A word on notation: In all of the HTML pages (problems and exercises) we are using the following notation for propositional logic:
^ (caret) for and,
v (lower case v) for or,
~ for not,
-> (hyphen, >) for implication, and
<-> (<, hyphen, >) for biconditionals.
Propositional variables are upper case letters (and possibly numbers).
The symbols true and false are written out in lower case.