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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optimal basis and optimal solution

Determine which of the following is true: a) Consider a maximization LP in SEF. Suppose $x$ is a basic feasible solution for which all nonbasic variables have strictly negative reduced costs. Then the LP has only one optimal basis. b) Consider a…
Idonknow
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Membership problem for convex cones

Does anyone have a reference for the most efficient or some simple reasonably efficient algorithm for the membership problem for convex cones: Given a finite set of vectors $v_1, ..., v_n$ and a vector $v$, how do you determine whether $v=p_1…
Jon Tyson
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Determining existence of a solution for a system of linear inequalities

I have a set of vectors $\mathbf{v}_1,\mathbf{v}_2,...,\mathbf{v}_m\in\mathbb{R}^n$ and I want to know if there exists a nonzero vector $\mathbf{x}$ such that $\mathbf{x}\cdot\mathbf{v}_i\le0$ for any $i$. This is the same as saying the equation…
Kajelad
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Balancing recipe's ingredients through a system of linear equations: is it the right approach?

I have 4 ingredients that I want to combine to prepare a drink: | amount | pro | carbs | fats | ------------------------------------------------ [m]ilk | 100ml | 3.5 | 5.3 | 0.1 | [o]ats | 100g | 11 | 62 …
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Simplex: outgoing variable cannot re-enter the basis next iteration

How can I prove that in the simplex method, a variable that has just left the basis cannot re-enter the basis on the very next iteration? The pivoting rule is Dantzig's.
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What to do about equality constraints in the Simplex Tableau method

The question I've got is: Maximise $$2x-y+3z$$ subject to $$2y+z \leq 2$$ $$x+y+z=4$$ $$x-2y+z \geq 3$$ $$x,y,z \geq 0$$ Using the Simplex Tableau method. I know that for $\leq$ constraints you need slack variables, for $\geq$ you need slack and…
Nate
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On the Proof of Fundamental Theorem of Linear Programming.

Having read the link: Why maximum/minimum of linear programming occurs at a vertex? I understand why the optimal solution of any linear programming problem must be on the corner or lies on a face of a convex polygon. But my question is about a proof…
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Is a System of Linear Equations the Right Way to Solve This Optimization Problem?

This is kind of a high-level question, in that I'm not sure which mathematical approach might be best for solving my problem. I'm trying to automate a painful, error prone, and time consuming process that we do every year. Our camp gets requests…
iopener
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How to minimize $|x_1| + |x_2|$ via linear programming?

Given $a_{ij}, b_j \in \Bbb R$, consider the following optimization problem: $$\begin{array}{ll} \underset{x_1, x_2 \in \Bbb R}{\text{minimize}} & |x_1| + |x_2|\\ \text{subject to} & a_{11}x_1 + a_{12}x_2 = b_1\\ & a_{21}x_1 + a_{22}x_2 =…
meysam
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Help with formulating a linear programming problem

I have the following linear programming problem I would like to be verified: I have sketched the problem in the following picture: Here is my attempted solution: I figured that I have ten variables (corresponding to the colored lines, between…
jjepsuomi
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Does a linear program always attains its infimum?

Consider the following (Lp). $$ \min \;\; \mathbf{c} \cdot \mathbf{x}\\ \text{s.t. } A\mathbf{x} \geq \mathbf{b} \\ \mathbf{x} \geq \mathbf{0} \\ $$ If $S$ is the feasable set of (Lp), Prove that the following definitions are equivalent. (Lp)…
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Confused about linear programming exercise solution in my textbook

please see this simple linear programming exercise and its solution from my textbook. The task is to convert the prose and matrix to a formal linear programming problem. My answer matched theirs except I got different constraints: $2.5x_A + 3x_B +…
Danny King
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Simplified nurse scheduling problem

I'm currently handling a project with a problem that is very similar to nurse scheduling problem in many respects. It is a part time workforce scheduling system whereby we need to determine which staff is most suitable to work on that a particular…
James
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Linearizing min function Problem

How can I linearize $\min(x_1,x_2,x_3)$ in a maximization linear programming problem? Please help me. I've tried many things but I didn't solve.. My LP equations are as follows: Objective function is: maximize…
John
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Understanding complementary slackness

I've chosen a simple example to help me understand duality and complementary slackness. Suppose we have linear program: $$Maximize\quad 5x_1+x_2\quad s.t$$ $$2x_1+x_2 \le 6$$ $$x_1+x_2 \le 4$$ $$2x_1+10x_2 \le 20$$ $$x_1,x_2 \ge 0$$ $$Solution \quad…
stackdsewew
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