4 ideas
18465 | An 'equivalence' relation is one which is reflexive, symmetric and transitive [Kunen] |
9783 | While no two classes coincide in membership, there are distinct but coextensive attributes [Cartwright,R] |
1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |