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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Determining information in minimum trials (combinatorics problem)

A student has to pass a exam, with $k2^{k-1}$ questions to be answered by yes or no, on a subject he knows nothing about. The student is allowed to pass mock exams who have the same questions as the real exam. After each mock exam the teacher tells…
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Shadow prices in linear programming

I am quite confused about the meaning of shadow price from explanations on the internet. It can be understood as the value of a change in revenue if the constraint is relaxed, or how much you would be willing to pay for an additional resource. For…
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Linear Programming Books

Do you know of a good book on linear programming? To be more specific, i am taking linear optimization class and my textbook sucks. Teacher is not too involved in this class so can't get too much help from him either, Any help will be…
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Why does the maximum/minimum of linear programming occurs at a vertex?

I'm in high-school and I'm told that the maximum/minimum of a linear programming occurs at the vertex.For more info see the chapter here. For convinience I'm putting relevant excerpt here: Now, we see that every point in the feasible region…
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Converting absolute value program into linear program

I have the generic optimization problem: $$ \max c^T|x|$$ $$ \text{s.t. } Ax \le b $$ $x$ is unrestricted How do I convert it into a linear programming problem? Online I read something about letting $x$ equal the difference of 2 positive numbers…
Sidharth Ghoshal
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How the dual LP solves the primal LP

When I heard someone discussing LP the other day, I heard him say, "Well, we could just solve the dual." I know that both the primal LP and its dual must have the same optimal objective value (assuming both are feasible and bounded). I also…
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What are the advantages of studying the dual problem in linear programming?

I am studying linear programming and I came across primal-dual algorithm in Linear Programming. I understood it but I am unable to understand why there is a need to calculate a dual, if problem can be solved in primal space. Are there some inherent…
Aman Deep Gautam
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Optimum solution to a Linear programming problem

If we have a feasible space for a given LPP (linear programming problem), how is it that its optimum solution lies on one of the corner points of the graphical solution? (I am here concerned only with those LPP's which have a graphical solution with…
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Good software for linear/integer programming

I never did any linear/integer programming so I am wondering the following two things What are some efficient free linear programming solvers? What are some efficient commercial linear programming solvers? It would be nice to supply a dummy…
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How low can the approval rating of a majority candidate be?

“Ostrogorski's paradox” describes a strange situation in which voters decide on candidates based on issues in platforms, but on each issue of the platform, the majority of voters disapprove of the majority winner. What is the lowest possible…
Jack Schmidt
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What is linear programming?

I asked this question on Stack Overflow but it was closed as "not programming related". So I think this is probably the best place for it... I read over the wikipedia article, but it seems to be beyond my comprehension. It says it's for…
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How can not-equals be expressed as an inequality for a linear programming model

I have this linear programming model I'm building but one of the constraints needs to specify that the solution's basic variables need to all be different from one another. This is an integer linear program. How can we rewrite, for example, this…
Geoffrey Anderson
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What is the computational complexity of linear programming?

What is the computational complexity of solving a linear program with $m$ constraints in $n$ variables?
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Polygons with 2 diagonals of fixed length (part two)

In this question of mine Polygons with two diagonals of fixed length I've presented the following particular polygon $P$ and I've asked the following question: is it possible to shorten one or more sides or blue diagonals of $P$ in a continuous…
user372511
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Variable leaving basis in linear programming - when does it happen?

In the simplex algorithm in linear programming, what are conditions for a variable to leave a basis (not necessarily basis for the/an optimal solution)? I'm supposed to list as many sufficient and necessary conditions as possible for some basic…
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