# Tag Info

13

The implementation gap may not be a function of the "quality of the model" (or the algorithm used to solve it, which is a separate dimension). I had an experience with a logistics problem where the model was a simple shortest-path network model and the solution method was Dijkstra's shortest path algorithm. Both are time tested and thoroughly accepted. The ...

12

Here is a quick summary about the pros and cons of LocalSolver, a global optimization solver combining exact and heuristic techniques. Please note that this summary is written by the LocalSolver team itself, as asked by Kuifje in the comment above. Pros: You will model your problem using nonlinear and set-based mathematical modeling APIs. Then, your math ...

10

You asked two questions at the end and I only try to answer the second "why is it [implementation gap] not always included anyway": If I understand your question correctly, I'd say there can be many reasons why such an "implementation gap" that you refer to doesn't exist or reported. For example: The academic studies are not necessarily implemented. Why? ...

10

Ultimately, it depends on why you're doing the search. It also depends on what you mean by "coverage" - do you mean you want all papers that can be remotely considered OR/MS, or do you care about ensuring that you've captured everything from a specific (though potentially large) set of journals? Google Scholar is fantastic for broad coverage, and is my ...

10

For me, there is no substitute for Google Scholar. The main issue with our field is that it is pretty broad, so it is hard to tell where relevant publications might be. In many cases, the relevant literature might not be in an "operations research" journal. International Abstracts in Operations Research tried to handle that issue by collecting papers from ...

9

You are touching three similar but different subjects in your question. Choosing the set of parameter values for an algorithm and a set of instances is a task known as offline parameter tuning, algorithm configuration, or (as indicated in @EhsanK) hyper-parameter tuning (mostly in machine learning, where the term parameters means something else). There is ...

9

The problem you are referring to is hyper-parameter optimization and a simple search in google will bring up many blogs (and of course) research that has been done in this area. You haven't asked this, but since you mentioned a few algorithms (SA, Tabu search, ...), in case you are also interested to select the best algorithm for different data sets, then ...

8

It is not ideal, but sometimes I think the best you can do is utilize problem collections from published papers as benchmarks, even if their parameters are rather arbitrary (not necessarily based on industry experience). For example, there is a compendium by Oleg Shylo of experimental results for job shop problems at http://optimizizer.com/jobshop.php.

7

I agree with Dr. Trick that I tend to start with Google Scholar. If I'm looking to see what's been done since a paper was published, I'll often click the "cited by" option. Another option that may be helpful is the preprint site optimization-online.org. Sometimes I'll do a quick search there too.

7

Not a question, but switching to a reference management software has helped me a lot (Mendeley, in my case, but there are alternatives). In particular, the ability to tag papers with my own keywords, filter them based on my tags, and then sort them chronologically has helped me quickly get a better idea of the progress in specific areas of research. E.g. I ...

6

I'm going to interpret "in OR" as appearing in OR journals and/or written by people who identify as OR/MS/IE researchers. I'm a bit familiar with the intersection of optimization and statistical estimation. Machine learning, OLS and LAV regression, lasso regression etc. all rely on solving optimization problems to fit models. In addition, ...

6

It is common practice for MIP solvers to solve node LPs (other than at the root node) via dual simplex. I can't say with certainty that they terminate dual simplex prematurely if the objective value becomes inferior to the current incumbent, but I would think it likely. That does not address the question of stopping dual simplex early when the bound is ...

6

Yes, you can solve the dual and use that as a (weaker) bound than the optimal solution of the LP. This leads to the trade off between faster processing nodes vs processing more nodes. This approach is often exemplified in the choice between Lagrangean relaxation and Dantzig Wolfe decomposition. In its pure form you need to solve the DW to optimality in order ...

5

Very interesting notes about different alternatives. IMHO, it is not necessary a real-time or periodic scan of updates. Related to a particular topic you're researching, it may be enough to do a full "literature review" every, let's say, three or four months. However, to be aware of research trends in general, I like to read twitter (periodically), RG and ...

5

There was a similar question on Cross Validated and as in my comment there, I would look into the use of statistical experimental design, specifically factorial designs and fractional factorial designs. There is a very good book on that topic Box, Hunter & Hunter and here is a paper on its use in hyperparameter optimization Design of Experiments for the ...

