# Tag Info

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### Why is it important to choose big-M carefully and what are the consequences of doing it badly?

The following answer presumes some familiarity with the limitations of floating-point arithmetic (rounding, truncation and representation errors), which I will lump together as “rounding error”. It is ...
• 39.8k
Accepted

### What is the "big-M" method? And are there two of them?

People do use the term "big-$M$ method" to mean two different things. In both cases, the name refers to the use of a large constant, often denoted $M$. The first use of the term refers to a method ...
• 13.1k

### When to use indicator constraints versus big-M approaches in solving (mixed-)integer programs

Here is the advice in the IBM CPLEX documentation. So this pertains to CPLEX. I don't know to what extent it applies to other solvers. First of all, indicator constraints may not be available in all ...
• 13.5k

### Single reference for Mixed Integer Programming formulations to linearize, handle logical constraints and disjunctive constraints, do Big M, etc?

Here is a nice, succinct, and easy to understand reference for how to do all this and more. Answers to many future questions can be handled by referencing the appropriate section number in this ...
• 13.5k
Accepted

### When to use indicator constraints versus big-M approaches in solving (mixed-)integer programs

For Gurobi there seems to be a dual advantage of using general constraints (http://www.gurobi.com/documentation/8.1/refman/constraints.html#subsubsection:GeneralConstraints): Benefit number one - ...
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### When to use indicator constraints versus big-M approaches in solving (mixed-)integer programs

To the best of my knowledge the indicator constraints are just syntactic sugar for the user. Internally these indicator constraints are reformulated using computed big-M formulations or SOS ...
• 2,767

### Why is it important to choose big-M carefully and what are the consequences of doing it badly?

Tightening the big-M is very important, but sometimes this is done in a reasonable way by the automatic MIP preprocessor. If you want to see how the BigM in the input model is automatically tightened ...
• 1,696