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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real estate developper problem

A real estate developer is planning to build an office complex. Currently, there are three office sizes under consideration: small, medium, and large. Small offices can be rented for $600 $ per month medium offices can be rented for $750 $ per…
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How can I achieve "multi-step" linear programming modelling?

I will try my best to concisely explain my query, but may struggle with terminology and core mathematical logic as I do not come from a formal mathematics background. I have a rudimentary knowledge of linear programming, specifically from its…
user1299028
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Correspondance between two versions of the fundamental theorem of LP

In linear programming I ve seen two versions of the fundamental theorem, and I wonder whether there is a correspondance between them, so that given one version you don't have to prove the other one. The two versions I am talking about can be found…
asdf
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why the optimized point always appear in the interception in LP problem

As the topics, why the optimized point always appear in the interception in LP problem? I think there should be a proof but i am not sure about it.
Mathematics
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The dual of the primal problem

Consider the primal linear programming problem Maximize z =c(transpose) x Subject to Ax<=b X is unrestricted .Then its dual problem given by Minimize ź=b(transpose) w Subject to A(transpose) w =c W>=0 I can't complete the proof proof: Because…
Tasneem
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Relating a binary and an integer variable

Given a binary variable $x$ and an integer variable $y=1,\dotsc,10$. I would like to express that $x=1$ if $y=5, x=0$ otherwise. Is this possible using purely linear constraints? What I'm looking for is the following. Given for instance 2 integer…
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Proof for Linear Programming relating to existence of optimal solution when $A$ has a least one positive entry in each column

I am doing some practice problems and am unsure how to proceed with the following proof: Let $A$ be an $m \times n$ matrix with $A \geq 0$ and each column of $A$ has a non-zero positive entry. Let $b \geq 0$. Then show that the LP $$ \max…
PutsandCalls
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What to do when ratio test gives same result for two different variables? (in Linear Programming)

In simplex algorithm, I applied the ratio test to find the leaving variable but it gave the same result for two variables. Should I choose one of them and calculate the objective function or calculate for both of them, then take the better one?
Sena
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Minimisation using Simplex Tableau

I know there are a number of ways to use a simplex tableau in linear programming to find the minimum value for an equation given constraints, including transposing the simplex tableau etc. etc. However, my teacher specifically mentioned that he…
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Solving an LP with equalities by simplex method

I have the following main program to be solved by simplex method. $$Min \quad P=0.2x_1 + 0.5x_2 + 0.6x_3 + 0.1x_4 + 0.2x_5 + 0.3x_6 \\ \text{subject to: } 0.2x_1 + 0.3x_2 + 0.25x_3 \le 0.8 \\ \quad\quad\quad\quad 0.1x_4 + 0.4x_5 + 0.2x_6 \le 0.8…
Masoud
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Maximizing linear equation with integer

If I have a linear equation like $$ c_1x_1 + c_2x_2 + ... + c_nx_n = m \leq M $$ with the constraint $x_i \in \mathbb{N}$ for $0 \le i \le n$, where $M$ and the $c_i$ are constants, and where the $c_i$ are rational, how do I maximize $m$? A…
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Sensitivity Analysis: Which resource should I buy more?

Let an LP of the form: $\max \ 2x_1+2x_2+x_3$ $s.t. \ x_1+2x_2+x_3 \leq 4 =b_1$ $\ \ \ \ \ \ \ \ 2x_1+x_2+x_3\leq3 =b_2$ $\ \ \ \ \ \ \ \ x_1,x_2\geq0$ And let the final tableau be: being $x_4$ and $x_5$ the slack variables. Question: Which action…
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Showing a linear programming property

Let a linear programming (LP) in the form: $\max \ cx$ $s.t. \ Ax\leq b,$ $\ \ \ \ \ \ \ \ x\geq0$ If this program has an optimal finite solution, then if I exchange $b$ to $\bar{b}$, show that the new LP either has an finite optimal solution or is…
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Is it possible to have more than one basic variables in the same equation for simplex method?

I solve this linear programing problem. But I realized there are more than one basic variable (a variable appearing in only one equation) are present in the same equation. Is it possible to happen or I am making some mistake? There are a lot of…
Masoud
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Can I minimize this with Simplex Method?

I have been working on a problem for a couple months now and I figured I might be able to find the answer if I could minimize the set of players preferences. I am trying to minimize a space where there is $n$ players with $m$ policies and a discrete…