5

To my understanding, the tuning process you just mentioned is also an learning technique where your training set is your set of representative instances. The problem is with generalization because your training has been too biased or representative set has not been a good training set. In parameter tuning, you may wish to do cross validations similar to ML. ...

5

The way I discover literature is to identify the key authors & papers in the field I'm interested in. From there on it's just a matter of following the citation trail. The influential authors/papers tend to be better written as well, which really helps when people are starting up.

5

One type of data that is likely to exist in many real-world applications is the so-called "ordered" data. In an ordered setting, if the processing time of a job $j$ is larger than that of another job $j'$ on machine $r$, then it is the case on all machines, that is, the jobs can be ranked based on their processing times. Also, there is the same relationship ...

4

Your problem looks like a quadratic assignment problem. The problem has been researched since at least the 1950s. As long as P$\neq$NP, there cannot be any constant factor approximation algorithm. I think there are some O(log(n))-approximation algorithms. There are also a number of well tested exact algorithms, that are better than brute force, and some ...

4

A generator of job-correlated, machine-correlated and mixed-correlated Permutation Flowshop instances is described in Watson et al. (2002)1 and can be found here. From the abstract: We introduce a method for generating structured flow-shop problems, which are modeled after features found in some real-world manufacturing environments. Another list of ...

4

It's unlikely that you will find a generalised study on this, as the predictive power of an optimisation model depends on the accuracy of the data we use to build the model, and on the skill of the modeler themselves. This is also compounded by the fact that the predictive power of a model is also dependent on the solver we use, in particular on whether the ...

4

In solving optimization problems, the gap is a relative concept. In the academic papers, the authors, have often used small instances to represent the model under study and usually, they could solve them optimality with a small gap. Indeed, in the real-world problems (specifically, supply chain or scheduling) the problem is large, and the solution might be ...

4

In reverse chronological order, here are some papers which use OR (or OR-related) techniques to solve problems in evacuation planning: Goerigk, Marc et al. "Ranking robustness and its application to evacuation planning." European Journal of Operational Research 264.3 (2018): 837-846. Swamy, Rahul et al. "Hurricane evacuation planning using public ...

4

A buzzword that comes to my mind are Flows over time and especially Earliest Arrival Flows. Martin Skutella and students of his have worked out a bit of theory for that, see e.g. An introduction to Network Flows over time, Earliest Arrival Flows with multiple sources, Earliest Arrival Flows with multiple sinks.

3

My recommendation is to use something like https://scirate.com/ or even Mendeley also provides recommendations if you have built up a reference list.

3

Excluding papers listed in other answers... Surveys: Great starting points would be surveys on general evacuation and disaster operations management such as Hamacher & Tjandra (2002) and Dhamala (2014) for time-expanded network flow models. Wright (2006) gives a homeland security-themed survey. General Evacuation: Multiobjective evolutionary algorithm ...

3

Goerigk et al. (2014) may be a good start to your literature search. It uses mixed-integer programming to propose a genetic algorithm that can be used for urban evacuation planning. Examples of scenarios are provided at the end. A bonus of this paper is that it already contains an extensive literature review in section 1.2. Reference [1] Goerigk, M., ...

3

I think the Business Value Added is a general concept and could be translated as a specific term/definition in the manufacturing, services or another real-applications era. For example, in the manufacturing field, it might be defined as, any improvement in each step of producing a product. Also, it can be represented as, value-added, measures the amount of ...

3

A common case where you would see 2 or more exponentially large sets of variables, is in: VRPs with heterogeneous vehicles: some vehicles have special equipment or larger capacity and can serve different types of routes Rostering problems with employees with different skills: some employees can perform skills that others cannot perform (e.g. drive a ...

3

The state-of-the-art method for solving the vehicle routing problem with split deliveries is in fact LBBD as can be seen in the following papers: https://www.sciencedirect.com/science/article/abs/pii/S037722171400352X https://pubsonline.informs.org/doi/abs/10.1287/trsc.2018.0825 Although the authors do not refer to their algorithms as LBBD, their methods can ...

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