Prolog Questions

[slavano]

I am currently tying to work on a Prolog example from a course that has something like the fallowing

 

start(state(e, e, e, e)).

rule( (move(state(F1, W1, G1, C1), Ed) :- (start(state(F1, W1, G1, C1)), otherRandomPredicates(Ed....) ) ), 100)

 

The predicate is a bit confusing and a bit vague but my question is, when I run using SWI-Prolog (or even GNU Prolog for that matter), the variables F1, W1, G1 and C1 aren't assigned the value of e, e, e and e as would happen if I just ran

 

start(state(F1, W1, G1, C1)).

 

outside of the "rule" predicate.

 

Does anyone know why this is?

[Sauron]

I don't know much about prolog, but are you sure you can assign the same name to 4 different values? (e)

[slavano]

2 minutes ago, Sauron said:

I don't know much about prolog, but are you sure you can assign the same name to 4 different values? (e)

In Prolog, Variables start with capitals and atoms/predicates start with lower case. So yes, the 4 variables can all have the save value of 'e'.

[elpiop]

My guess is that the unification is failing because although, yes, you can unify the variables in (start(state(F1, W1, G1, C1)) with start(state(e, e, e, e)), the unification fails for  rule((move(state(F1, W1, G1, C1)... Since there is no satisfying assignment for the variables in BOTH terms