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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Is leq sufficient for the existence of a slack variable based bfs in a simplex?

I'm attempting to write a MPS to custom format converter for a generalized simplex algorithm and I am running into a couple of difficulties. According to this tutorial on the Big-M method for finding a basic feasible solution the following is…
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Is it possible to get the dual solution "quickly" once the optimal primal solution is found?

With the primal objective value, I know the dual objective value. I also know the right hand sides of the original program. However, I don't know the values of the dual variables at the optimal point. Is there an easy way to determine those values…
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A question about $n\times n$ matrix

Possible Duplicate: For every matrix $A\in M_{2}( \mathbb{C}) $ there's $X\in M_{2}( \mathbb{C})$ such that $X^2=A$? Square root of a matrix Let $A$ be $n\times n$ matrix on $\mathbb C $. Can I find $B$ such that $B^2=A$? If I can , how do I…
Leitingok
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How to convert a linear optimization problem into a normal form?

The following linear optimization problem is given: $$ \begin{eqnarray} x_1 + 2x_2 -7x_3 \leq 1\\ |3x_1-5x_2-20| \leq 4 \\ x \geq 0 \\ 6x_1+5x_2-3x_3 \rightarrow min \end{eqnarray} $$ And it is my task to convert it into the normal form. The script…
Drudge
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Solve linear algebra equations

I have following question that I kindly need assistance: 2 Products; $x$ and $y$ For every $x$ units sold profit$= 20$ For every $y$ units sold profit$= 50$ Therefore profit function$= (20*x) + (50* y)$ $2$ machines; $1$ and $2$ Machine $1= 100$…
Maurice
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Linear program with bounded feasiblity set

Hey guys I've been stuck on this problem and was wondering if anyone could help. Consider a linear programming problem in standard form with a bounded feasible set. Furthermore, suppose that we know the value of a scalar U such that any feasible…
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Finite Math Word Problem

I have been having trouble with this word problem for a while. A bicycle manufacturer builds one-, three-, and ten-speed models. The bicycles need both aluminum and steel. The company has available 50,075 units of steel and 62,160 units of…
Aszula
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Linear programming formulation of if-then constraint

Consider an LP for which you want to add the restriction that Only if $x_1\geq 3$ then $x_2$ and $x_3$ are allowed to be larger than $0$; otherwise $x_2$ and $x_3$ are $0$. Demonstrate how to formulate this.
Daan
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Linear Programming Problem about optimal solution

Let $X_1$ and $X_2$ are the optimum solutions of LPP, then (a) $X = λX_1+(1- λ)X_2$, $λ \in \Bbb R$ is also an optimal solution (b) $X = λX_1+(1-λ)X_2$, $0 \leq λ \leq 1$ gives an optimal solution (c) $X = λX_1+(1+λ)X_2$, $0 \leq λ \leq 1$ gives an…
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Linear programming: inequality constraints, constrain domain of weights, constrain # of non-zero weights

$x$ is a known matrix, $y$ is a known vector, solve for $w$ (weights vector) given the following constraints. $w_1 x_{1,1} + w_2 x_{2,1} + \dots + w_n x_{n,1} = y_1$ $w_1 x_{1,2} + w_2 x_{2,2} + \dots + w_n x_{n,2} \geq y_2$ $w_1 x_{1,3} + w_2…
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Binary integer programming problem of a very specific form

The specificity of the problem lies in the fact that the objective function coincides with the left side of the only constraint. In other words: $$ \sum\limits_{i=0}^n a_i x_i \to \max, $$ $$ \sum\limits_{i=0}^n a_i x_i \leq…
user75619
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feasible region of a linear programming problem convex and concave

will the feasible region of a linear programming problem with linear mathematical relations and linear constraints, always be a convex polygon? will concave feasible regions have optimal value at corner points?
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Linear programing: Multiple slack variables

I have to convert folloving problem: $$ min\{|x_1| + |x_2| + |x_3|\ |\ \text{conditions..}\} $$ to linear program (if it is possible). Since $|x_1| = max\{x_1,-x_1\}$, i have: $$ x_1 \leq z_1 $$ $$ -x_1 \leq z_1 $$ $$ x_2 \leq z_2 $$ $$ -x_2 \leq…
Filip
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KKT conditions and feasibility of problems (P) and (D)

Let following linear problems: Primal Problem: \begin{eqnarray*} \textrm{Min}\quad c^T x & & \\ \textrm{s.t.}\quad Ax & \geq & b \end{eqnarray*} and its dual problem: \begin{eqnarray*} \textrm{Max}\quad b^T \lambda & & …
SKMohammadi
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LP: how to understand Duality and simplex

I am learning about Linear Programming right now.. I learned that we can use simplex to solve linear program and I also learned that every linear problem has a dual problem because of duality.. I am so confused now.. Since we can use simplex…
ZonghanXU
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