(adsbygoogle = window.adsbygoogle || []).push({}); How can we prove that "P V Q" is not a Horn Clause

Does anyone have an idea how to prove that "P V Q" is not equivalent to any horn formula. All I seem to find is people saying that it is a very clear counter-example, but I need more of a formal method of proof.

Any ideas?

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# P V Q is not a Horn Clause

**Physics Forums | Science Articles, Homework Help, Discussion**