(get-unsat-core) returns empty in Z3

Question

I am using Z3 to extract the unsat-core of an unsatisfiable formula. I am using Z3@Rise interface (web based) to write the following code,

(set-logic QF_LIA)         


        

Answer 1

You need to add name labels to your assertions so get-unsat-core has labels to use in the unsat core output. Write your assertions like this:

(assert (! one :named a1))
(assert (! two :named a2))
(assert (! three :named a3))
(assert (! four :named a4))
(assert (! five :named a5))
(assert (! six :named a6))
(assert (! secondpartA :named spA))
(assert (! secondpartB :named spB))

and get-unsat-core will print an unsat core.

Documentation for this syntax can be found in the SMTLIB tutorial (PDF file).