Problem 7.2

Master / Vertiefung Künstliche Intelligenz
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2

Problem 7.2
Hey, for me it seems like that the fixity parameters in the definitions of the connectives are not correct, as the example here shows:

test(X>Y):- writeln(X), writeln(Y).

?- test(a>b>c>d).
a>b>c
d
true.

I think that when matching [m]a>b>c>d[/m] with [m]X>Y[/m], [m]X[/m] should be [m]a[/m] ?

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Nope, implication is left-associative (yfx), i.e. a>b>c>d is parsed as (((a>b)>c)>d), which means prolog pattern-matches correctly :wink:

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ah, wait, but it should be right-associative… sorry, I always get confused. Which is why I strongly prefer to just use brackets when dealing with non-associative connectives.

Yes, you can fix that (apparently) by using xfy instead of yfx.