Name presolve

[4er4er4er]

MP should presolve and submit names to the solver / Reformulation Explorer when AMPL provides them.

Original title: Gurobi "writeprob" doesn't recognize "gurobi_auxfiles" setting.

With the ASL interface, it is possible to request the actual AMPL names in .mps and .lp files, by specifying

option gurobi_auxfiles rc;
option gurobi_options 'writeprob=export';

However, with the MP interface using these same options, only generic names (like R1 and C1) appear in the files. (This might not be specifically a Gurobi problem, but I haven't checked other solvers.)

• Var/con/obj name presolve added on 24 July 2023
• Redefinition value linking for unary encoding added
• Generic names are IMPL, IMPL_1_, IMPL_2_, ... for an original constraint/objective IMPL redefined into auxiliary items. This could be elaborated
• option writegraph should use names. This requires names presolve to be done during redefinitions, as the graph export goes
• Names for AMPL defined variables and items derived from them. Does AMPL provide these names?
• MP2NL Expression interface #237 has issues with reusing original names in MP subsolvers