I am confused with the OR logic.

[jyt13]

Below is the conditions I defined known(a) :- known(b), known(c). known(b) :- known(d); known(e). If b and c is known then a is known; If d or e is known then b is known. I hope like if I give two facts, d is known and c is known, the platform can deduce that a is known. However it does not work, and as I test, the OR logic here seems not working as expected.

And the following codes work: known(a) :- known(b), known(c). known(b) :- {known(d); known(e)}>=1. I used a more direct approach, and that's right. with 2 facts known(c). known(d). It can be solved that finally a,b,c and d are known.

I am using clingo 4.5.4

Thank you in advance

[rkaminsk]

The ; separator is not a disjunction but can alternatively be used to separate body elements. To express disjunction with normal rules, you can use

known(b) :- known(d).
known(b) :- known(e).

For the example above, you could also use

known(b) :- known(d;e).

Have a look at https://arxiv.org/abs/1507.06576 for a precise semantics.

[jyt13]

The ; separator is not a disjunction but can alternatively be used to separate body elements. To express disjunction with normal rules, you can use

known(b) :- known(d).
known(b) :- known(e).

For the example above, you could also use

known(b) :- known(d;e).

Have a look at https://arxiv.org/abs/1507.06576 for a precise semantics.

Thank you so much.