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/********************* */
/*! \file sygus-inv.cpp
** \verbatim
** Top contributors (to current version):
** Abdalrhman Mohamed
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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.\endverbatim
**
** \brief 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 to this example should be equivalent to:
** (define-fun inv-f ((x Int)) Bool (not (>= x 11)))
**/
#include <cvc4/api/cvc4cpp.h>
#include <iostream>
using namespace CVC4::api;
int main()
{
Solver slv;
// required options
slv.setOption("lang", "sygus2");
slv.setOption("incremental", "false");
// set the logic
slv.setLogic("LIA");
Sort integer = slv.getIntegerSort();
Sort boolean = slv.getBooleanSort();
Term zero = slv.mkReal(0);
Term one = slv.mkReal(1);
Term ten = slv.mkReal(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", {x}, boolean, slv.mkTerm(EQUAL, x, zero));
Term trans_f = slv.defineFun("trans-f", {x, xp}, boolean, ite);
Term post_f = slv.defineFun("post-f", {x}, boolean, slv.mkTerm(LEQ, x, ten));
// declare the invariant-to-synthesize
Term inv_f = slv.synthInv("inv-f", {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)))
slv.printSynthSolution(std::cout);
}
return 0;
}
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