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 calculate incidence matrix

I have the following linear program MIN Z = 8x1 + 8x2 + 3x3 + 6x4 + 3x5 + 5x6 + 2x7 + x8 + 4x9 subject to x1 + x2 = 50 -x1 + x3 + x4 + x6 = 0 -x2 - x3 + x7 - x8 + x9 = 0 -x4 + x5 - x7 = -20 -x5 - x6 + x7 + x8 - x9 = -30 x1 <= 12 x2 <= 5 x5 <= 5 x6…
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Construct a Linear Program

I am learning a little bit of Linear Programming and came across this question which I am unable to solve or even begin solving. The question is: Construct an LP with a feasible region containing four corner points at which the objective function…
MNS
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Linear Programming question

I am kind of lost on this problem and would like it if I can get help on this. Matching Pennies. In this simple two player game, the players (call them R and C) each choose an outcome, heads or tails. If both outcomes are equal, C gives a dollar to…
Rheem
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How to find the optimal replenishment quantity and replenishment frequency given a weekly demand?

I'm helping a wholesaler in perishable products that sales 1200 units a week of a product buyed $30€$ by unit. The order placement cost is $40€$ and the possession cost is $25\%$ a year. We will take, for computations, a stable demand distributed on…
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Show that x is primal feasible

I have one exercise asking me to show that $x*=(3/2,1)$ is primal feasible for the linear programming problem: $$max 3x_1 +2x_2$$ $$2x_1+x_2 \leq 4$$ $$2x_1+3x_2 \leq 6$$ I can see that it fulfill the constraints. But is there any other method to…
MZ97
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Linear programming sensitivity analysis

As I am begineer I want to know if we add new constraint to a lpp then what will change is this *Feasible region or feasible solution *Optimal solution *Both
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Prove that adding a constant to a min-cost assignment problem will not change optimal matching?

Given an assignment problem $\min \sum_{i=1}^{n} \sum_{j=1}^{n} C_{ij} X_{ij}$ subject to $X^t e =e, Xe=e, 0 \leq X \leq 1$ where $e=(1,1,1....1)^t$ I want to prove that if an add an arbitrary $\alpha$ to all elements of matrix C (i.e: replace C by…
Nikitau
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Identifying if an LP is unsolvable or solvable and finding lower bound without Simplex?

I have no idea how to solve the following problem without using Simplex. Below is the LP $\min -47x_1 + 13x_2 + 22x_3 $ subject to $-4x_1 + x_2 - 17x_3 \geq 2$ $-x_1 + x_2 + 39x_3 \geq 1$ $x_1, x_2, x_3 >0$ I have the dual written down as: $\max…
Nikitau
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Showing that a Linear Program has an optimal solution given a condition

I was asked the following question on my linear programming midterm: Consider the following linear program: $$ \text{max } c^{T}x \\ \text{s.t. } Ax \leq b $$ where A is a square $ n \times n $ matrix of full rank. Show that this linear program has…
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Non-graphical method of solving linear programming

$\max x+y$ s.t. $2x+y\le14\\-x+2y\le8\\2x-y\le10\\x\ge0\\y\ge0$ Is there a non graphical way to solve this quickly? Drawing the graph etc can be pretty time consuming in competitive exams! Thanks in advance for any help.
user405925
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Standard form Linear Program

How do i convert this LP $$\text{maximize }x_4$$ $$\text{subject to }\epsilon\leq x_1\leq 1\\\epsilon{x_{j-1}}\leq x_j\leq 1-\epsilon{x_{j-1}}, \quad j=2,...,4 $$ to the standard form $$\text{minimize } c^Tx\\\text{subject to Ax=b}\\x\geq 0$$
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Linear Optimization: Possibilities

To product a product $3$ square plates $A$ with measures $300\times 500$mm and $2$ square plates $B$ with measures $400\times 600$mm are needed. These plates must be cut out by two different workpieces with measres $1000\times 1000$mm (Type I) and…
Mary Star
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How to solve linear programming problems

I'm studying computer programming. Our lecturer in one of the courses gave us the following assignment and told us to learn the material needed to solve it. I'm not a mathematician and would like to minimize effort. How can I solve this problem? Or,…
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minimise $x - 2y$ subject to $x+3y\geq 3$ , $3x + y\geq 3$ and $x + y \leq 3$

Consider the following linear programme: minimise $x - 2y$ subject to $x+3y\geq 3$ , $3x + y\geq 3$ and $x + y \leq 3$ I solved this question graphically and the answer is (0,3). But is there a way to solve it with equations and be absolutely…
user405925
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Linear Programming Constraint

I have a question about one of the constraints in an LP from my homework. A company produces two products, A and B. The sales volume for A is at least 80% of the total sales of both A and B. However, the company cannot sell more than 100 units of…
jbrow35
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