How to implement AND / OR logic

[Young Park]

I am a newbee in PyKE, went over the tutorial, installed, ran examples.
Now I am writing rulebase of my own, and encountered a missing hole.

Suppose that I made a fact base consisting of simple facts.
Then made rulebase of FC and BC rules composing from the elementary facts.
How can i make rules of AND and OR conditions?
For example, (A and B) or C or (D and E) in Prolog would be something like this:
P :- (A, B); C; (D, E)

I would appreciate much for such initial help.

• Young Park

[Bruce Frederiksen]

Facts are AND-ed be default in Pyke when you list more than one of them in a rule.

Pyke does not have OR-ing within a rule.  Instead, you would use multiple rules.  Using your Prolog example:

P :- A, B.
P :- C.
P :- D, E.

or, in Pyke:

rule1
    use P( )
    when
        A( )
        B( )
rule2
    use P( )
    when
        C( )
rule3
    use P( )
    when
        D( )
        E( )

-Bruce

[Young Park]

Thank you Bruce.
Then how to implement rules like the following?
P :- A, (B; C), (D; E).
i.e. A and (B or C) and (D or E).

Thank you in advance for your help.

• Young Park

[Bruce Frederiksen]

You can do this by creating subgoals:

P :- A, P2, P3.
P2 :- B.
P2 :- C.
P3 :- D.
P3 :- E.

-Bruce

[Angle]

You can, actually, make OR rules, though it's kind of a hack:

if_C_or_D_then_F
    foreach
        $facts = ('C', 'D')
        python satisfied = False;
        forall
            $fact in $facts
            test.fact($fact)
            python satisfied = True;
        check satisfied is True
    assert
        test.fact(F)