Unexplained behaviour wrt the well founded semantics - Part 4

Help!
3

The most sensible definitions I can come up with are

isUndefined(Atom) :- call_delays(Atom, Delays), Delays \== true.
isTrue(Atom)      :- call_delays(Atom, true).
isFalse(Atom)     :- \+ isTrue(Atom).

That works fairly well, except that isFalse/1 requires a ground argument to avoid floundering. You need constructive negation. sCASP can do that. Still learning, I tried. sCASP on

q(1).
r(3).

p(X) :- r(X), not p(X).
p(X) :- q(X).

gives “no models” on every query though because our knowledge base is inconsistent. If we delete the inconsistent first clause for p/1 we get

?- not p(X).

MODEL:
{ not q(X | {X \= 1}),  not p(X | {X \= 1}) }

BINDINGS: 
X \= 1 ?

Trying to get my head around the advantages and disadvantages of WFS, ASP and sCASP …

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