activity splitting and resource constraints: a simulated annealing optimization". Canadian Journal of Civil Engineering. 46: 81–86. doi:10.1139/cjce-2017-0670. hdl:1807/93364. S2CID 116480238.
  23. ^ Herty, M.; Klar, A. (2003-01-01). "Modeling, Simulation, and Optimization of Traffic Flow Networks". SIAM Journal on Scientific Computing. 25 (3): 1066–1087. Bibcode:2003SJSC...25.1066H. doi:10.1137/S106482750241459X. ISSN 1064-8275.
  24. ^ . Archived from the original on 18 December 2014. Retrieved 14 September 2013.
  25. ^ a b Papoutsakis, Eleftherios Terry (February 1984). "Equations and calculations for fermentations of butyric acid bacteria". Biotechnology and Bioengineering. 26 (2): 174–187. doi:10.1002/bit.260260210. ISSN 0006-3592. PMID 18551704. S2CID 25023799.
  26. ^ Wang, Yong; Joshi, Trupti; Zhang, Xiang-Sun; Xu, Dong; Chen, Luonan (2006-07-24). "Inferring gene regulatory networks from multiple microarray datasets". Bioinformatics. 22 (19): 2413–2420. doi:10.1093/bioinformatics/btl396. ISSN 1460-2059. PMID 16864593.
  27. ^ Wang, Rui-Sheng; Wang, Yong; Zhang, Xiang-Sun; Chen, Luonan (2007-09-22). "Inferring transcriptional regulatory networks from high-throughput data". Bioinformatics. 23 (22): 3056–3064. doi:10.1093/bioinformatics/btm465. ISSN 1460-2059. PMID 17890736.
  28. ^ Vo, Thuy D.; Paul Lee, W.N.; Palsson, Bernhard O. (May 2007). "Systems analysis of energy metabolism elucidates the affected respiratory chain complex in Leigh's syndrome". Molecular Genetics and Metabolism. 91 (1): 15–22. doi:10.1016/j.ymgme.2007.01.012. ISSN 1096-7192. PMID 17336115.
  29. ^ Mendes, P.; Kell, D. (1998). "Non-linear optimization of biochemical pathways: applications to metabolic engineering and parameter estimation". Bioinformatics. 14 (10): 869–883. doi:10.1093/bioinformatics/14.10.869. ISSN 1367-4803. PMID 9927716.

Further reading

External links

  • "Decision Tree for Optimization Software". Links to optimization source codes
  • "Global optimization".
  • "EE364a: Convex Optimization I". Course from Stanford University.
  • Varoquaux, Gaël. "Mathematical Optimization: Finding Minima of Functions".

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Mathematical programming redirects here For the peer reviewed journal see Mathematical Programming Optimization and Optimum redirect here For other uses see Optimization disambiguation and Optimum disambiguation Mathematical optimization alternatively spelled optimisation or mathematical programming is the selection of a best element with regard to some criterion from some set of available alternatives 1 It is generally divided into two subfields discrete optimization and continuous optimization Optimization problems arise in all quantitative disciplines from computer science and engineering 2 to operations research and economics and the development of solution methods has been of interest in mathematics for centuries 3 Graph of a given by z f x y x y 4 The global maximum at x y z 0 0 4 is indicated by a blue dot Nelder Mead minimum search of Simionescu s function Simplex vertices are ordered by their values with 1 having the lowest fx best value In the more general approach an optimization problem consists of maximizing or minimizing a real function by systematically choosing input values from within an allowed set and computing the value of the function The generalization of optimization theory and techniques to other formulations constitutes a large area of applied mathematics More generally optimization includes finding best available values of some objective function given a defined domain or input including a variety of different types of objective functions and different types of domains Contents 1 Optimization problems 2 Notation 2 1 Minimum and maximum value of a function 2 2 Optimal input arguments 3 History 4 Major subfields 4 1 Multi objective optimization 4 2 Multi modal or global optimization 5 Classification of critical points and extrema 5 1 Feasibility problem 5 2 Existence 5 3 Necessary conditions for optimality 5 4 Sufficient conditions for optimality 5 5 Sensitivity and continuity of optima 5 6 Calculus of optimization 5 7 Global convergence 6 Computational optimization techniques 6 1 Optimization algorithms 6 2 Iterative methods 6 3 Heuristics 7 Applications 7 1 Mechanics 7 2 Economics and finance 7 3 Electrical engineering 7 4 Civil engineering 7 5 Operations research 7 6 Control engineering 7 7 Geophysics 7 8 Molecular modeling 7 9 Computational systems biology 7 10 Machine learning 8 Solvers 9 See also 10 Notes 11 Further reading 12 External linksOptimization problems EditMain article Optimization problem Optimization problems can be divided into two categories depending on whether the variables are continuous or discrete An optimization problem with discrete variables is known as a discrete optimization in which an object such as an integer permutation or graph must be found from a countable set A problem with continuous variables is known as a continuous optimization in which an optimal value from a continuous function must be found They can include constrained problems and multimodal problems An optimization problem can be represented in the following way Given a function f A ℝ from some set A to the real numbers Sought an