TITLE: Negation of "and" statements: a and b
QUESTION [7 upvotes]: Is it correct?
$\neg$(a and b)=(not a) or (not b)
What ruleset can i look up for negations? Especially for  "all", "if, then" statements.

REPLY [12 votes]: Yes, that's called De Morgan's Laws. This site has more rules about negations of logical connectives and this PDF should help you with negation of universal and existential quantifiers.