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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Linear optimization, homework problem.

Please help with the following problem: Given a $m \times n$ matrix $A$, $m$-vectors $b$ and $y$, and $n$-vectors $c$ and $x$. Write the dual $LP$ problems $P$ and $P^d$ in the standard form. Whether $x$ (respectively, $y$) is a feasible vector…
Daniel
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Linear program for way optimization with unusual constraints

I've just finished the lecture "Introduction to Optimization", so I know something about linear programming, and came across the following game on lumosity.com: The goal of the game is to pick up all the animals and return them to their houses, by…
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Is Linear Programming a Combinatorial optimization method?

I want to know LP can be considered as a Discrete optimization or continuous. The solutions can be fractions so it should be continuous. Please suggest. thanks
user55531
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Dropping Upper Bounds in a Linear Program

Can anyone explain why usually, in a Linear Program, the upperbound constraints are "redundant" and then they can be dropped? For example, consider: http://en.wikipedia.org/wiki/Set_cover_problem#Integer_linear_program_formulation once I take the LP…
Johan
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Modeling with Linear Programming

Here is the scenario; Let's say that a wholesaler have a storage with the capacity of $75,000$ $m^3$. The stock of corn at the beginning of the year is $15.000$ $m^3$ and the working capital is $ 25,000$ USD. The regulation says that they cannot…
FarahFai
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How to find a polynomial of order $4$ which minimizes a given condition

How to find a polynomial $P(x)$ of order $4$ such that $\max\{\vert\ln(n)-P(n)\vert : 1\leq n \leq12\}$ is as small as possible? I guessed the solution with linear programming, but I don't know how to formulate the equations.
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Converting a Linear Program to Canonical Form

A linear program is said to be in canonical form if it has the following format: Maximize $c^Tx$ subject to $Ax ≤ b$, $x ≥ 0$ where $c$ and $x$ are n-dimensional real vectors, $A$ is an $m × n$ matrix with real entries, and $b$ is an m-dimensional…
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Formula for rate that changes when negative

Is it possible to reduce this code to a single formula, rather than check if x is negative? if (x < 0) value = (x + length) * .5; else value = x + (length * .5); essentially, it's the same formula, but obvious the parenthesis change…
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Dual LP from Primal LP, how?

$$\min x +y + z$$ so that $$ x + y =2$$ and $$y + z = 3$$ where, $x,y,z >0$. How to create the dual? [Something like this?] $$ \max 2s + 3t$$ so that $$ ...+... =1$$ and $$ ...+...=1$$
hhh
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Use duality to find a strong alternative

Find a necessary and sufficient condition for the linear equation Ax = b to have no solution. (hint: Use duality to find a strong alternative to Ax = b).
GBa
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Affine and Linear programming

Can someone give a simple explanation as to why the feasible region of a set of linear program/equations is affine?
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How to choose $u_i$'s for Chvatal-Gomory cutting plane?

Trying to understand the example of Chvatal-Gomory cutting planes (Lee p. 153), they say: $\max 2x_1 + x_2 $ subject to: $7x_1 + x_2 \leq 28$ $-x_1 +3x_2 \leq 7$ $-8x_1 -9x_2 \leq -32 $ $x_1, x_2 \geq 0$ $x_1, x_2 \in…
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Simplex method : Improving a basic feasible solution by Bazaraa

My question is about improving a basic feasible solution according to Bazaraa's explanation (Linear Programming and Network Flows ed II p94) Improving a basic feasible solution $$z_{0}=c_{B}B^{-1}b$$ $$x_{B}=B^{-1}b-B^{-1}Nx_{N}=B^{-1}b-\sum_{j…
com
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Linear Programming - Simplex Method

Let, $\begin{array}{lcl}Min: z =10x_{1}+5x_{2} \\ \\ 20x_{1}+50x_{2} \geq 200 \\ 50x_{1}+10x_{2} \geq 150 \\30x_{1}+30x_{2} \geq 210 \\x_{1},x_{2} \geq 0\end{array}$ a linear programming problem. In standart form one have, $\begin{array}{lcl}Min:…
user24047
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Linear program that is taking a maximum over $n$ linear programs?

Suppose I have feasible linear programming problems $P_1, \dots, P_n$. Say $f$ assigns a feasible linear program its optimum value. How can I find a linear program $P'$, such that $f(P') = max(f(P_1), \dots, f(P_n))$? Preferably $P'$ is of size…