Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.

When I set option substout 1, why doesn AMPL make the substitutions that I expect?

April 26, 2017ampl expect option substitutions

0

Posted

When I set option substout 1, why doesn AMPL make the substitutions that I expect?

1 Answer

0

Posted

A variable is ineligible to be substituted out of a problem if (a) it is subject to any bounds or integrality conditions, or (b) it has already appeared on the right-hand side of a constraint that was used to make a substitution. Case (a) includes bounds or integrality conditions specified in the variable’s declaration, and also bounds that are added by AMPL’s presolve phase. Thus turning presolve off (by setting option presolve 0) may permit a greater number of substitutions. For constraints indexed over a set, the incidence of case (b) may depend on the ordering of the set.