4 ideas
7791 | The simplest of the logics based on possible worlds is Lewis's S5 [Lewis,CI, by Girle] |
11002 | Equating necessity with informal provability is the S4 conception of necessity [Lewis,CI, by Read] |
9141 | Abstraction theories build mathematics out of second-order equivalence principles [Cook/Ebert] |
7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |