cvc5/examples/api/java/SygusInv.java

/******************************************************************************
 * Top contributors (to current version):
 *   Abdalrhman Mohamed, Mudathir Mohamed, Aina Niemetz
 *
 * This file is part of the cvc5 project.
 *
 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 * in the top-level source directory and their institutional affiliations.
 * All rights reserved.  See the file COPYING in the top-level source
 * directory for licensing information.
 * ****************************************************************************
 *
 * A simple demonstration of the Sygus API.
 *
 * A simple demonstration of how to use the Sygus API to synthesize a simple
 * invariant. Here is the same problem written in Sygus V2 format:
 *
 * (set-logic LIA)
 *
 * (synth-inv inv-f ((x Int)))
 *
 * (define-fun pre-f ((x Int)) Bool
 *   (= x 0))
 * (define-fun trans-f ((x Int) (xp Int)) Bool
 *   (ite (< x 10) (= xp (+ x 1)) (= xp x)))
 * (define-fun post-f ((x Int)) Bool
 *   (<= x 10))
 *
 * (inv-constraint inv-f pre-f trans-f post-f)
 *
 * (check-synth)
 *
 * The printed output for this example should be equivalent to:
 * (
 *   (define-fun inv-f ((x Int)) Bool (not (>= x 11)))
 * )
 */

import static io.github.cvc5.api.Kind.*;

import io.github.cvc5.api.*;

public class SygusInv
{
  public static void main(String args[]) throws CVC5ApiException
  {
    Solver slv = new Solver();

    // required options
    slv.setOption("lang", "sygus2");
    slv.setOption("incremental", "false");

    // set the logic
    slv.setLogic("LIA");

    Sort integer = slv.getIntegerSort();
    Sort bool = slv.getBooleanSort();

    Term zero = slv.mkInteger(0);
    Term one = slv.mkInteger(1);
    Term ten = slv.mkInteger(10);

    // declare input variables for functions
    Term x = slv.mkVar(integer, "x");
    Term xp = slv.mkVar(integer, "xp");

    // (ite (< x 10) (= xp (+ x 1)) (= xp x))
    Term ite = slv.mkTerm(ITE,
        slv.mkTerm(LT, x, ten),
        slv.mkTerm(EQUAL, xp, slv.mkTerm(PLUS, x, one)),
        slv.mkTerm(EQUAL, xp, x));

    // define the pre-conditions, transition relations, and post-conditions
    Term pre_f = slv.defineFun("pre-f", new Term[] {x}, bool, slv.mkTerm(EQUAL, x, zero));
    Term trans_f = slv.defineFun("trans-f", new Term[] {x, xp}, bool, ite);
    Term post_f = slv.defineFun("post-f", new Term[] {x}, bool, slv.mkTerm(LEQ, x, ten));

    // declare the invariant-to-synthesize
    Term inv_f = slv.synthInv("inv-f", new Term[] {x});

    slv.addSygusInvConstraint(inv_f, pre_f, trans_f, post_f);

    // print solutions if available
    if (slv.checkSynth().isUnsat())
    {
      // Output should be equivalent to:
      // (
      //   (define-fun inv-f ((x Int)) Bool (not (>= x 11)))
      // )
      Term[] terms = new Term[] {inv_f};
      Utils.printSynthSolutions(terms, slv.getSynthSolutions(terms));
    }
  }
}