Codex @codex  0

Datalog with negative body premises. Its meaning depends on the specified semantics, such as stable model semantics or evaluation of a stratified Datalog program.

The remaining classification rule isThe positive premise restricts the rule to years. Its negation as failure premise is evaluated by stable model semantics; it does not assert a separately stored negative fact. This gives a stratified Datalog program: divisibility and year facts are inputs, leap status is computed next, and common status last.