# All Questions

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### Matlab fmincon for a problem with many nonlinear constraints

Using Matlab to solve a problem which has linear objective function and many nonlinear constraints, I am trying to generate the inequality nonlinear constraints by a function and pass it to fmincon ...
60 views

### Using Spatial Multi Criteria Analysis for simultaneously locating various facilities?

Is it possible to use SMCA (Spatial Multi Criteria Analysis) for determining simultaneously where to locate various facilities? Suppose, for example, I'm planing to build a new city and everything ...
49 views

### Understanding the AMPL Solver LIbrary within Pyomo

For anyone familiar with the Pyomo book, it occasionally makes reference to the AMPL Solver Library, and to my understanding, if you can manage to hook up to the solver library then you are able to ...
251 views

### Finding an Objective Function for Assigning Employees to Sequence Dates

I am using a mixed-integer-program to schedule employees to projects. These projects can have a time window to get completed from a few weeks to a few months. At the moment I am working in a ...
79 views

When using DOCplex to implement column generation, is it possible to add columns as an object, as opposed to creating a variable and then modifying the coefficients in the constraints? Edit: In ...
56 views

### Problems Installing APOPT in Pyomo

I am trying to install the solver "APOPT" in Pyomo by following the guidelines laid out below: *Instructions for usage: Place apopt.py in an appropriate folder in the system path (e.g. Linux, /usr/...
70 views

### How to model 24 hours demand into a daily shift schedule?

I am working on a weekly staff scheduling optimization problem with 24/7 demand. The binary decision variable is: $X_{\text{staff},\,\text{day},\,\text{shift}}$ whether to assign the staff $s$ to day ...
341 views

### How to formulate a problem to prove/disprove convexity?

Given a general non-linear problem: \begin{align}P:\qquad&\min_{x\in X} f(x)\\\text{s.t.}\qquad&g(x)\leq 0\end{align} where $f$ is a non-linear function, $g$ is a vector of non-linear ...
406 views

### Case Studies and Real Problems for Teaching Optimization and Modelling

It is that dreadful time of the year when I am prepping classes and over the last few terms I came to the realization that I need to significantly beef up the practice-oriented content of my lectures. ...
294 views

### Are there NP hard problems solved in P time?

Does anyone know of a problem previously believed to be NP hard, to be solved nowadays in polynomial time optimally?
166 views

3k views

### Are there any OR challenges that are similar to kaggle's competitions?

I am looking for previous OR challenges. My goal is : Applying my knowledge while solving problems suggested in those competitions; and/or If possible, reading solutions posted by participants. I ...
380 views

### Expressing a chain of boolean ORs using ILP

How to express a chain of OR operations in an ILP in which each expression is a less than or equal constraint and the left hand side variable in all inequalities is always the same? All the variables ...
102 views

### Real world demand dataset

I am looking for a publicly available real world demand data to compare the performance of some algorithms. The dataset should include some products with data of a sufficiently long period of time. I ...
197 views

### Generating all extreme rays

I am trying to understand a problem and would like to generate all extreme rays for a given set of linear constraints. With the Python interface of CPLEX, I was able to generate a single ray (not sure ...
Can you help me identify if this technique has a standard name to help me explore the literature? Suppose I have a black-box stochastic simulation parameterised by $X=[x_1,...,x_p]$ with some single ...