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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Uniqueness of Solution in infinite linear programming

I would like to ask about a sufficient condition under which a solution for an infinite linear programming is unique. In standard finite dimensional linear programmings, like $\min_x p\cdot x$ subject to $Ax\ge b$, it is known by Mangasarian (1978)…
tarou2
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Setting up a linear programming word problem

Problem: A metalworking shop needs to cut at least 32 large disks and 219 small ones. There are three cutting patterns for the standard size metal rectangle. One cutting pattern produces two large disks with 14% waste. A second cutting pattern…
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Conditions for a LP to be integral

What are the conditions to be met by a LP that allows to infer that its optimum solution will be integral? Is total unimodularity a necessary and/or sufficient condition? What if all variables are binary?
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LP Word Problem Construction

I am having difficulty constructing the constraints on a word problem as follows: The Brite-lite Company receives an order for 78 floor lamps, 198 dresser lamps, and 214 table lamps from condoski Corp. Brite-Lit ships orders in two types of…
Vivid
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Linear Programming:What combination of two loams to minimize cost

I am fairly new to linear programming so simplification would be helpful.Came across a certain question and unfortunately no answer for it at the back of the book. The question is adopted from a book called An Introduction To Linear Programming And…
Manny265
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LP program: does the decision variable coefficients affect the problem?

I just started reading up on linear programming by myself, and am a bit confused by the decision variable coefficients $c_j$, in the objective function $ \sum_j c_jx_j$. Do they matter? I mean, if I replace $4x + 2y$ with $2x + y$, or with $8x +…
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extreme points and representing

$$X=\{(x_1,x_2)^T : x_1-x_2\leq3, 2x_1+x_2\leq 4, x_1\geq -3\}$$ Find all extreme points of $X$, and represent $x^*= {0\choose1}$ as a convex combination of those extreme points. I sketched it out with $x_2$ being the vertical axis and $x_1$ being…
snowman
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Calculating the distribution between a range without an MILP solver?

I am currently using a MILP calculation and I was wondering if anyone can recommend a more mathematically simplistic method of calculating this distribution and arriving at a similar result? Qty - 15 shares Range - 10-20 Target average price - <=…
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Let $P$ be a minimization primal problem $\min c^T x$. Does $P$ and its dual $P^*$ always have the same number of optimal solutions?

Let $P$ be a minimization primal problem $\min c^T x$ and let $P^*$ be its dual. I've been wondering about the following: Suppose $P$ has exactly $n$ optimal solutions. I know that $P^*$ also has an optimal solution $\bar u$ with the same objective…
Shuzheng
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Linear programming problem-optimal solution

I'm having the following linear programming problem: $$\begin{align} \max \quad & 2x_{1}+6x_{2}+3x_{3}, & \\ \text{s.t.} \quad & -3x_{2}+a x_{3} \geq2, \\ & x_{1}+5x_{2}+2x_{3} =2, \\ & x_{1},x_{2},x_{3} \geq 0 \end{align}$$ for which value of $a$…
Mary Star
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Solve this linear program graphically

Solve the following linear program graphically: $\begin{array}{ll} \underset{x_1, x_2}{\text{maximize}} & 25 x_1 + 20 x_2\\ \text{subject to} & 3x_1 + 6x_2 \leq 50 \\ & x_1 + 2x_2 \leq 10 \\ & x_1 \geq 0, x_2 \geq 0 \end{array}$
Avijat
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Removing the Worst Swimmer Using Linear programming

Given a table of personal best records of 5 people in 4 different swimming styles (freestyle stroke, backstroke, breaststroke, butterfly stroke) how can I choose 4 out of 5 said swimmers for an upcoming competition (Using Linear Programming). There…
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Unboundedness in linear programming

Let $K = \{ x : Ax \le b, x \ge 0 \}$, $b \ge 0$. If there are solutions $x \ge 0$ different from zero of $A x \le 0$, show that $K$ is unbounded.(A is mxn, x is 1xn b is 1xm matrix.)
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How to design feasible region bounded question?

A company has budgeted 10 million dollars in capital expenditure over the next five year to acquire new fixed assets such as property, plants and equipment. How can I solve the problem that the feasible region is bounded and there is precisely one…
user8314628
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Big M method in LPP

In big M method the artificial variable is given cost as -M in case of maximisation problem. But what is the reason for taking "-M" ( M being a very large value)
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