3 ideas
17750 | The first clear proof of the consistency of the first order predicate logic was in 1928 [Hilbert/Ackermann, by Walicki] |
21548 | The null class is the class with all the non-existents as its members [MacColl, by Lackey] |
604 | Knowledge is mind and knowing 'cohabiting' [Lycophron, by Aristotle] |