element x0 A such that f x0 f x for all x A minimization or such that f x0 f x for all x A maximization Such a formulation is called an optimization problem or a mathematical programming problem a term not directly related to computer programming but still in use for example in linear programming see History below Many real world and theoretical problems may be modeled in this general framework Since the following is valid f x 0 f x f x 0 f x displaystyle f mathbf x 0 geq f mathbf x Leftrightarrow f mathbf x 0 leq f mathbf x it suffices to solve only minimization problems However the opposite perspective of considering only maximization problems would be valid too Problems formulated using this technique in the fields of physics may refer to the technique as energy minimization speaking of the value of the function f as representing the energy of the system being modeled In machine learning it is always necessary to continuously evaluate the quality of a data model by using a cost function where a minimum implies a set of possibly optimal parameters with an optimal lowest error Typically A is some subset of the Euclidean space ℝn often specified by a set of constraints equalities or inequalities that the members of A have to satisfy The domain A of f is called the search space or the choice set while the elements of A are called candidate solutions or feasible solutions The function f is called variously an objective function a loss function or cost function minimization 4 a utility function or fitness function maximization or in certain fields an energy function or energy functional A feasible solution that minimizes or maximizes if that is the goal the objective function is called an optimal solution In mathematics conventional optimization problems are usually stated in terms of minimization A local minimum x is defined as an element for which there exists some d gt 0 such that x A where x x d displaystyle forall mathbf x in A text where left Vert mathbf x mathbf x ast right Vert leq delta the expression f x f x holds that is to say on some region around x all of the function values are greater than or equal to the value at that element Local maxima are defined similarly While a local minimum is at least as good as any nearby elements a global minimum is at least as good as every feasible element Generally unless the objective function is convex in a minimization problem there may be several local minima In a convex problem if there is a local minimum that is interior not on the edge of the set of feasible elements it is also the global minimum but a nonconvex problem may have more than one local minimum not all of which need be global minima A large number of algorithms proposed for solving the nonconvex problems including the majority of commercially available solvers are not capable of making a distinction between locally optimal solutions and globally optimal solutions and will treat the former as actual solutions to the original problem Global optimization is the branch of applied mathematics and numerical analysis that is concerned with the development of deterministic algorithms that are capable of guaranteeing convergence in finite time to the actual optimal solution of a nonconvex problem Notation EditOptimization problems are often expressed with special notation Here are some examples Minimum and maximum value of a function Edit Consider the following notation min x R x 2 1 displaystyle min x in mathbb R left x 2 1 right This denotes the minimum value of the objective function x2 1 when choosing x from the set of real numbers ℝ The minimum value in this case is 1 occurring at x 0 Similarly the notation max x R 2 x displaystyle max x in mathbb R 2x asks for the maximum value of the objective function 2x where x may be any real number In this case there is no such maximum as the objective function is unbounded so the answer is infinity or undefined Optimal input arguments Edit Main article Arg max Consider the following notation a r g m i n x 1 x 2 1 displaystyle underset x in infty 1 operatorname arg min x 2 1 or equivalently a r g m i n x x 2 1 subject to x 1 displaystyle underset x operatorname arg min x 2 1 text subject to x in infty 1 This represents the value or values of the argument x in the interval 1 that minimizes or minimises the objective function x2 1 the actual minimum value of that function is not what the problem asks for In this case the answer is x 1 since x 0 is infeasible that is it does not belong to the feasible set Similarly a r g m a x x 5 5 y R x cos y displaystyle underset x in 5 5 y in mathbb R operatorname arg max x cos y or equivalently a r g m a x x y x cos y subject to x 5 5 y R displaystyle underset x y operatorname arg max x cos y text subject to x in 5 5 y in mathbb R represents the x y pair or pairs that maximizes or maximize the value of the objective function x cos y with the added constraint that x lie in the interval 5 5 again the actual maximum value of the expression does not matter In this case the solutions are the pairs of the form 5 2kp and 5 2k 1 p where k ranges over all integers Operators arg min and arg max are sometimes also written as argmin and argmax and stand for argument of the minimum and argument of the maximum History EditFermat and Lagrange