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/******************************************************************************
* Top contributors (to current version):
* Pat Hawks, Andres Noetzli
*
* 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.
* ****************************************************************************
*
* [[ Add one-line brief description here ]]
*
* [[ Add lengthier description here ]]
* \todo document this file
*/
import static org.junit.Assert.assertEquals;
import edu.stanford.CVC4.*;
import org.junit.Before;
import org.junit.Test;
public class LinearArith {
static {
System.loadLibrary("cvc4jni");
}
ExprManager em;
SmtEngine smt;
@Before
public void initialize() {
em = new ExprManager();
smt = new SmtEngine(em);
}
@Test
public void evaluatesExpression() {
smt.setLogic("QF_LIRA"); // Set the logic
// Prove that if given x (Integer) and y (Real) then
// the maximum value of y - x is 2/3
// Types
Type real = em.realType();
Type integer = em.integerType();
// Variables
Expr x = em.mkVar("x", integer);
Expr y = em.mkVar("y", real);
// Constants
Expr three = em.mkConst(new Rational(3));
Expr neg2 = em.mkConst(new Rational(-2));
Expr two_thirds = em.mkConst(new Rational(2,3));
// Terms
Expr three_y = em.mkExpr(Kind.MULT, three, y);
Expr diff = em.mkExpr(Kind.MINUS, y, x);
// Formulas
Expr x_geq_3y = em.mkExpr(Kind.GEQ, x, three_y);
Expr x_leq_y = em.mkExpr(Kind.LEQ, x, y);
Expr neg2_lt_x = em.mkExpr(Kind.LT, neg2, x);
Expr assumptions =
em.mkExpr(Kind.AND, x_geq_3y, x_leq_y, neg2_lt_x);
smt.assertFormula(assumptions);
smt.push();
Expr diff_leq_two_thirds = em.mkExpr(Kind.LEQ, diff, two_thirds);
assertEquals(Result.Entailment.ENTAILED,
smt.checkEntailed(diff_leq_two_thirds).isEntailed());
smt.pop();
smt.push();
Expr diff_is_two_thirds = em.mkExpr(Kind.EQUAL, diff, two_thirds);
smt.assertFormula(diff_is_two_thirds);
assertEquals(
Result.Sat.SAT,
smt.checkSat(em.mkConst(true)).isSat()
);
smt.pop();
}
}
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