public SubstitutionSet Unify(IUnifiable p,
SubstitutionSet s)
{
if (p is SimpleSentence)
{
SimpleSentence s1 = (SimpleSentence)p;
if (terms.Length != s1.terms.Length)
{
return(null);
}
SubstitutionSet sNew = new SubstitutionSet(s);
for (int i = 0; i < terms.Length; i++)
{
sNew = terms[i].Unify(s1.terms[i], sNew);
if (sNew == null)
{
return(null);
}
}
return(sNew);
}
if (p is Variable)
{
return(p.Unify(this, s));
}
return(null);
}
private void UnifyTester()
{
Constant friend = new Constant("friend");
Constant bill = new Constant("bill");
Constant george = new Constant("george");
Constant kate = new Constant("kate");
Constant merry = new Constant("merry");
Variable X = new Variable("X");
Variable Y = new Variable("Y");
List <IUnifiable> expressions = new List <IUnifiable>();
IUnifiable[] terms = new IUnifiable[2];
terms[0] = bill;
terms[1] = george;
expressions.Add(new SimpleSentence(friend, terms));
terms[1] = kate;
expressions.Add(new SimpleSentence(friend, terms));
terms[1] = merry;
expressions.Add(new SimpleSentence(friend, terms));
terms[0] = george;
terms[1] = bill;
expressions.Add(new SimpleSentence(friend, terms));
terms[1] = kate;
expressions.Add(new SimpleSentence(friend, terms));
terms[0] = kate;
terms[1] = merry;
expressions.Add(new SimpleSentence(friend, terms));
terms[0] = X;
terms[1] = Y;
IUnifiable goal = new SimpleSentence(friend, terms);
SubstitutionSet s = null;
textBox1.Text += "Goal: " + goal.ToString() + "\r\n";
for (int i = 0; i < expressions.Count; i++)
{
IUnifiable next = expressions[i];
s = next.Unify(goal, new SubstitutionSet());
textBox1.Text += next.ToString() + "\t";
if (s != null)
{
IPCExpression ipcexp = goal.ReplaceVariables(s);
SimpleSentence sent = (SimpleSentence)ipcexp;
textBox1.Text += sent.ToString() + "\r\n";
}
else
{
textBox1.Text += "False\r\n";
}
}
terms[0] = bill;
terms[1] = Y;
goal = new SimpleSentence(friend, terms);
textBox1.Text += "Goal: " + goal.ToString() + "\r\n";
for (int i = 0; i < expressions.Count; i++)
{
IUnifiable next = expressions[i];
s = next.Unify(goal, new SubstitutionSet());
textBox1.Text += next.ToString() + "\t";
if (s != null)
{
IPCExpression ipcexp = goal.ReplaceVariables(s);
textBox1.Text += ipcexp.ToString() + "\r\n";
}
else
{
textBox1.Text += "False\r\n";
}
}
}