/// <summary>
/// Using resolution rule: A V B, C V !B |- A V C.
/// </summary>
/// <param name="z"></param>
private static void Modificator(ITypizedDecorArray <MultipleOr, SkolemPredicateNode, MultipleOr, SkolemPredicateNode> z)
{
var rules = UnificationService.GetUnificationRules(z.B.Node, z.D.Node);
UnificationService.Unificate(z.A.Node, rules);
UnificationService.Unificate(z.C.Node, rules);
var aChildren = z.A.Node.Children.ToList();
var cChildren = z.C.Node.Children.ToList();
aChildren.Remove(z.B.Node);
cChildren.Remove(z.D.Node);
z.A.Replace(new MultipleOr(aChildren.ToArray()));
z.C.Replace(new MultipleOr(cChildren.ToArray()));
}
public void HardUnificationTest()
{
// P(a,x,f(g(y))
Expression <Del2> A = (x, y) => P(a, x, f(g(y)));
// P(z,f(z),f(u))
Expression <Del2> B = (z, u) => P(z, f(z), f(u));
var node1 = (SkolemPredicateNode)Expressions2LogicTree.Parse(A).Children[0];
var node2 = (SkolemPredicateNode)Expressions2LogicTree.Parse(B).Children[0];
Assert.AreEqual(true, UnificationService.CanUnificate(node1, node2));
var rules = UnificationService.GetUnificationRules(node1, node2);
Assert.AreEqual(3, rules.Count);
UnificationService.Unificate(node1, node2);
Assert.AreEqual(node1.ToString(), node2.ToString());
}
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());
}