(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?

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

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# P V Q is not a Horn Clause

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