14 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] |
| 20416 | By 1790 aestheticians were mainly trying to explain individual artistic genius [Kemp] |
| 20417 | Expression can be either necessary for art, or sufficient for art (or even both) [Kemp] |
| 20419 | We don't already know what to express, and then seek means of expressing it [Kemp] |
| 20418 | The horror expressed in some works of art could equallly be expressed by other means [Kemp] |
| 23812 | Force is what turns man into a thing, and ultimately into a corpse [Weil] |
| 23813 | Only people who understand force, and don't respect it, are capable of justice [Weil] |