We introduce the notion of porous invariants for multipath (or branching/nondeterministic) affine loops over the integers; these invariants are not necessarily convex, and can in fact contain infinitely many 'holes'. Nevertheless, we show that in many cases such invariants can be automatically synthesised, and moreover can be used to settle (non-)reachability questions for various interesting classes of affine loops and target sets.
Proceedings of CAV 21, LNCS 12760, 2021. 31 pages.
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© 2021 Engel Lefaucheux, Joël Ouaknine, David Purser,
and James Worrell.