found calculus based formulae for identifying optima while Newton and Gauss proposed iterative methods for moving towards an optimum The term linear programming for certain optimization cases was due to George B Dantzig although much of the theory had been introduced by Leonid Kantorovich in 1939 Programming in this context does not refer to computer programming but comes from the use of program by the United States military to refer to proposed training and logistics schedules which were the problems Dantzig studied at that time Dantzig published the Simplex algorithm in 1947 and John von Neumann developed the theory of duality in the same year citation needed Other notable researchers in mathematical optimization include the following Richard Bellman Dimitri Bertsekas Michel Bierlaire Roger Fletcher Ronald A Howard Fritz John Narendra Karmarkar William Karush Leonid Khachiyan Bernard Koopman Harold Kuhn Laszlo Lovasz Arkadi Nemirovski Yurii Nesterov Lev Pontryagin R Tyrrell Rockafellar Naum Z Shor Albert TuckerMajor subfields EditConvex programming studies the case when the objective function is convex minimization or concave maximization and the constraint set is convex This can be viewed as a particular case of nonlinear programming or as generalization of linear or convex quadratic programming Linear programming LP a type of convex programming studies the case in which the objective function f is linear and the constraints are specified using only linear equalities and inequalities Such a constraint set is called a polyhedron or a polytope if it is bounded Second order cone programming SOCP is a convex program and includes certain types of quadratic programs Semidefinite programming SDP is a subfield of convex optimization where the underlying variables are semidefinite matrices It is a generalization of linear and convex quadratic programming Conic programming is a general form of convex programming LP SOCP and SDP can all be viewed as conic programs with the appropriate type of cone Geometric programming is a technique whereby objective and inequality constraints expressed as posynomials and equality constraints as monomials can be transformed into a convex program Integer programming studies linear programs in which some or all variables are constrained to take on integer values This is not convex and in general much more difficult than regular linear programming Quadratic programming allows the objective function to have quadratic terms while the feasible set must be specified with linear equalities and inequalities For specific forms of the quadratic term this is a type of convex programming Fractional programming studies optimization of ratios of two nonlinear functions The special class of concave fractional programs can be transformed to a convex optimization problem Nonlinear programming studies the general case in which the objective function or the constraints or both contain nonlinear parts This may or may not be a convex program In general whether the program is convex affects the difficulty of solving it Stochastic programming studies the case in which some of the constraints or parameters depend on random variables Robust optimization is like stochastic programming an attempt to capture uncertainty in the data underlying the optimization problem Robust optimization aims to find solutions that are valid under all possible realizations of the uncertainties defined by an uncertainty set Combinatorial optimization is concerned with problems where the set of feasible solutions is discrete or can be reduced to a discrete one Stochastic optimization is used with random noisy function measurements or random inputs in the search process Infinite dimensional optimization studies the case when the set of feasible solutions is a subset of an infinite dimensional space such as a space of functions Heuristics and metaheuristics make few or no assumptions about the problem being optimized Usually heuristics do not guarantee that any optimal solution need be found On the other hand heuristics are used to find approximate solutions for many complicated optimization problems Constraint satisfaction studies the case in which the objective function f is constant this is used in artificial intelligence particularly in automated reasoning Constraint programming is a programming paradigm wherein relations between variables are stated in the form of constraints Disjunctive programming is used where at least one constraint must be satisfied but not all It is of particular use in scheduling Space mapping is a concept for modeling and optimization of an engineering system to high fidelity fine model accuracy exploiting a suitable physically meaningful coarse or surrogate model In a number of subfields the techniques are designed primarily for optimization in dynamic contexts that is decision making over time Calculus of variations Is concerned with finding the best way to achieve some goal such as finding a surface whose boundary is a specific curve but with the least possible area Optimal control theory is a generalization of the calculus of variations which introduces control policies Dynamic programming is the approach to solve the stochastic optimization problem with stochastic randomness and unknown model parameters