16 ideas
| 13201 | ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton] |
| 13206 | A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton] |
| 13204 | The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton] |
| 13200 | Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton] |
| 13199 | The empty set may look pointless, but many sets can be constructed from it [Enderton] |
| 13203 | The singleton is defined using the pairing axiom (as {x,x}) [Enderton] |
| 13202 | Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton] |
| 13205 | We can only define functions if Choice tells us which items are involved [Enderton] |
| 16129 | Evans argues (falsely!) that a contradiction follows from treating objects as vague [Evans, by Lowe] |
| 16459 | Is it coherent that reality is vague, identities can be vague, and objects can have fuzzy boundaries? [Evans] |
| 16457 | There clearly are vague identity statements, and Evans's argument has a false conclusion [Evans, by Lewis] |
| 16460 | Evans assumes there can be vague identity statements, and that his proof cannot be right [Evans, by Lewis] |
| 14484 | If a=b is indeterminate, then a=/=b, and so there cannot be indeterminate identity [Evans, by Thomasson] |
| 16224 | There can't be vague identity; a and b must differ, since a, unlike b, is only vaguely the same as b [Evans, by PG] |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |