Nonlin LA preds

[BritikovKI]

Allows to create nonlin functions

Removed all of the constraints for the creation of nonlin predicates inside of the functions.
Only the assertions are checked for nonlinearity

[aehyvari]

The code fails with this input

(set-logic QF_LIA)
(define-fun uninterp_mul ((a Int) (b Int)) Int (mod a b))
(assert (= (uninterp_mul 1 2) 0))
(check-sat)
(exit)

Here's the output:

(error "Divisor must be constant in linear logic")

(error "define-fun returns an unknown sort")

(error "Unknown symbol `uninterp_mul Int Int'")

(error "assertion returns an unknown sort")

sat

[aehyvari]

For our limited form of axioms this might actually be just enough. One thing is missing before I can put this to our production: To be sure that we're running the correct version, I'd need to have the version information from opensmt. See issue #800 .

[BritikovKI]

Ok, I think generally PR is over

Though, we definitely need some sort of error handling, LANonLinearException produces errors with different format under different complilers rn. Should it be a different issue though?

[BritikovKI]

isNonlin is temporarily needed, we don't do RealDiv refinement in the DivModRefinement because we expect originally that by the time of refinement RealDiv no longer exist in the instance(removed during parsing). So we need to check if there is nonlin RealDiv in the formula as well as multiplication...

[blishko]

Note to myself. It would be good if we can avoid this complicated piece of code. It feels like the code in simplify should take care of most of this.