4 ideas
9565 | Zermelo made 'set' and 'member' undefined axioms [Zermelo, by Chihara] |
3339 | For Zermelo's set theory the empty set is zero and the successor of each number is its unit set [Zermelo, by Blackburn] |
19699 | A Gettier case is a belief which is true, and its fallible justification involves some luck [Hetherington] |
22352 | Out of more than a hundred planets, Earth is the only one with the idea of free will [Vonnegut] |