static void fOL_Demodulation()
{
System.Console.WriteLine("-----------------");
System.Console.WriteLine("Demodulation Demo");
System.Console.WriteLine("-----------------");
FOLDomain domain = new FOLDomain();
domain.addConstant("A");
domain.addConstant("B");
domain.addConstant("C");
domain.addConstant("D");
domain.addConstant("E");
domain.addPredicate("P");
domain.addFunction("F");
domain.addFunction("G");
domain.addFunction("H");
domain.addFunction("J");
FOLParser parser = new FOLParser(domain);
Predicate expression = (Predicate)parser.parse("P(A,F(B,G(A,H(B)),C),D)");
TermEquality assertion = (TermEquality)parser.parse("B = E");
Demodulation demodulation = new Demodulation();
Predicate altExpression = (Predicate)demodulation.apply(assertion, expression);
System.Console.WriteLine("Demodulate '" + expression + "' with '" + assertion + "' to give");
System.Console.WriteLine(altExpression.ToString());
System.Console.WriteLine("and again to give");
System.Console.WriteLine(demodulation.apply(assertion, altExpression).ToString());
System.Console.WriteLine("");
}
public void testSimpleAtomicExamples()
{
FOLDomain domain = new FOLDomain();
domain.addConstant("A");
domain.addConstant("B");
domain.addConstant("C");
domain.addConstant("D");
domain.addConstant("E");
domain.addPredicate("P");
domain.addFunction("F");
domain.addFunction("G");
domain.addFunction("H");
domain.addFunction("J");
FOLParser parser = new FOLParser(domain);
Predicate expression = (Predicate)parser
.parse("P(A,F(B,G(A,H(B)),C),D)");
TermEquality assertion = (TermEquality)parser.parse("B = E");
Predicate altExpression = (Predicate)demodulation.apply(assertion,
expression);
Assert.IsFalse(expression.Equals(altExpression));
Assert
.AreEqual("P(A,F(E,G(A,H(B)),C),D)", altExpression
.ToString());
altExpression = (Predicate)demodulation
.apply(assertion, altExpression);
Assert
.AreEqual("P(A,F(E,G(A,H(E)),C),D)", altExpression
.ToString());
assertion = (TermEquality)parser.parse("G(x,y) = J(x)");
altExpression = (Predicate)demodulation.apply(assertion, expression);
Assert.AreEqual("P(A,F(B,J(A),C),D)", altExpression.ToString());
}
public Clause simplify(Clause c)
{
Clause simplified = c;
// Apply each of the rewrite rules to the clause
foreach (TermEquality te in rewrites)
{
Clause dc = simplified;
// Keep applying the rewrite as many times as it
// can be applied before moving on to the next one.
while (null != (dc = demodulation.apply(te, dc)))
{
simplified = dc;
}
}
return(simplified);
}
