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:

5084 questions
1
vote
1 answer

Linear equation system to standard form

So I have this linear equation system: $inf \{3x_1 - x_2 - 2x_3 + x_4\}$ $x_1 + 4x_2 - x_3 - 3x_4 ≤ 3$ $-2x_1 + x_2 + 2x_3 - x_4 ≥ -1$ $5x_1 - 3x_2 + x_3 + 2x_4 ≤ 4$ $x_1 ≥ 0, x_2 ∈ R, x_3 ≤ 0, x_4 ∈ R$ And I have to bring it to its standard…
1
vote
1 answer

Is this a correct formulation of a linear programming problem?

I apologise as English is not my first language so sometimes I get stuck on problems like these as it can confuse easily. Show & Sell can advertise its products on local radio and television (TV). The advertising budget is limited to £10,000 a…
1
vote
1 answer

Linear Programming, with slack variables

I'm trying to prove the following statement Show that the set ${\{(x,w) \in \mathbb R^n\times \mathbb R^m \mid Ax \leq0, c^T x >0,w^TA=c, w\geq0 \}}$ is empty, where $A\in \mathbb R^{m\times n}$ and $ c \in \mathbb R^n$ are given.
user00
  • 55
1
vote
1 answer

Solving Linear Optimization Problem with Shortest path Algorithm

A little while ago I read a wiki about alternating between linear programming and shortest path problem (https://en.wikipedia.org/wiki/Shortest_path_problem#Linear_programming_formulation). I'm just starting to learn linear optimization, and i can't…
1
vote
1 answer

Linear Programming Diet Problem

I'm just starting to explore linear programming in Excel and have hit a VERY newbie problem I'm sure. I'm using it to optimise a "diet" plan with a few ingredients. The problem I've hit is as follows. What I'd like to do somehow is limit the number…
Dan
  • 293
1
vote
0 answers

Dual and Primal in Linear programming.

I am stuck on these two questions. I have tried to get information on these but what am getting is not even close to the questions. What can you say about the dual if you already know that : an optimal solution to the primal exists with x1 = 0? an…
Ben
  • 167
1
vote
1 answer

Use duality to solve LPP

I have some confusion regarding the solution of LPP by solving its dual. I have drawn the following table to indicate possibility/possibilities. I have made an attempt to correlate the two columns but much doubt regarding its correctness. Please…
1
vote
0 answers

Mathematical formulation of LPP

I want to formulate the following problem as a LPP A manufacturing company produces two types of computer monitor- color and monochrome. The data in the manufacturing context are as follows 6 days are required to complete one unit of each type of…
1
vote
1 answer

Finding a linear programming model

Question: Acme manufacturing company has contracted to deliver home windows over the next 6 months. The demands for each month are 100, 250, 190, 140, 220, and 110 units, respectively. Production cost per window varies from month to month depending…
1
vote
2 answers

Linear Programming Word Problems

A bakery has bought 250 pounds of muffin dough. They want to make waffles or muffins in half-dozen packs out of it. Half a dozen of muffins requires 1 lb of dough and a pack of waffles uses 3/4 lb of dough. It take bakers 6 minutes to make a…
1
vote
0 answers

Simplex method with zero value constraints

The usual problem is to maximize some linear function $f(x_0, x_1 ... x_n)$ subject to linear constraints $g_i(x_0, x_1 ... x_n) \leq b_i$. My question is: What happens when all (or most) of the $b_i$ are zero? You start with a basic solution which…
James
  • 11
1
vote
1 answer

Best basic feasible solution NOT optimal solution to LP

Assuming that we are working with a minimization objective function and we have identified the best basic feasible solution, i.e. the basic feasible solution that yields the most minimal objective value, when is this best basic feasible solution NOT…
1
vote
1 answer

Bounded feasible region condition

Suppose $M=\{x \in \mathbb{R}^n: Ax \ge b\}$ is nonempty and $x_0 \in M$. Prove that $M$ is unbounded, then there exists a vector $d \in \mathbb{R}^n$, such that $x_0+\lambda d \in M,\forall \lambda \ge 0$. I can prove it with duality theorem, but I…
T. Huynh
  • 111
1
vote
2 answers

Constraint Set of Canonical Linear Programming Problem is Convex

I'm reading through my first textbook on linear optimization. The book states a theorem without proof and I'd like to understand why it's true. Glossary of Terms: Definition 1 The problem Maximize…
1
vote
1 answer

What is the dual problem in linear programming

In linear programming, Von Neumann define the dual of $$(I)\, \left\{ \begin{array}{rl} c^Tx &\to \min\\ Ax &\ge b\\ x&\ge 0 \end{array} \right. $$ is the problem $$(II)\, \left\{ \begin{array}{rl} b^Ty &\to \max\\ A^Ty &\le…
T. Huynh
  • 111