Add quantifiers API example, fixes #879 (#1146)

diff --git a/examples/simple_vc_quant_cxx.cpp b/examples/simple_vc_quant_cxx.cpp
new file mode 100644 (file)
index 0000000..299918e
--- /dev/null
+++ b/examples/simple_vc_quant_cxx.cpp
@@ -0,0 +1,78 @@
+/*********************                                                        */
+/*! \file simple_vc_quant_cxx.cpp
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2017 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 C++ interface for quantifiers
+ **
+ ** A simple demonstration of the C++ interface for quantifiers. 
+ **/
+
+#include <iostream>
+
+//#include <cvc4/cvc4.h> // use this after CVC4 is properly installed
+#include "smt/smt_engine.h"
+
+using namespace std;
+using namespace CVC4;
+
+int main() {
+  ExprManager em;
+  SmtEngine smt(&em);
+
+  // Prove that the following is unsatisfiable:
+  //   forall x. P( x ) ^ ~P( 5 )
+
+  Type integer = em.integerType();
+  Type boolean = em.booleanType();
+  Type integerPredicate = em.mkFunctionType(integer, boolean);
+  
+  Expr p = em.mkVar("P", integerPredicate);
+  Expr x = em.mkBoundVar("x", integer);
+  
+  // make forall x. P( x )
+  Expr var_list = em.mkExpr(kind::BOUND_VAR_LIST, x);
+  Expr px = em.mkExpr(kind::APPLY_UF, p, x);
+  Expr quantpospx = em.mkExpr(kind::FORALL, var_list, px);
+  cout << "Made expression : " << quantpospx << endl;
+  
+  //make ~P( 5 )
+  Expr five = em.mkConst(Rational(5));
+  Expr pfive = em.mkExpr(kind::APPLY_UF, p, five);
+  Expr negpfive = em.mkExpr(kind::NOT, pfive);
+  cout << "Made expression : " << negpfive << endl;
+  
+  Expr formula = em.mkExpr(kind::AND, quantpospx, negpfive);
+
+  smt.assertFormula(formula);
+
+  cout << "Checking SAT after asserting " << formula << " to CVC4." << endl;
+  cout << "CVC4 should report unsat." << endl;
+  cout << "Result from CVC4 is: " << smt.checkSat() << endl;
+
+
+  SmtEngine smtp(&em);
+  
+  // this version has a pattern e.g. in smt2 syntax (forall ((x Int)) (! (P x ) :pattern ((P x))))
+  Expr pattern = em.mkExpr(kind::INST_PATTERN, px);
+  Expr pattern_list = em.mkExpr(kind::INST_PATTERN_LIST, pattern);
+  Expr quantpospx_pattern = em.mkExpr(kind::FORALL, var_list, px, pattern_list);
+  cout << "Made expression : " << quantpospx_pattern << endl;
+
+  Expr formula_pattern = em.mkExpr(kind::AND, quantpospx_pattern, negpfive);
+
+  smtp.assertFormula(formula_pattern);
+
+  cout << "Checking SAT after asserting " << formula_pattern << " to CVC4." << endl;
+  cout << "CVC4 should report unsat." << endl;
+  cout << "Result from CVC4 is: " << smtp.checkSat() << endl;
+
+
+  return 0;
+}