etienneandre / polyop

Operations on Polyhedra (simple layer on PPL)

PolyOp

Operations on polyhedra

v 1.4

Operations on non-necessarily closed, non-necessarily convex polyhedra: (relatively) simple layer on the Parma Polyhedra Library (PPL), with some hopefully useful additions. All operations use the Pointset_Powerset NNC_Polyhedron data structure from PPL

Some of the operations allowed by PolyOp:

• intersection
• union
• difference
• negation
• satisfiability
• time elapsing
• time backward-elapsing ("past")
• variable elimination (by existential quantification), or projection onto a variable set
• Boolean tests (inclusion, equality…)
• updates of variable (i.e., replacing their value with a linear combination of variables)
• exhibitpoint: exhibition of a concrete point in the polyhedron
• zonepred: computation of the predecessors of a subset of a zone within a source zone (given the set of variables subject to time-elapsing (typically clocks), and the set of variables reset between the two zones); this function is typically useful to reason about parametric zones in parametric timed automata or parametric time Petri nets [not sure this function corresponds to an actual problem in PTAs / PTPNs]
• zonepredgu: Given Zn-1 and Zn such that Zn is the successor zone of Zn-1 by guard g-1 and updating variables in Un-1 to some values, given Zn+1 a set of concrete points (valuations) successor of zone Zn by elapsing of a set of variables t, by guard gn, updates Rn, then zonepredgr(Zn-1, gn-1, Un-1, Zn, t, gn, Un, Zn+1) computes the subset of points in Zn that are predecessors of Zn (by updates of Un, guard gn, elapsing of t), and that are direct successors (without time elapsing) of Zn-1 via gn-1 and Un-1. This function can typically used when running a backward analysis in a zone graph of a PTA / PTPN.

From version 1.0, several operations can be performed sequentially using the same call to PolyOp

Basic call syntax:

polyop examples/example.polyop

See examples of the input syntax in examples/example.polyop.

(Some more examples in tests/testcases/)

For any information, please feel free to contact me:

https://lipn.univ-paris13.fr/~andre/