hexhex / core

DLVHEX solver: core system and plugin API
http://www.kr.tuwien.ac.at/research/systems/dlvhex/
GNU Lesser General Public License v2.1
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DLV safety #2

Open credl opened 12 years ago

credl commented 12 years ago

The following program is rejected by DLV because the rule is not safe:

p(a). q(Y) :- p(X), X=Y.

In DLV, =/2 is considered as a comparison predicate (such as <, >, etc.) which expects both terms to be safe.

However, it is clear that the program can be grounded without any troubles (e.g. by gringo and the internal grounder).

dlvhex shall adopt the latter point of view, but currently this does not work with DLV backend. A possible fix is a rewriting.