It studies the case in which the optimization strategy is based on splitting the problem into smaller subproblems The equation that describes the relationship between these subproblems is called the Bellman equation Mathematical programming with equilibrium constraints is where the constraints include variational inequalities or complementarities Multi objective optimization Edit Main article Multi objective optimization Adding more than one objective to an optimization problem adds complexity For example to optimize a structural design one would desire a design that is both light and rigid When two objectives conflict a trade off must be created There may be one lightest design one stiffest design and an infinite number of designs that are some compromise of weight and rigidity The set of trade off designs that improve upon one criterion at the expense of another is known as the Pareto set The curve created plotting weight against stiffness of the best designs is known as the Pareto frontier A design is judged to be Pareto optimal equivalently Pareto efficient or in the Pareto set if it is not dominated by any other design If it is worse than another design in some respects and no better in any respect then it is dominated and is not Pareto optimal The choice among Pareto optimal solutions to determine the favorite solution is delegated to the decision maker In other words defining the problem as multi objective optimization signals that some information is missing desirable objectives are given but combinations of them are not rated relative to each other In some cases the missing information can be derived by interactive sessions with the decision maker Multi objective optimization problems have been generalized further into vector optimization problems where the partial ordering is no longer given by the Pareto ordering Multi modal or global optimization Edit Optimization problems are often multi modal that is they possess multiple good solutions They could all be globally good same cost function value or there could be a mix of globally good and locally good solutions Obtaining all or at least some of the multiple solutions is the goal of a multi modal optimizer Classical optimization techniques due to their iterative approach do not perform satisfactorily when they are used to obtain multiple solutions since it is not guaranteed that different solutions will be obtained even with different starting points in multiple runs of the algorithm Common approaches to global optimization problems where multiple local extrema may be present include evolutionary algorithms Bayesian optimization and simulated annealing Classification of critical points and extrema EditFeasibility problem Edit The satisfiability problem also called the feasibility problem is just the problem of finding any feasible solution at all without regard to objective value This can be regarded as the special case of mathematical optimization where the objective value is the same for every solution and thus any solution is optimal Many optimization algorithms need to start from a feasible point One way to obtain such a point is to relax the feasibility conditions using a slack variable with enough slack any starting point is feasible Then minimize that slack variable until the slack is null or negative Existence Edit The extreme value theorem of Karl Weierstrass states that a continuous real valued function on a compact set attains its maximum and minimum value More generally a lower semi continuous function on a compact set attains its minimum an upper semi continuous function on a compact set attains its maximum point or view Necessary conditions for optimality Edit One of Fermat s theorems states that optima of unconstrained problems are found at stationary points where the first derivative or the gradient of the objective function is zero see first derivative test More generally they may be found at critical points where the first derivative or gradient of the objective function is zero or is undefined or on the boundary of the choice set An equation or set of equations stating that the first derivative s equal s zero at an interior optimum is called a first order condition or a set of first order conditions Optima of equality constrained problems can be found by the Lagrange multiplier method The optima of problems with equality and or inequality constraints can be found using the Karush Kuhn Tucker conditions Sufficient conditions for optimality Edit While the first derivative test identifies points that might be extrema this test does not distinguish a point that is a minimum from one that is a maximum or one that is neither When the objective function is twice differentiable these cases can be distinguished by checking the second derivative or the matrix of second derivatives called the Hessian matrix in unconstrained problems or the matrix of second derivatives of the objective function and the constraints called the bordered Hessian in constrained problems The conditions that distinguish maxima or minima from other stationary points are called second order conditions see Second derivative test If a candidate solution satisfies the first order conditions then the satisfaction of the second order conditions as well is sufficient