Questions tagged [linear-programming]

Questions on linear programming, the optimization of a linear function subject to linear constraints.

A linear programming problem may be defined as the problem of maximizing or minimizing a linear function subject to linear constraints. The constraints may be equalities or inequalities.

Linear programs are problems that can be expressed in canonical form as \begin{align}\max\quad&c^\top x\\\text{s.t.}\quad& Ax\le b\\\quad& x\ge 0\end{align} where $x$ represents the vector of variables (to be determined), $c$ and $b$ are vectors of (known) coefficients, $A$ is a (known) matrix of coefficients, and ${\displaystyle (\cdot )^{\top}}$ is the matrix transpose.

The expression to be maximized or minimized is called the objective function ($c^{\top}x$ in this case).

The inequalities $Ax \le b$ and $x \ge 0$ are the constraints which specify a convex polytope over which the objective function is to be optimized. The inequality $x \ge 0$ is called non-negativity constraints and are often found in linear programming problems. The other inequality $Ax \le b$ is called the main constraints.

Applications:

Linear programming can be applied to various fields of study. It is widely used in mathematics, and to a lesser extent in business, economics, and for some engineering problems. Industries that use linear programming models include transportation, energy, telecommunications, and manufacturing. It has proven useful in modeling diverse types of problems in planning, routing, scheduling, assignment, and design.

References:

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How to show, that auxiliary problem of linear program always has optimal solution by using fundamental theroem of LP and by formulation of aux.prog?.

I have an interesting question which I need to solve. When we are given linear programing problem and we want to use Simplex method to find the basic feasible and optimal solution of the problem, we need to find some basis, so that we can find basic…
Zam
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Obtaining points of a disconnected set, where every component has at least one such point.

In 14 dimensional euclidean space, I have 30 linear constraints $c_1$, $\cdots$, $c_{30}$ one of which is, for example, either an equation like $$x_1+x_3-x_5+x_{10}=5$$ or an inequality like $$x_1+4x_3-x_5+3x_{10}\ge10.$$ Intersecting all the…
govindah
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How to quickly verify whether a point is an optimal solution of a Linear Programming?

Let $w$ be a given feasible solution to the standard LP: $\min\{c^T x:Ax=b,x\geq 0\}$; Then how can I verify whether $w$ is an optimal solution without solving the LP at all? I know $w$ is optimal if and only if there exists a multiplier $\lambda$…
Yunfei
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Calculation of volume and centre of mass of an arbitrary polyhedron

Hi I am developing a thesis that will calculate the volume and center of mass of an arbitrary block of rock. 1- The calculation starts with triple volume integrals. The formulas are transformed to line integrals using the divergence theorem and …
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MILP problem with time dimensionality and notice period penalty

I am trying to formulate the followng MILP problem (using pyomo with GLPK) but I just can't figure out how to solve it: A company produces one product with different robots. The demand is known. The robots (based on their size) can produce different…
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Bilevel optimization with linear objectives and constraints

I'm looking at the following bilevel optimization problem, where $x \in R^n$ denotes the upper-level variables and $y \in \mathbb{R}^m$ denotes the lower-level variables. The vectors $a,b,c$ and $d$ are strictly positive integral vectors of…
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Techniques to optimize model to present the reason of infeasibility

I want to understand what are the techniques one can explore to debug linear programming related optimization problem which is turning out to be infeasible. It turns out infeasible saying so and so equations lead to infeasibility but the problem is…
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First index pivot rule in LPSolve

I am working on a paper on how pivot rule selection influences the time needed for LPSolve to solve a problem. I have decided to write some teory about different algorithms, but i can't find anything about the "First index" algorithm. Anybody know…
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A linear programming problem

Please guide me on the following question. Consider the LP problem maximize $x_1+x_2$ subject to $x_1-2x_2\le10$ $x_2-2x_1\le10$ $x_1,x_2\ge0$ Which of the following is true? $1.$ The LP problem admits an optimal solution. $2.$ The LP problem is…
aarbee
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Is Converting to Standard Form Necessary to Check if a Proposed Solution is a Basis in Linear Programming?

If I have a Lp problem should I make it to standard form and then calculate number of 0s in the proposed solution and compare it to : number of equation - number of variables; And that's for checking wether the solution is a basis(BFS) or not. What…
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Starting simplex tableau with initial feasible solution

I have the following LP Solve the following problem by the simplex tableau method starting with the basic feasible solution corresponding to the vertex (x1, x2) = (4, 0). $$ \text{maximize }z = -x_1 + 2x_ 2 \\ \text{subject to: } \\ 3x_1 + 4x_2 =…
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Programación Lineal (PL)

quería ver si me pueden ayudar en plantear el modelo de Programación Lineal para este problema. Sunco Oil tiene tres procesos distintos que se pueden aplicar para elaborar varios tipos de gasolina. En cada proceso requiere mezclar crudos en el…
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Linear programming: what does the "test ratio" measure?

When reducing rows in linear programming you pick the one with the lowest test ratio in a certain column, why is that? What does the test ratio mean?
Mike Flynn
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Using the method of feasible regions, solve the linear program

Minimise $\;z=2a+b\;$ subject to $a\leqslant10$ $2a+5b\leqslant60$ $a+b\leqslant18$ $3a+b\leqslant44$ $a\geqslant0$, $\;\;b\geqslant0$ Usually I would plug the extreme points of the feasible region into the objective function but, for this question,…
TM1
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In a linear programming problem, how to define an optimzation function so that solution is equally distributed between the variables.

In a linear programming problem, how to define an optimzation function so that solution is equally distributed between the variables. For example, x + y = 10, I want an optimization function to make sure that x and y are close, here it will be 5,…