almazis / aeval

AE-solver and Skolemizer

About

A functional synthesis tool based on the Z3 SMT solver. It expects single-invocation specifications over linear integer/real arithmetic, encoded as forall-exists formulas, and aims at generating witnessing Skolem functions for (possibly, many) existentially-quantified variables. See the VMCAI'19 paper for more details.

Installation

Compiles with gcc-7 (on Linux) and clang-900 (on Mac). Assumes preinstalled Gmp (with the --enable-cxx flag) and Boost 1.71 packages.

• cd aeval ; mkdir build ; cd build
• cmake ../
• make to build dependencies (i.e., it needs a particular version of Z3 and installs it automatically)
• make to build AE-VAL

The binary of AE-VAL can be found in build/tools/aeval/.

Usage

The tool takes as input formulas in SMT-LIB v2, e.g., the following specification for the max function:

(assert (forall ((x1 Int) (x2 Int))
    (exists ((y Int))
        (and (>= y x1) (>= y x2) (or (= y x1) (= y x2))))))

Running aeval --skol max.smt2 yields the realizability result valid and the extracted Skolem for the y variable:

Iter: 2; Result: valid
(define-fun y ((x1 Int)(x2 Int)) Int
    (ite (<= (+ x1 (- x2)) 0) x2 x1))