to establish at least local optimality Sensitivity and continuity of optima Edit The envelope theorem describes how the value of an optimal solution changes when an underlying parameter changes The process of computing this change is called comparative statics The maximum theorem of Claude Berge 1963 describes the continuity of an optimal solution as a function of underlying parameters Calculus of optimization Edit Main article Karush Kuhn Tucker conditions See also Critical point mathematics Differential calculus Gradient Hessian matrix Positive definite matrix Lipschitz continuity Rademacher s theorem Convex function and Convex analysis For unconstrained problems with twice differentiable functions some critical points can be found by finding the points where the gradient of the objective function is zero that is the stationary points More generally a zero subgradient certifies that a local minimum has been found for minimization problems with convex functions and other locally Lipschitz functions Further critical points can be classified using the definiteness of the Hessian matrix If the Hessian is positive definite at a critical point then the point is a local minimum if the Hessian matrix is negative definite then the point is a local maximum finally if indefinite then the point is some kind of saddle point Constrained problems can often be transformed into unconstrained problems with the help of Lagrange multipliers Lagrangian relaxation can also provide approximate solutions to difficult constrained problems When the objective function is a convex function then any local minimum will also be a global minimum There exist efficient numerical techniques for minimizing convex functions such as interior point methods Global convergence Edit More generally if the objective function is not a quadratic function then many optimization methods use other methods to ensure that some subsequence of iterations converges to an optimal solution The first and still popular method for ensuring convergence relies on line searches which optimize a function along one dimension A second and increasingly popular method for ensuring convergence uses trust regions Both line searches and trust regions are used in modern methods of non differentiable optimization Usually a global optimizer is much slower than advanced local optimizers such as BFGS so often an efficient global optimizer can be constructed by starting the local optimizer from different starting points Computational optimization techniques EditTo solve problems researchers may use algorithms that terminate in a finite number of steps or iterative methods that converge to a solution on some specified class of problems or heuristics that may provide approximate solutions to some problems although their iterates need not converge Optimization algorithms Edit See also List of optimization algorithms Simplex algorithm of George Dantzig designed for linear programming Extensions of the simplex algorithm designed for quadratic programming and for linear fractional programming Variants of the simplex algorithm that are especially suited for network optimization Combinatorial algorithms Quantum optimization algorithmsIterative methods Edit Main article Iterative method The iterative methods used to solve problems of nonlinear programming differ according to whether they evaluate Hessians gradients or only function values While evaluating Hessians H and gradients G improves the rate of convergence for functions for which these quantities exist and vary sufficiently smoothly such evaluations increase the computational complexity or computational cost of each iteration In some cases the computational complexity may be excessively high One major criterion for optimizers is just the number of required function evaluations as this often is already a large computational effort usually much more effort than within the optimizer itself which mainly has to operate over the N variables The derivatives provide detailed information for such optimizers but are even harder to calculate e g approximating the gradient takes at least N 1 function evaluations For approximations of the 2nd derivatives collected in the Hessian matrix the number of function evaluations is in the order of N Newton s method requires the 2nd order derivatives so for each iteration the number of function calls is in the order of N but for a simpler pure gradient optimizer it is only N However gradient optimizers need usually more iterations than Newton s algorithm Which one is best with respect to the number of function calls depends on the problem itself Methods that evaluate Hessians or approximate Hessians using finite differences Newton s method Sequential quadratic programming A Newton based method for small medium scale constrained problems Some versions can handle large dimensional problems Interior point methods This is a large class of methods for constrained optimization some of which use only sub gradient information and others of which require the evaluation of Hessians Methods that evaluate gradients or approximate gradients in some way or even subgradients Coordinate descent methods Algorithms which update a single coordinate in each iteration Conjugate gradient methods Iterative methods for large