3 ideas
3299 | In logic identity involves reflexivity (x=x), symmetry (if x=y, then y=x) and transitivity (if x=y and y=z, then x=z) [Baillie] |
13007 | Archimedes defined a straight line as the shortest distance between two points [Archimedes, by Leibniz] |
9141 | Abstraction theories build mathematics out of second-order equivalence principles [Cook/Ebert] |