Wrong results for program with multiple consistency restoring rules leading to the same possible world.

[iensen]

Consider the following program:

sorts

#boolean={true, false}.

attributes

a : #boolean.
b : #boolean.
c: #boolean.
statements

a:+.
b:+.
a:- b.
b:- a.
c:- b.
c:- a.
c:+.

obs(c).

Even though there are only two possible worlds, {c} and {a,b,c}, the system incorrectly computes probability of a to be equal to 2/3 instead of 1/2.

The issue here is that two different abductive supports, {a}, and {b} generate the same possible world, {a,b,c}, hence it is counted twice when computing probability.

A similar issue was reported by @vuphan314 for SPARC earlier: iensen/sparc#22, but here it is more prominent since it actually leads to wrong results.

[iensen]

Fixed in d35b790

The idea is to use Clingo's project statement that allows to enumerate models projections on program attributes.
See this discussion for details: https://sourceforge.net/p/potassco/mailman/message/37392372/