problems In theory these methods terminate in a finite number of steps with quadratic objective functions but this finite termination is not observed in practice on finite precision computers Gradient descent alternatively steepest descent or steepest ascent A slow method of historical and theoretical interest which has had renewed interest for finding approximate solutions of enormous problems Subgradient methods An iterative method for large locally Lipschitz functions using generalized gradients Following Boris T Polyak subgradient projection methods are similar to conjugate gradient methods Bundle method of descent An iterative method for small medium sized problems with locally Lipschitz functions particularly for convex minimization problems similar to conjugate gradient methods Ellipsoid method An iterative method for small problems with quasiconvex objective functions and of great theoretical interest particularly in establishing the polynomial time complexity of some combinatorial optimization problems It has similarities with Quasi Newton methods Conditional gradient method Frank Wolfe for approximate minimization of specially structured problems with linear constraints especially with traffic networks For general unconstrained problems this method reduces to the gradient method which is regarded as obsolete for almost all problems Quasi Newton methods Iterative methods for medium large problems e g N lt 1000 Simultaneous perturbation stochastic approximation SPSA method for stochastic optimization uses random efficient gradient approximation Methods that evaluate only function values If a problem is continuously differentiable then gradients can be approximated using finite differences in which case a gradient based method can be used Interpolation methods Pattern search methods which have better convergence properties than the Nelder Mead heuristic with simplices which is listed below Mirror descentHeuristics Edit Main article Heuristic algorithm Besides finitely terminating algorithms and convergent iterative methods there are heuristics A heuristic is any algorithm which is not guaranteed mathematically to find the solution but which is nevertheless useful in certain practical situations List of some well known heuristics Differential evolution Dynamic relaxation Evolutionary algorithms Genetic algorithms Hill climbing with random restart Memetic algorithm Nelder Mead simplicial heuristic A popular heuristic for approximate minimization without calling gradients Particle swarm optimization Simulated annealing Stochastic tunneling Tabu searchApplications EditMechanics Edit Problems in rigid body dynamics in particular articulated rigid body dynamics often require mathematical programming techniques since you can view rigid body dynamics as attempting to solve an ordinary differential equation on a constraint manifold 5 the constraints are various nonlinear geometric constraints such as these two points must always coincide this surface must not penetrate any other or this point must always lie somewhere on this curve Also the problem of computing contact forces can be done by solving a linear complementarity problem which can also be viewed as a QP quadratic programming problem Many design problems can also be expressed as optimization programs This application is called design optimization One subset is the engineering optimization and another recent and growing subset of this field is multidisciplinary design optimization which while useful in many problems has in particular been applied to aerospace engineering problems This approach may be applied in cosmology and astrophysics 6 Economics and finance Edit Economics is closely enough linked to optimization of agents that an influential definition relatedly describes economics qua science as the study of human behavior as a relationship between ends and scarce means with alternative uses 7 Modern optimization theory includes traditional optimization theory but also overlaps with game theory and the study of economic equilibria The Journal of Economic Literature codes classify mathematical programming optimization techniques and related topics under JEL C61 C63 In microeconomics the utility maximization problem and its dual problem the expenditure minimization problem are economic optimization problems Insofar as they behave consistently consumers are assumed to maximize their utility while firms are usually assumed to maximize their profit Also agents are often modeled as being risk averse thereby preferring to avoid risk Asset prices are also modeled using optimization theory though the underlying mathematics relies on optimizing stochastic processes rather than on static optimization International trade theory also uses optimization to explain trade patterns between nations The optimization of portfolios is an example of multi objective optimization in economics Since the 1970s economists have modeled dynamic decisions over time using control theory 8 For example dynamic search models are used to study labor market behavior 9 A crucial distinction is between deterministic and stochastic models 10 Macroeconomists build dynamic stochastic general equilibrium DSGE models that describe the dynamics of the whole economy as the result of the interdependent