I'm working through my AI textbook I got and I've come to the last homework problem for my section:
"Implement the Unification Algorithm outlined on page 69 in any language of your choice."
On page 69, you have the following pseudo-code for the unification algorithm:
function unify(E1, E2);
begin
case
both E1 and E2 are constants or the empty list:
if E1 = E2 then return {}
else return FAIL;
E1 is a variable:
if E1 occurs in E2 then return FAIL
else return {E2/E1}
E2 is a variable
if E2 occurs in E1 then FAIL
else return {E1/E2}
either E1 or E2 are empty then return FAIL
otherwise:
begin
HE1 := first element of E1;
HE2 := first element of E2;
SUBS1 := unify(HE1, HE2);
if SUBS1 := FAIL then return FAIL;
TE1 := apply(SUBS1, rest of E1);
TE2 := apply(SUBS1, rest of E2);
SUBS2 := unify(TE1, TE2);
if SUBS2 = FAIL then return FAIL;
else return composition(SUBS1, SUBS2)
end
end
end
Now, I understand the general concept of unification but I have absolutely no idea how I would even begin to implement this in a language like Java or C#.
I'm not even sure what the method signature would look like. What type of variables would it take? I'm fairly certain I need to return lists to represent predicate calculus constructs but that is a guess.
For example, when it says "E1 is a variable", well, if I'm passing it into the Unify method, how could it be anything but? I could check for null but would that be different than "empty list"?
Can anyone help me or point me in the right direction for implementing the Unificaiton algorithm in C# or Java?