42 ideas
| 7914 | To try to be wise all on one's own is folly [Rochefoucauld] |
| 9672 | Free logic is one of the few first-order non-classical logics [Priest,G] |
| 9697 | X1 x X2 x X3... x Xn indicates the 'cartesian product' of those sets [Priest,G] |
| 9685 | <a,b&62; is a set whose members occur in the order shown [Priest,G] |
| 9674 | {x; A(x)} is a set of objects satisfying the condition A(x) [Priest,G] |
| 9673 | {a1, a2, ...an} indicates that a set comprising just those objects [Priest,G] |
| 9675 | a ∈ X says a is an object in set X; a ∉ X says a is not in X [Priest,G] |
| 9677 | Φ indicates the empty set, which has no members [Priest,G] |
| 9676 | {a} is the 'singleton' set of a (not the object a itself) [Priest,G] |
| 9678 | X⊆Y means set X is a 'subset' of set Y [Priest,G] |
| 9679 | X⊂Y means set X is a 'proper subset' of set Y [Priest,G] |
| 9681 | X = Y means the set X equals the set Y [Priest,G] |
| 9683 | X ∩ Y indicates the 'intersection' of sets X and Y, the objects which are in both sets [Priest,G] |
| 9684 | Y - X is the 'relative complement' of X with respect to Y; the things in Y that are not in X [Priest,G] |
| 9682 | X∪Y indicates the 'union' of all the things in sets X and Y [Priest,G] |
| 9692 | The 'union' of two sets is a set containing all the things in either of the sets [Priest,G] |
| 9693 | The 'intersection' of two sets is a set of the things that are in both sets [Priest,G] |
| 9694 | The 'relative complement' is things in the second set not in the first [Priest,G] |
| 9698 | The 'induction clause' says complex formulas retain the properties of their basic formulas [Priest,G] |
| 9696 | A 'cartesian product' of sets is the set of all the n-tuples with one member in each of the sets [Priest,G] |
| 9686 | A 'set' is a collection of objects [Priest,G] |
| 9687 | A 'member' of a set is one of the objects in the set [Priest,G] |
| 9695 | An 'ordered pair' (or ordered n-tuple) is a set with its members in a particular order [Priest,G] |
| 9688 | A 'singleton' is a set with only one member [Priest,G] |
| 9689 | The 'empty set' or 'null set' has no members [Priest,G] |
| 9690 | A set is a 'subset' of another set if all of its members are in that set [Priest,G] |
| 9691 | A 'proper subset' is smaller than the containing set [Priest,G] |
| 9680 | The empty set Φ is a subset of every set (including itself) [Priest,G] |
| 19419 | Not all of perception is accompanied by consciousness [Leibniz] |
| 7118 | La Rochefoucauld's idea of disguised self-love implies an unconscious mind [Rochefoucauld, by Sartre] |
| 19421 | Souls act as if there were no bodies, and bodies act as if there were no souls [Leibniz] |
| 19420 | Death and generation are just transformations of an animal, augmented or diminished [Leibniz] |
| 7912 | Judging by effects, love looks more like hatred than friendship [Rochefoucauld] |
| 7915 | Supreme cleverness is knowledge of the real value of things [Rochefoucauld] |
| 7917 | Realising our future misery is a kind of happiness [Rochefoucauld] |
| 7913 | Virtue doesn't go far without the support of vanity [Rochefoucauld] |
| 7916 | True friendship is even rarer than true love [Rochefoucauld] |
| 9299 | We are bored by people to whom we ourselves are boring [Rochefoucauld] |
| 19416 | Not all of matter is animated, any more than a pond full of living fish is animated [Leibniz] |
| 19422 | Every particle of matter contains organic bodies [Leibniz] |
| 19418 | Mechanics shows that all motion originates in other motion, so there is a Prime Mover [Leibniz] |
| 19417 | All substances are in harmony, even though separate, so they must have one divine cause [Leibniz] |