optimizing decisions of workers consumers investors and governments 11 12 Electrical engineering Edit Some common applications of optimization techniques in electrical engineering include active filter design 13 stray field reduction in superconducting magnetic energy storage systems space mapping design of microwave structures 14 handset antennas 15 16 17 electromagnetics based design Electromagnetically validated design optimization of microwave components and antennas has made extensive use of an appropriate physics based or empirical surrogate model and space mapping methodologies since the discovery of space mapping in 1993 18 19 Civil engineering Edit Optimization has been widely used in civil engineering Construction management and transportation engineering are among the main branches of civil engineering that heavily rely on optimization The most common civil engineering problems that are solved by optimization are cut and fill of roads life cycle analysis of structures and infrastructures 20 resource leveling 21 22 water resource allocation traffic management 23 and schedule optimization Operations research Edit Another field that uses optimization techniques extensively is operations research 24 Operations research also uses stochastic modeling and simulation to support improved decision making Increasingly operations research uses stochastic programming to model dynamic decisions that adapt to events such problems can be solved with large scale optimization and stochastic optimization methods Control engineering Edit Mathematical optimization is used in much modern controller design High level controllers such as model predictive control MPC or real time optimization RTO employ mathematical optimization These algorithms run online and repeatedly determine values for decision variables such as choke openings in a process plant by iteratively solving a mathematical optimization problem including constraints and a model of the system to be controlled Geophysics Edit Optimization techniques are regularly used in geophysical parameter estimation problems Given a set of geophysical measurements e g seismic recordings it is common to solve for the physical properties and geometrical shapes of the underlying rocks and fluids The majority of problems in geophysics are nonlinear with both deterministic and stochastic methods being widely used Molecular modeling Edit Main article Molecular modeling Nonlinear optimization methods are widely used in conformational analysis Computational systems biology Edit Main article Computational systems biology Optimization techniques are used in many facets of computational systems biology such as model building optimal experimental design metabolic engineering and synthetic biology 25 Linear programming has been applied to calculate the maximal possible yields of fermentation products 25 and to infer gene regulatory networks from multiple microarray datasets 26 as well as transcriptional regulatory networks from high throughput data 27 Nonlinear programming has been used to analyze energy metabolism 28 and has been applied to metabolic engineering and parameter estimation in biochemical pathways 29 Machine learning Edit Main article Machine learning OptimizationSolvers EditMain article List of optimization softwareSee also EditBrachistochrone Curve fitting Deterministic global optimization Goal programming Important publications in optimization Least squares Mathematical Optimization Society formerly Mathematical Programming Society Mathematical optimization algorithms Mathematical optimization software Process optimization Simulation based optimization Test functions for optimization Variational calculus Vehicle routing problemNotes Edit The Nature of Mathematical Programming Archived 2014 03 05 at the Wayback Machine Mathematical Programming Glossary INFORMS Computing Society Martins Joaquim R R A Ning Andrew 2021 10 01 Engineering Design Optimization Cambridge University Press ISBN 978 1108833417 Du D Z Pardalos P M Wu W 2008 History of Optimization In Floudas C Pardalos P eds Encyclopedia of Optimization Boston Springer pp 1538 1542 W Erwin Diewert 2008 cost functions The New Palgrave Dictionary of Economics 2nd Edition Contents Vereshchagin A F 1989 Modelling and control of motion of manipulation robots Soviet Journal of Computer and Systems Sciences 27 5 29 38 Haggag S Desokey F Ramadan M 2017 A cosmological inflationary model using optimal control Gravitation and Cosmology 23 3 236 239 Bibcode 2017GrCo 23 236H doi 10 1134 S0202289317030069 ISSN 1995 0721 S2CID 125980981 Lionel Robbins 1935 2nd ed An Essay on the Nature and Significance of Economic Science Macmillan p 16 Dorfman Robert 1969 An Economic Interpretation of Optimal Control Theory American Economic Review 59 5 817 831 JSTOR 1810679 Sargent Thomas J 1987 Search Dynamic Macroeconomic Theory Harvard University Press pp 57 91 ISBN 9780674043084 A G Malliaris 2008 stochastic optimal control The New Palgrave Dictionary of Economics 2nd Edition Abstract Archived 2017 10 18 at the Wayback Machine Rotemberg Julio Woodford Michael 1997 An Optimization based Econometric Framework for the Evaluation of Monetary Policy PDF NBER Macroeconomics Annual 12 297 346 doi 10 2307 3585236 JSTOR 3585236 From The New