examples/simple_vc_cxx.cpp

   1 /*********************                                                        */
   2 /*! \file simple_vc_cxx.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Morgan Deters, Dejan Jovanovic
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
   8  ** in the top-level source directory) and their institutional affiliations.
   9  ** All rights reserved.  See the file COPYING in the top-level source
  10  ** directory for licensing information.\endverbatim
  11  **
  12  ** \brief A simple demonstration of the C++ interface
  13  **
  14  ** A simple demonstration of the C++ interface.  Compare to the Java
  15  ** interface in SimpleVC.java; they are virtually line-by-line
  16  ** identical.
  17  **/
  18
  19 #include <iostream>
  20
  21 #include <cvc4/cvc4.h>
  22
  23 using namespace std;
  24 using namespace CVC4;
  25
  26 int main() {
  27   ExprManager em;
  28   SmtEngine smt(&em);
  29
  30   // Prove that for integers x and y:
  31   //   x > 0 AND y > 0  =>  2x + y >= 3
  32
  33   Type integer = em.integerType();
  34
  35   Expr x = em.mkVar("x", integer);
  36   Expr y = em.mkVar("y", integer);
  37   Expr zero = em.mkConst(Rational(0));
  38
  39   Expr x_positive = em.mkExpr(kind::GT, x, zero);
  40   Expr y_positive = em.mkExpr(kind::GT, y, zero);
  41
  42   Expr two = em.mkConst(Rational(2));
  43   Expr twox = em.mkExpr(kind::MULT, two, x);
  44   Expr twox_plus_y = em.mkExpr(kind::PLUS, twox, y);
  45
  46   Expr three = em.mkConst(Rational(3));
  47   Expr twox_plus_y_geq_3 = em.mkExpr(kind::GEQ, twox_plus_y, three);
  48
  49   Expr formula =
  50     em.mkExpr(kind::AND, x_positive, y_positive).
  51     impExpr(twox_plus_y_geq_3);
  52
  53   cout << "Checking entailment of formula " << formula << " with CVC4." << endl;
  54   cout << "CVC4 should report ENTAILED." << endl;
  55   cout << "Result from CVC4 is: " << smt.checkEntailed(formula) << endl;
  56
  57   return 0;
  58 }