Quote:
Originally Posted by Chris Card
Why?
If A is lying then it's not true that C and D are lying, which means C or D or both are telling the truth.
Chris

You are indeed correct if one interprets A's statement in the manner you
suggest.
i.e. the negation of "C and D are lying" is C *or* D is telling the truth
and not "C *and* D are telling the truth".