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1500 questions
5
votes
4 answers
How to visit a subset of network nodes in a single trip?
I have a connected network where I want to visit a set of destinations which may require visiting intermediate nodes as well because there may be no direct edge between source and destination nodes. I want to visit all destinations including…
bsha
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5
votes
1 answer
How to set a limit for a switch to 0 of a variable for 2 variables combined
I have a follow up question to another question of mine How to set a limit for a switch to 0 of a variable about counting the number of switches to 0 of one decision variable. Now I would like to ask the same question for two combined decision…
PeterBe
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5
votes
1 answer
How to set a limit for a switch to 0 of a variable
I would like to know how to define a constraint to set a limit for switching to 0 for a decision variable? So I have a linear variable $x(t)$ which quantifies the modulation degree of a heating device. It can be between $0$ (meaning that the device…
PeterBe
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- 30
5
votes
2 answers
find suboptimal solution, if no optimal solution exists?
I am using or-tools linear solver. and my problem ends up having no optimal solution. how can I tell the solver to find a suboptimal solution?
Hisham Al Kayed
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5
votes
1 answer
How to add a SOS1 equality constraint?
Most MIP solver's API have special methods to add SOS1-constraints of the form
$$ \sum_{i \in I} c_i x_i \leq 1, \tag{1}$$
i.e. at most one of the binary variables $x_i, i \in I$ is allowed to take a non-zero value. As far as I know, writing $(1)$…
Ronaldinho
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5
votes
1 answer
how to implement an optimization function with polynomial in Gurobi (Java)
I have the following problem:
I have an objective function with the optimization variable $x$, which looks simplified like this:
$ZF = (a+b)*(x+1)$
Here $a$ is simply a constant value.
However, behind $b$ is a 4th degree polynomial which is…
Handballer73
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5
votes
1 answer
Maximize number of backups that fit on backup drive
This is an intrinsically "practical" question, but it leads to a well-defined mathematical problem. Let me start with the practical part:
I regularly back up my data. My backup strategy are differential backups, where the first backup is a full…
CL.
- 153
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5
votes
1 answer
Discontinued function optimization
I am struggling with transport optimization problem, that simplified might stated as:
Minimize the number of bananas transports to the shop in the following 5 days (transported_bananas = [n1_bananas, n2_bananas, n3_bananas, n4_bananas,…
jacekblaz
5
votes
1 answer
Incomplete initial solution for capacitated vehicle routing problem
I am solving Capacitated Vehicle Routing Problem (CVRP) with Adaptive Large Neighborhood Search (ALNS) metaheuristic.
I start my algorithm with a random initial solution, but the solution I get is incomplete. There is a node that has not been…
userB
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5
votes
0 answers
Reference request — fishery yield optimization
I'm looking for references to do a review of research on managing fisheries in industry. I've seen adaptions of
population growth models which include some harvesting constant or function and was wondering what has been done in the area,…
Ryan Howe
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5
votes
0 answers
Bounding the size of the dual solution
Given an primal optimization with bounded feasible set: $\max \{cx: Ax \leq b\}$.
The feasible region of the dual is $D = \{y:y^\top A = c^\top, y \geq 0\}$.
If the primal feasbile region is a polytope, then the dual might still by an polyhedron…
user3680510
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5
votes
1 answer
NP-hardness of a special case of multiple choice knapsack problem
Let us consider the following problem:
\begin{align}
\max &\quad\sum_{i=1}^n\sum_{j=1}^m v_{i,j}\cdot x_{i,j} \\
\text{s.t.}&\quad \sum_{i=1}^n x_{i,j} =1 &\forall j =1,\dots,m \\
&\quad \sum_{i=1}^n\sum_{j=1}^m w_i\cdot x_{i,j} = W & \\
&\quad…
Pete S
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5
votes
2 answers
Piecewise linear and global optimization
I am new to OR, and apologies if my mathematical notation is not clear. I have tried my best to keep it concise and given an explanation with numerical data.
I would like to understand:
Can this model be formulated as convex, such as piecewise…
Marry
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5
votes
2 answers
Safety Stock with Fill Rate Criterion
When applying the base stock inventory policy, assuming the daily demands are normally distributed with parameter $(\mu, \sigma)$, we can find the optimal parameter $S$ (the base stock level) in several different ways: (say we have 0 lead time and…
TTY
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5
votes
0 answers
Materials or sample code for column generation book (GERAD 25th Anniversary Series)
As far as I know, one of the interesting resources to learn the basic concept of the decomposition methods is column generation book (GERAD 25th Anniversary Series), which has been mentioned in some useful community Q&A like this, but unlikely there…
A.Omidi
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