# Questions tagged [optimization]

For questions involving mathematical problems that aim to minimize or maximize some objective function, possibly subject to one or more constraints.

513 questions
Filter by
Sorted by
Tagged with
114 views

### how to apply Big M to model the logic constraint （if-then-else）

I was hoping to get some help in modelling the following logic as an MIP Constraint c_{m,l}^{RC} is binary decision variable. Simplify it：
83 views

198 views

### Output of binary variable greater than one

I am working on a shipping demurrage problem that uses a binary variable to denote the date a specific vessel can be loaded (I have been kindly helped by Wesley on OR before with this). I am confident ...
138 views

### Limit number of switches in employee scheduling problem

Here is a scheduling problem I need to solve. Given the demand for 2 positions in 1 week with 3 shifts per position, I need to allocate the employees accordingly with some extra operational ...
46 views

### Algorithm for Trainyard Marshall optimization problem

The problem I am trying to solve is the 2014 RAS problem. The link is the following The problem Trains come to the humpyard where each compartment of a train gets humped or disassembled and then each ...
119 views

### How to optimize with “if” constraints

The minimizing problem is the following : $$\underset{w}{\operatorname{argmin}} \sum_{i=1}^{n}\left[w_{i}\times (\frac{Vw}{\sigma})_{i} - b_{i}\right]^{2}$$ with $V$ a $n\times n$ matrix (covariance ...
55 views

### How to deal with the sub-problem with zero reduced cost in D-W decomposition

The specific linear programme has an optimal solution as $x_1 = 0.66$, $x_2 = 1.33$, $x_3 = 12.2$, $x_4 = 0.0$ and the objective value is $33.3$. While the problem is solved by D-W decomposition ...
147 views

### A more efficient way of solving an peculiar optimization problem

Given the table ...
133 views

### Representing Date Variables in Pulp

I am working on an optimisation problem that involves minimising shipping demurrage. I am struggling to model how to represent the difference, (x-y) between dates where the ship is ready to be loaded ...
46 views

### Decision-making algorithm for dynamic load balancing

I'm researching a subject of balancing the load between two black-box systems (with some twists). I thought that I could record latest response time log from each of those systems and process such a ...
778 views

### Fast algorithm for Transportation Problem in Python?

The Transportation Problem can be solved with a simplex algorithm, but it's time-consuming. I'm wondering if there exists a specific Python-implemented algorithm with low complexity.
133 views

### Resource constraint with MIP model

My question is how to model a resource constraint with MIP model (how should I modify it?) A factory is making blocks. If there is space left at that time, the block can be assembled. (If the factory ...
2k views

### An approximate answer to the right question or an exact answer to the wrong question

There is a quote from John Tukey in one of his papers on data analysis Far better an approximate answer to the right question, which is often vague, than an exact answer to the wrong question, ...
236 views

### Creating an Optimisation Problem to Optimise Water Flow

A water tank needs to be refilled with an electric pump when the water level gets below a certain level. The pump can operate at variable flow rates. Further, there is a time-variant electric billing ...
152 views

### Pulp Python: How to formulate a time-based variable for shipping demurrage

I am working on a shipping optimisation problem that aims to minimise demurrage charges as a result of low/insufficient inventory. I have daily vessel requirement (sales) data in the format ...
202 views

### Convert summation of min functions into linear constraints for optimization

I have the following optimization problem:  \mbox{maximize } j^{*} \mbox{ subject to:} \sum_{j^{*}\leq j\leq J} \min({\bf A}_j,{\bf B}_j) \geq \lambda, \lambda \in \mathbb{R} \mbox{ and } {\bf A}_j,{...
321 views

### How to allow multiple assignments for jobs in Hungarian Algorithm?

In the Hungarian Algorithm, the assignment for a bipartite graph considers the restriction of assigning a single job to a single person for example. Can this restriction be relaxed? I would like to ...
2k views

### How to convince people that OR can help them?

When talking to people who are not familiar with what OR is and what it is about, and you want to convince them that it might be useful for them/their industry, what do you tell them in order to ...
197 views

### Defining and comparing utilization rates for delivery service

I'm currently working on a case for a food delivery service and wondered whether my notion of "driver utilization" makes any sense. My data set contains an hourly overview of the number of active ...