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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solving minimum linear programming with simplex method

I want to solve a minimizing linear programming problem with simplex method. $$min \quad 2x_1+3x_2+x_3 \\ \text{subject to: }x_1+4x_2 \le 3 \\ x_2+4x_3 \le 2 \\ x_1+2x_2+3x_3=5 \\ x_2+x_3=1 $$ In order to solve this problem with simplex method it…
Masoud
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Can standard Linear Programming algorithms return all valid solutions without losing their efficiency?

I have a (generalized) Linear Programming problem to solve. I anticipate exactly two equally valid optimizations of my objective function. I would be happy if I could receive both these points; it wouldn't be hard to figure out which one I really…
GMB
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Showing values of the variables to be indeterminate

I am new to linear programming, so please don't blast me if this question is too trivial for you. I was trying to solve the following equation, $\max p = 0.00085671xz + 0.00288211xy + 0.00115083yz + 0.00174047xz + 0.00415733zy + 0.00070583zz $…
arman
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A small computer manufacturing company

any body can help me with this ? A small computer manufacturing company forecasts the demand over the next $n$ months to be $d_i$ $i = 1, 2.... n.$ In any month it can produce $r$ units, using regular production, at a cost of $b$ dollars per unit.…
spd
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Maximize Fractional Function on Hypercube

Let $a_{i,j}$ and $b_{i,j}$ be real numbers for $i,j\in\{1,\ldots,m\}$. Let $z_k\in\{0,1\}$ for $k=1,\ldots,m$. Is there a common method of maximizing, $f(z_1,\ldots,z_m)=\displaystyle\frac{\sum_{(i,j)} a_{i,j}z_iz_j}{\sum_{(i,j)} b_{i,j}z_iz_j}$ A…
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Linear programming graphically

A small firm produces two types of wooden lampstands: rounded and angular. Both types require two hand-crafted processes: cutting and smoothing. Rounded lampstands require 1 hour of cutting and 3 hours of smoothing whereas angular lampstands require…
John
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Linear Programming Sum

The Handy-Dandy Company makes three types of kitchen appliances ($A$, $B$ and $C$). To make each of these appliance types, just two inputs are required - labour and materials. Each unit of $A$ made requires $7$ hours of labour and $4$ kg of…
Tom
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Stuck on setting up system of equations problem: firm with four goods that use 3 inputs

I'm having trouble setting up this problem. A firm produces 4 kinds of goods: G1, G2,G3,G4. Each good requires three kinds of input: Labor, Row Materials, Capital (quantity if each input needed for each good is noted in the table…
John
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Linear programming without use Gauss-Jordan row operations

I want some help for the following LP: $$\begin{align} \mbox{maximize} \quad& 24 x_1 + 22 x_2 + 45 x_3 \\ \mbox{subject to} \quad& 2x_1+x_2+3x_3 \leq 42 \\ & 2x_1 + x_2 + 2x_3 \leq 40 \\ & x_1 + \tfrac{1}{2}x_2 + x_3 \leq 45 \\ & x_1, x_2, x_3, x_4…
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Production Scheduling - Linear Programming - College Algebra

It's me. I got an answer for the following question but it just looks wrong lol. It's a decimal. In a factory, machine 1 produces 8-inch (in.) pliers at the rate of 60 units per hour (hr) and 6-in. pliers at the rate of 70 units/hr. Machine 2…
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Convert this problem into linear programming format

This problem is from the book Luenberger "Linear and Non Linear Optimization". I am facing difficulty with this problem. I am trying to follow this logic - Let $t = \max (c_1^Tx+d_1,....,c_p^Tx+d_p)$. Then as $t$ is the maximum value could I…
roni
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GLPK/Linear Programming - if conditions

Imagine that I have two variables fw (>= 0) and a (binary) and my objective function is to minimize: fw. In the constraints part, I want to ensure (among other things that are not important here) that if fw > 0, then a == 1. To ensure this, I used…
Conhada
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AMPL - Step by Step mode

Is there a way to solve a problem using AMPL in a step by step(or a verbose, or a debug) mode? Preferably showing all basis exchanges? The manuals of AMPL make reference to script development, but i didn't found anything about basis exchanges on…
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ILP Problem to minimize two functions one after the other

I am working with a ILP problem. In the problem I would like to minimize f(x0+..+xn) and then if multiple optimal solutions exist, minimize g(x0+..+xn) from the subset of those optimal solutions. I am using SYMPHONY to minimize the first function.…
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How many tight constraints does a linear program have?

I have the following constraints of a linear program: $$\sum_{j=1}^{m}x_{ij}=1,\quad\quad1\le i\le n,$$ $$\sum_{i=1}^{n}p_i^k x_{ij}=1,\quad\quad1\le j\le m,\;1\le k\le d,$$ $$x_{ij}\ge 0,\quad\quad1\le i\le n,\;1\le j\le m,$$ The paper I am reading…
drzbir
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