Extending Planners
ZENO [Penberthy & Weld], IxTET [Ghallab & Laborie], HSTS/RAX [Muscettola] extend a conjunctive plan-space planner with temporal and numeric constraint reasoners
LPSAT [Wolfman & Weld] integrates a disjunctive state-space planner with an LP solver to support numeric quantities
IPPlan [Kautz & Walser; 99] constructs ILP encodings with numeric constraints
TGP [Smith & Weld; 99] supports actions with durations in Graphplan