=>, is this "forward chaining"


I am still trying to understand the new =>/2 operator.

Is this essentially, a simple forward chaining mechanism – how does backtracking intended to work with this.


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How would it be forward chaining? It is just a Prolog clause with single sided unification and an implicit commit (cut). The search for rules is the same, only the matching differs. The simplest answer to forward chaining is tabling :slight_smile:

Thank you.

Yes, no “chaining” here, just some kind of “forward” …

I don’t know why i am blanking on this new construct to graps it.

Perhaps, if you can explain why its called “single sided unification” what is single sided vs. multi-sided about this, and what is multi-sided …

Is side, the side of the operator “=>” or “:-” …


Could you provide at least some explanation of or examples to the statement: the simplest answer to forward chaining is tabling?

Would still be interesting to know how tabling enables forward chaining – if you have some thoughts on that, that would be great.

Tabling could indeed be considered as an answer to forward chaining. Roughly, tabling performs backward chaining while identifying recursive calls that call the same variant goal. Such goals and delayed. The subsequent tabling completion phase identifies the delayed goals and performs forward chaining on them until fixed point is reached.


Jan, what is a same and a variant goal … could you provide an example … can these calls be traced … to see (and learn) what happens in practice.


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Did you read:




Thank you – indeed its there …