v1.28.1

GAMSPy 1.28.1 (2026-10-02)

New features

• #911: Added indicator formulation to gamspy.formulations for modeling indicator constraints, either reformulated or passed to the solver natively.
• #913: gp.If, gp.ElseIf and gp.Else can now be used on the outermost level, and gp.If and gp.ElseIf accept an optional container argument.

Improvements in existing functionality

• #898: gamspy list solvers now shows a reduced, more readable table of solvers and tools, with a status column (licensed/installed) and one column per supported problem type, instead of a plain solver-to-problem-type listing.

Bug fixes

• #904: Indexing a symbol with a set that an enclosing operation binds to a literal element, e.g. Sum(i["label"], p[i]), no longer raises a false domain violation.
• #910: Corrected the equation list for the cperfect model and several incorrect import statements in the inlined example models.
• #914: Model attributes are now set after solving a model inside gp.Loop, gp.For or gp.While.

Improved documentation

• #901: Rewrite the section on logical operators for better readability.

Deprecations

• #898: The examiner2 solver is deprecated and will be removed in a future release. Model.solve(solver="examiner2") now emits a DeprecationWarning and gamspy install solver examiner2 prints a deprecation warning; use examiner instead.
  gamspy list solvers --installables (-i) is deprecated and will be removed in a future release; it now prints a deprecation warning. Use gamspy list solvers --all instead.

Miscellaneous internal changes

• #909: Move the socket connection to the GAMS process behind an execution engine abstraction to prepare the way for adding alternative local execution engines in the future.