Unretractable assertions outside of check-sat-assuming
Revert to old way of representing negative numerals/decimals in Kind. The invariant is that numerals/deciamls in term should always be positive. Special encoding for yices to overcome unary minus restriction : print -a as 0 - a.
Use set-artih-only in Yices when flag --yices_arith_only is passed but fail when it is not safe.