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/********************* */
/*! \file Combination.java
** \verbatim
** Top contributors (to current version):
** Morgan Deters, Tim King, Aina Niemetz
** 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 capabilities of CVC4
**
** A simple demonstration of how to use uninterpreted functions, combining this
** with arithmetic, and extracting a model at the end of a satisfiable query.
** The model is displayed using getValue().
**/
import edu.stanford.CVC4.*;
public class Combination {
private static void prefixPrintGetValue(SmtEngine smt, Expr e, int level) {
for(int i = 0; i < level; ++i) { System.out.print('-'); }
System.out.println("smt.getValue(" + e + ") -> " + smt.getValue(e));
if(e.hasOperator()) {
prefixPrintGetValue(smt, e.getOperator(), level + 1);
}
for(int i = 0; i < e.getNumChildren(); ++i) {
Expr curr = e.getChild(i);
prefixPrintGetValue(smt, curr, level + 1);
}
}
public static void main(String[] args) {
System.loadLibrary("cvc4jni");
ExprManager em = new ExprManager();
SmtEngine smt = new SmtEngine(em);
smt.setOption("tlimit", new SExpr(100));
smt.setOption("produce-models", new SExpr(true)); // Produce Models
smt.setOption("output-language", new SExpr("cvc4")); // output-language
smt.setOption("dag-thresh", new SExpr(0)); //Disable dagifying the output
smt.setLogic("QF_UFLIRA");
// Sorts
SortType u = em.mkSort("u");
Type integer = em.integerType();
Type booleanType = em.booleanType();
Type uToInt = em.mkFunctionType(u, integer);
Type intPred = em.mkFunctionType(integer, booleanType);
// Variables
Expr x = em.mkVar("x", u);
Expr y = em.mkVar("y", u);
// Functions
Expr f = em.mkVar("f", uToInt);
Expr p = em.mkVar("p", intPred);
// Constants
Expr zero = em.mkConst(new Rational(0));
Expr one = em.mkConst(new Rational(1));
// Terms
Expr f_x = em.mkExpr(Kind.APPLY_UF, f, x);
Expr f_y = em.mkExpr(Kind.APPLY_UF, f, y);
Expr sum = em.mkExpr(Kind.PLUS, f_x, f_y);
Expr p_0 = em.mkExpr(Kind.APPLY_UF, p, zero);
Expr p_f_y = em.mkExpr(Kind.APPLY_UF, p, f_y);
// Construct the assumptions
Expr assumptions =
em.mkExpr(Kind.AND,
em.mkExpr(Kind.LEQ, zero, f_x), // 0 <= f(x)
em.mkExpr(Kind.LEQ, zero, f_y), // 0 <= f(y)
em.mkExpr(Kind.LEQ, sum, one), // f(x) + f(y) <= 1
p_0.notExpr(), // not p(0)
p_f_y); // p(f(y))
smt.assertFormula(assumptions);
System.out.println("Given the following assumptions:");
System.out.println(assumptions);
System.out.println("Prove x /= y is entailed. "
+ "CVC4 says: " + smt.checkEntailed(em.mkExpr(Kind.DISTINCT, x, y))
+ ".");
System.out.println("Now we call checksat on a trivial query to show that");
System.out.println("the assumptions are satisfiable: " +
smt.checkSat(em.mkConst(true)) + ".");
System.out.println("Finally, after a SAT call, we recursively call smt.getValue(...) on " +
"all of the assumptions to see what the satisfying model looks like.");
prefixPrintGetValue(smt, assumptions, 0);
}
}
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