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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Proof required for an alternate method in solving a linear programming problem

Suppose that P and Q are two of the corner points of the feasible region lying completely in the first quadrant. In addition, P is located at South-East of Q*. z = 0 (or more specifically, Ax + By = 0) is a profit function (or any other terms…
Mick
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Is an algorithm to find whether a given Linear Programming problem is degenerate or not?

Is there an algorithm to detect the existence of Degeneracy before solving a given Linear Programming problem by simplex method (search through extreme points)?
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Consider the following LP. Apply surplus variables & initial tableau. Then use revised simplex method to obtain the tableau for basic variables

Consider this LP problem. \begin{array}{cccll} \min & Z= & 8x & +10y+25z & \\ \text{s.t.} & & 2x & \phantom{+10y}+ 2z & \ge 60 \\ & & 2x & +4y+5z & \ge 70 \\ & & &…
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Prove that the following two statemetns are equivalent.

Let be $B\in\mathbb R^{m \times n}$, $C\in\mathbb R^{k \times n}$, $D\in\mathbb R^{l \times n}$, $x\in\mathbb R^{n}$, $y\in\mathbb R^{m}$, $z\in\mathbb R^{k}$ and $u\in\mathbb R^{l}$, then $\exists x: Bx\le0, Bx\ne0, Cx\le0, Dx=0$ $\nexists(y,z,u):…
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What does it mean, geometrically, that a linear program is infeasible?

Suppose I have a linear program (LP) with the constraints $\mathbf{A}\mathbf{x}\leqslant \mathbf{b}$. A feasible solution $\mathbf{x}$ to the LP is a solution that satisfies the constraints $\mathbf{A}\mathbf{x}\leqslant \mathbf{b}$. If there is no…
Ribz
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Use Exact Non-linear formulation or a linear approximation?

I am writing a paper that discusses results to solve stochastic problems with recourse analytically. The problem is nonlinear. I can also write an approximate stochastic linear program to sove the problem. The non-linear formuation is exact, and…
sub
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Linear Optimization/Linear Programming - Vending Machine Problem

I have a question about the formulation of a LP involving fulfilling orders of a vending machine. We have a vending machine which dispenses medicine to its patients. We assume that we have a list of data showing us what each patient is demanding.…
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Why don't we allow a linear programming problem to have strictly '<' or '>' constraints?

I am new to linear programming and I have been asked this question "Why don't we allow a linear programming problem to have strictly '<' or '>' constraints?" But unable to answer it. Kindly provide me an explanation on this.
Arpitgt
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Infeasible solutions in linear programming

Is it possible to determine the cause of an infeasible linear programming model? If so, what's the approach?
Bastian
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Extension of Solutions to Binary Equations

In this post, I asked a question regarding solutions to system of binary equations. The answer that was accepted provided a complete structural solution to the question. I have been working on a derivative of this problem that follows. Given a…
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How to find the highest possible number of quantity in both categories?

This question seemed pretty easy to me, but I have the wrong answer according to my textbook. In a graduating class of 236 students, 142 took algebra and 121 took chemistry. What is the greatest possible number of students that could have taken…
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Linear programming involves products?

I've encountered an unusual constraint in a LP while reading a paper. I would like to know if the problem remains linear despite the inclusion of this constraint: $\sum_{i=1}^{g} \prod_{k=1}^{n}X_{ijk}=1 \hspace{1cm}\forall j=1\cdots m$ where the…
crypto
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maximize linear combination where parameters are non-negative and sum to 1

Here is the problem: $$L = \sum_{i\in [1,n]} a_i x_i \\ s.t. \sum_{i\in [1,n]} x_i = 1, \text{and } x_i >= 0 $$ I think this is a linear programming problem, and I tried to solve it by Lagrange multiplier but no idea at all. However, I know that the…
avocado
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Linear Programming Formulate

A small firm produces three types of wooden lampstands: rounded,angular and rectangular. All types require two hand-crafted processes: cutting and smoothing. Rounded lampstands require 1 hour of cutting and 3 hours of smoothing whereas Angular…
John
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Linear programming.

In the given diagram the co-ordinates of B and C are $(-2,-1)$ and $(-2,8)$ respectively. The shaded region inside the $\triangle ABC$ represented by three inequalities. One of these is $x + y <=6$. Write down the co-ordinates of A and other two…