30 ideas
10888 | Sets can be defined by 'enumeration', or by 'abstraction' (based on a property) [Zalabardo] |
10889 | The 'Cartesian Product' of two sets relates them by pairing every element with every element [Zalabardo] |
10890 | A 'partial ordering' is reflexive, antisymmetric and transitive [Zalabardo] |
10886 | Determinacy: an object is either in a set, or it isn't [Zalabardo] |
10887 | Specification: Determinate totals of objects always make a set [Zalabardo] |
10897 | A first-order 'sentence' is a formula with no free variables [Zalabardo] |
10893 | Γ |= φ for sentences if φ is true when all of Γ is true [Zalabardo] |
10899 | Γ |= φ if φ is true when all of Γ is true, for all structures and interpretations [Zalabardo] |
10896 | Propositional logic just needs ¬, and one of ∧, ∨ and → [Zalabardo] |
10898 | The semantics shows how truth values depend on instantiations of properties and relations [Zalabardo] |
10902 | We can do semantics by looking at given propositions, or by building new ones [Zalabardo] |
10892 | We make a truth assignment to T and F, which may be true and false, but merely differ from one another [Zalabardo] |
10900 | Logically true sentences are true in all structures [Zalabardo] |
10895 | 'Logically true' (|= φ) is true for every truth-assignment [Zalabardo] |
10901 | Some formulas are 'satisfiable' if there is a structure and interpretation that makes them true [Zalabardo] |
10894 | A sentence-set is 'satisfiable' if at least one truth-assignment makes them all true [Zalabardo] |
10903 | A structure models a sentence if it is true in the model, and a set of sentences if they are all true in the model [Zalabardo] |
10891 | If a set is defined by induction, then proof by induction can be applied to it [Zalabardo] |
17486 | Supervenience is simply modally robust property co-variance [Hendry] |
17481 | Nuclear charge (plus laws) explains electron structure and spectrum, but not vice versa [Hendry] |
20082 | Bodily movements are not actions, which are really the tryings within bodily movement [Hornsby, by Stout,R] |
17478 | Maybe two kinds are the same if there is no change of entropy on isothermal mixing [Hendry] |
17484 | Maybe the nature of water is macroscopic, and not in the microstructure [Hendry] |
17479 | The nature of an element must survive chemical change, so it is the nucleus, not the electrons [Hendry] |
17485 | Maybe water is the smallest part of it that still counts as water (which is H2O molecules) [Hendry] |
17482 | Compounds can differ with the same collection of atoms, so structure matters too [Hendry] |
17483 | Water continuously changes, with new groupings of molecules [Hendry] |
17476 | Elements survive chemical change, and are tracked to explain direction and properties [Hendry] |
17477 | Defining elements by atomic number allowed atoms of an element to have different masses [Hendry] |
17480 | Generally it is nuclear charge (not nuclear mass) which determines behaviour [Hendry] |