Recursion detection is too strict

[stephanzwicknagl]

• The recursion detection has to be improved, because it can wrongly detect recursion sometimes

Example:

in(E,alle) :- map(_,_,S), in(SS,S), in(E,SS), I=1..n.
{ in(E,e(I)) } :- in(E,alle), I=1..n.
in(E,be(I..n)) :- in(E,e(I)).
in(E,e) :- in(E,e(I)).

This set of rules will be grouped into a recursive component, because the rules have the literal in/2 in their body.

However, the ground rules they generate are very different. Rule 1 has dependant in with alle, rule 2 has dependant in with e(I), rule 3 has dependant in with be(I), rule 4 has dependant in with e. This means that the predicates are not really recursively generated.

Renaming the predicates shows this:

in0(E,alle) :- map(_,_,S), in(SS,S), in(E,SS), I=1..n.
{ in1(E,e(I)) } :- in0(E,alle), I=1..n.
E,be(I..n)) :- in1(E,e(I)).
in3(E,e) :- in1(E,e(I)).