Palgrave Dictionary of Economics 2008 2nd Edition with Abstract links numerical optimization methods in economics by Karl Schmedders convex programming by Lawrence E Blume Arrow Debreu model of general equilibrium by John Geanakoplos De Bishnu Prasad Kar R Mandal D Ghoshal S P 2014 09 27 Optimal selection of components value for analog active filter design using simplex particle swarm optimization International Journal of Machine Learning and Cybernetics 6 4 621 636 doi 10 1007 s13042 014 0299 0 ISSN 1868 8071 S2CID 13071135 Koziel Slawomir Bandler John W January 2008 Space Mapping With Multiple Coarse Models for Optimization of Microwave Components IEEE Microwave and Wireless Components Letters 18 1 1 3 CiteSeerX 10 1 1 147 5407 doi 10 1109 LMWC 2007 911969 S2CID 11086218 Tu Sheng Cheng Qingsha S Zhang Yifan Bandler John W Nikolova Natalia K July 2013 Space Mapping Optimization of Handset Antennas Exploiting Thin Wire Models IEEE Transactions on Antennas and Propagation 61 7 3797 3807 Bibcode 2013ITAP 61 3797T doi 10 1109 TAP 2013 2254695 N Friedrich Space mapping outpaces EM optimization in handset antenna design microwaves amp rf August 30 2013 Cervantes Gonzalez Juan C Rayas Sanchez Jose E Lopez Carlos A Camacho Perez Jose R Brito Brito Zabdiel Chavez Hurtado Jose L February 2016 Space mapping optimization of handset antennas considering EM effects of mobile phone components and human body International Journal of RF and Microwave Computer Aided Engineering 26 2 121 128 doi 10 1002 mmce 20945 S2CID 110195165 Bandler J W Biernacki R M Chen Shao Hua Grobelny P A Hemmers R H 1994 Space mapping technique for electromagnetic optimization IEEE Transactions on Microwave Theory and Techniques 42 12 2536 2544 Bibcode 1994ITMTT 42 2536B doi 10 1109 22 339794 Bandler J W Biernacki R M Shao Hua Chen Hemmers R H Madsen K 1995 Electromagnetic optimization exploiting aggressive space mapping IEEE Transactions on Microwave Theory and Techniques 43 12 2874 2882 Bibcode 1995ITMTT 43 2874B doi 10 1109 22 475649 Piryonesi Sayed Madeh Tavakolan Mehdi 9 January 2017 A mathematical programming model for solving cost safety optimization CSO problems in the maintenance of structures KSCE Journal of Civil Engineering 21 6 2226 2234 doi 10 1007 s12205 017 0531 z S2CID 113616284 Hegazy Tarek June 1999 Optimization of Resource Allocation and Leveling Using Genetic Algorithms Journal of Construction Engineering and Management 125 3 167 175 doi 10 1061 ASCE 0733 9364 1999 125 3 167 Piryonesi S Madeh Nasseri Mehran Ramezani Abdollah 9 July 2018 Piryonesi S M Nasseri M amp Ramezani A 2018 Resource leveling in construction projects with activity splitting and resource constraints a simulated annealing optimization Canadian Journal of Civil Engineering 46 81 86 doi 10 1139 cjce 2017 0670 hdl 1807 93364 S2CID 116480238 Herty M Klar A 2003 01 01 Modeling Simulation and Optimization of Traffic Flow Networks SIAM Journal on Scientific Computing 25 3 1066 1087 Bibcode 2003SJSC 25 1066H doi 10 1137 S106482750241459X ISSN 1064 8275 New force on the political scene the Seophonisten Archived from the original on 18 December 2014 Retrieved 14 September 2013 a b Papoutsakis Eleftherios Terry February 1984 Equations and calculations for fermentations of butyric acid bacteria Biotechnology and Bioengineering 26 2 174 187 doi 10 1002 bit 260260210 ISSN 0006 3592 PMID 18551704 S2CID 25023799 Wang Yong Joshi Trupti Zhang Xiang Sun Xu Dong Chen Luonan 2006 07 24 Inferring gene regulatory networks from multiple microarray datasets Bioinformatics 22 19 2413 2420 doi 10 1093 bioinformatics btl396 ISSN 1460 2059 PMID 16864593 Wang Rui Sheng Wang Yong Zhang Xiang Sun Chen Luonan 2007 09 22 Inferring transcriptional regulatory networks from high throughput data Bioinformatics 23 22 3056 3064 doi 10 1093 bioinformatics btm465 ISSN 1460 2059 PMID 17890736 Vo Thuy D Paul Lee W N Palsson Bernhard O May 2007 Systems analysis of energy metabolism elucidates the affected respiratory chain complex in Leigh s syndrome Molecular Genetics and Metabolism 91 1 15 22 doi 10 1016 j ymgme 2007 01 012 ISSN 1096 7192 PMID 17336115 Mendes P Kell D 1998 Non linear optimization of biochemical pathways applications to metabolic engineering and parameter estimation Bioinformatics 14 10 869 883 doi 10 1093 bioinformatics 14 10 869 ISSN 1367 4803 PMID 9927716 Further reading EditBoyd Stephen P Vandenberghe Lieven 2004 Convex Optimization Cambridge Cambridge University Press ISBN 0 521 83378 7 Gill P E Murray W Wright M H 1982 Practical Optimization London Academic Press ISBN 0 12 283952 8 Lee Jon 2004 A First Course in Combinatorial Optimization Cambridge University Press ISBN 0 521 01012 8 Nocedal Jorge Wright Stephen J 2006 Numerical Optimization 2nd ed Berlin Springer ISBN 0 387 30303 0 External links Edit Wikimedia Commons has media related to Mathematical optimization Decision Tree for Optimization Software Links to optimization source codes Global optimization EE364a Convex Optimization I Course from Stanford University Varoquaux Gael Mathematical Optimization Finding Minima of Functions Retrieved from https en wikipedia org w index php title Mathematical optimization amp oldid 1149143014, wikipedia, wiki, book, books, library,

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