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usi-verification-and-security / opensmt

The opensmt solver
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Opensmt rejects non-linear integer arithmetic too eagerly #655

Open aehyvari opened 8 months ago

aehyvari commented 8 months ago

Opensmt throws a LANonLinearException on this instance. It'd be nice if it didn't. Maybe we should somehow tell ArithLogic when it is parsing a define-fun to ignore the nonlinearities.

(set-logic QF_LIA)
(define-fun uninterp_mul ((a Int) (b Int)) Int (* a b))
(assert (= (uninterp_mul 1 2)))
(check-sat)
(exit)
blishko commented 8 months ago

I think this is not going to be easy in the current implementation. The code of ArithLogic assumes we do not create nonlinear expressions.

I see two ways forward here, both of which would be good to have, eventually. One is a change in the frontend, which would use a new term data structure that would follow closely the term grammar of SMT-LIB, and we would translate that to PTRef during some internalization process. Second change is to actually start supporting nonlinear arithmetic, at least in the term representation.