1. Re: 'Unknown' and three-valued logic
- Posted by Juergen Luethje <jluethje at gmx.de> Nov 24, 2002
- 383 views
Pete wrote: >> Unknown xor Unknown can be True or False dm31 at uow.edu.au wrote: > Hence, Unknown, since we are not sure which. :P You are right! In my truth table, I had written that Unknown xor Unknown = False. That was not correct. I checked it using the following formula: a xor b = (a and (not b)) or ((not a) and b) <http://mathworld.wolfram.com/XOR.html> Using "U" for "Unknown", the formula gives: U xor U = (U and (not U)) or ((not U) and U) = U or U = U Thank U! Best regards, Juergen