Z3: an exception with int2bv

Question

(declare-const a Int)
(declare-const b Int)
(declare-const c (_ BitVec 32))
(declare-const d (_ BitVec 32))

(assert (= b (bv2int c)))
(assert (= c (int2bv a)))

(check-sat)

I am confused about the exception "int2bv expects one parameter" caused by the code above, how to use function int2bv correctly?

Answer 1

This is because int2bv is a parametric function and the SMT2 syntax for these is (_ f p1 p2 ...), so in this case the correct syntax is

((_ int2bv 32) a)

Note that int2bv is essentially treated as uninterpreted; the API documentation says:

"NB. This function is essentially treated as uninterpreted. So you cannot expect Z3 to precisely reflect the semantics of this function when solving constraints with this function." (from here)