/// <summary>
/// Checks, that passed nodes can be unificated
/// </summary>
/// <param name="node1"></param>
/// <param name="node2"></param>
/// <returns></returns>
public static bool CanUnificate(SkolemPredicateNode node1, SkolemPredicateNode node2)
{
// The predicate name is unique
if (!node1.Name.Equals(node2.Name))
{
return(false);
}
return(GetUnificationRules(node1, node2) != null);
}
public void UnificationTest()
{
// P(f(x), z)
var A = new SkolemPredicateNode("P", false, new FunctionNode("f", VariableNode.Make <bool>(0, "x")),
VariableNode.Make <bool>(2, "z"));
// P(y,a)
var B = new SkolemPredicateNode("P", false, VariableNode.Make <bool>(1, "y"), new FunctionNode("a"));
Assert.AreEqual(true, UnificationService.CanUnificate(A, B));
var rules = UnificationService.GetUnificationRules(A, B);
Assert.AreEqual(2, rules.Count);
UnificationService.Unificate(A, rules);
UnificationService.Unificate(B, rules);
Assert.AreEqual("P(f(x),a)", A.ToString());
Assert.AreEqual(A.ToString(), B.ToString());
}
public void ComplexUnificationTest()
{
// !P(x,b,z,s) V ANS(f(g(z,b,h(x,z,s))))
var A = new MultipleOr(
new SkolemPredicateNode("P", true, VariableNode.Make <bool>(0, "x"), new FunctionNode("b"), VariableNode.Make <bool>(2, "z"), VariableNode.Make <bool>(3, "s")),
new SkolemPredicateNode("ANS", false,
new FunctionNode("f",
new FunctionNode("g", VariableNode.Make <bool>(2, "z"), new FunctionNode("b"),
new FunctionNode("h", VariableNode.Make <bool>(0, "x"), VariableNode.Make <bool>(2, "z"), VariableNode.Make <bool>(3, "s"))))));
// P(a,b,c,s0)
var B = new SkolemPredicateNode("P", false, new FunctionNode("a"), new FunctionNode("b"), new FunctionNode("c"), new FunctionNode("s0"));
Assert.AreEqual(true, UnificationService.CanUnificate((SkolemPredicateNode)A.Children[0], B));
var rules = UnificationService.GetUnificationRules((SkolemPredicateNode)A.Children[0], B);
Assert.AreEqual(3, rules.Count);
UnificationService.Unificate(A, rules);
Assert.AreEqual("!P(a,b,c,s0) ∨ ANS(f(g(c,b,h(a,c,s0))))", A.ToString());
}