Re: NULLs: theoretical problems?

>> As a matter of fact, there are a few competing definitions to choose from, Lukaciewicz's, Kleene's and someone else's whose name I do not recall. <<

You are probably thinking of Post, but there is more than that. "Many-  Logics- Volume 1: Theoretical Foundations" by Bolc and Borowik, 1992, ISBN 978-3-540-55926-9 is filled with 2-3 page explanations of a ton of such systems. Received on Sat Aug 11 2007 - 13:57:12 CDT