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1500 questions
6
votes
0 answers
Help in solving resource allocation optimization problem
I've been pondering on this question for some work optimization, and I need some help in being directed to the right direction.
I have multiple customers that require an amount of $X$, $Y$ and $Z$ each. From the factories, I have a number of trucks…
Sylicas
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6
votes
1 answer
Network flow model - How can I turn this diagram into a matrix that when converted to RREF solves for max flow?
I have the following network flow model diagram and I have already calculated maximum flow using the R package igraph to be 28. However, what I would like to know how to do is to solve this for maximum flow using the simplex method of linear…
Jacob Myer
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6
votes
1 answer
How To Linearize $X = \max\{x_1,x_2\}$
I am new to thinking about math programming and I have a particular constraint I am hoping to reformulate, I just don't know the proper mathematical translation for what I am hoping to do. Enforcing the non-negativity constraint on $X$ in Constraint…
GrayLiterature
- 2,309
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- 27
6
votes
1 answer
Calculating realization ratio of a value related to a target where lower values are more interesting
I want to calculate realization ratio of a value related to a target when lower values are considered better, in one special case the goal is zero.
To make my problem more clear, there is a complete use case…
Reza Afzalan
- 163
- 5
6
votes
2 answers
Solving a Certainty Equivalent (Decision Analysis) problem
I am solving a Certainty Equivalent (Decision Analysis) problem.
The problem is a Risk-Averse Case - a deal of $60\%$ chance to win $\$100,\!000$ and $40\%$ chance to lose $\$10,\!000$.
Suppose the decision-maker is risk-averse with a risk tolerance…
Mark K
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6
votes
1 answer
How to decide the hiring headcount for a retail department
The job responsibility is exactly the same in the department.
The department has a total number of working hours required.
The total retention is about 50% a year, and the hiring cost is about $2000 per person.
Salary is about $12 per hour. Full…
janicebaratheon
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6
votes
1 answer
How can I solve this problem?
I have $N_{\rm C}=8,$ and $N_{\rm U}=25$
Scenario 1:
$$\frac{l_{c,u}}{\sum\limits_{c=1}^{N_{\rm C}}l_{c,u}}\ge 0.1,\quad\forall u,u=1,2,\cdots,N_{\rm U}$$
and
$$\sum_{u=1}^{N_{\rm U}}l_{c,u}\le 1,\quad\forall c,c=1,2,\cdots,N_{\rm C}$$
For each…
KGM
- 2,265
- 7
- 23
6
votes
1 answer
DAG shortest path in R - I have a list of nodes, each node's completion time and each node's predecessor(s). How can I turn this to a list of arcs?
Without trying to manually sketch out a graph on paper, is there a simple way I could get the arcs between nodes in this problem? I am using R and it seems there must be an elegant way of doing so but I'm at a loss. I'm going to need to be passing…
Jacob Myer
- 447
- 3
- 8
6
votes
0 answers
What are the top three applications (in terms of number of citations) of the "reverse search" algorithm of David Avis?
I can see that this algorithm is quite popular, and that one of the original papers now has 820 citations on Google Scholar. However, what are the most highly cited applications of it?
If in Google Scholar I click on a paper about the reverse search…
Nike Dattani
- 1,278
- 6
- 32
6
votes
2 answers
What Exactly Is A Warm Start?
I am fairly new to optimization modelling but I am encountering a situation in which I supply initial values to my problem and then after I run my optimization those initial values change. This seems counter-intuitive to me though because if the…
GrayLiterature
- 2,309
- 7
- 27
6
votes
2 answers
Three newsvendor functions, three optimal solutions—which is correct?
Here is a typical setup for the newsvendor problem:
The newsvendor buys newspapers for $c$ each, sells them for $r$ each, and salvages unsold newspapers for $v$ each. The demand distribution has pdf $f(x)$ and cdf $F(x)$. What is the optimal order…
LarrySnyder610
- 13,141
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- 105
6
votes
1 answer
Obtaining the intermediate solutions in AMPL
I know that for some solvers, for example, the constraint programming solver in Google OR-Tools, it is possible to see all the intermediate solutions that the solver finds while it searches for an optimal solution. (An example is in this link.) I…
Oguz Toragay
- 8,652
- 2
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- 41
6
votes
2 answers
How to add Binary Variable with condition in LP
Notation
$\text{src}_{h,s},\text{dst}_{h,s},\text{ch}_{h,s}$ are constants.
$a_{h,s},x_{i,j,s}$ are binary variables.
$\text{wt}_{h,s}$ are continuous variables.
Problem
\begin{align}\min.&\qquad\sum_{h \in H}\sum_{s\in…
ooo
- 1,589
- 4
- 12
6
votes
2 answers
Linearization of objective function
Notation
$\text{src}_{h,s},\text{dst}_{h,s},\text{ch}_{h,s}$ are constants.
$a_{h,s},x_{i,j,s}$ are binary variables.
$\text{wt}_{h,s}$ are continuous variables.
Problem
\begin{align}\min.&\qquad\sum_{h \in H}\sum_{s\in…
ooo
- 1,589
- 4
- 12
6
votes
3 answers
Can determining the unique fixed point of a function be posed as an optimization problem?
Consider the function $f : \mathbb R \to \mathbb R$, which has a unique fixed point $x^* \in \mathbb R$, such that $x^* = f(x^*)$ and there does not exist another $x \in \mathbb R$ such that $x = f(x)$. If we only knew that $f$ had a unique fixed…
mhdadk
- 609
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