Combining Texts

All the ideas for 'reports', 'The Theory of Transfinite Numbers' and 'First-Order Logic'

expand these ideas     |    start again     |     specify just one area for these texts

22 ideas

4. Formal Logic / F. Set Theory ST / 1. Set Theory
9616 A set is a collection into a whole of distinct objects of our intuition or thought [Cantor]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
10282 Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
10283 A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
10284 There are three different standard presentations of semantics [Hodges,W]
10285 I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10288 Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
10289 Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
10287 If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / f. Uncountable infinities
15896 Cantor needed Power Set for the reals, but then couldn't count the new collections [Cantor, by Lavine]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
10286 A 'set' is a mathematically well-behaved class [Hodges,W]
20. Action / C. Motives for Action / 3. Acting on Reason / b. Intellectualism
7352 Jesus said learning was unnecessary, and only the spirit of the Law was needed [Jesus, by Johnson,P]
22. Metaethics / B. Value / 2. Values / g. Love
6289 Love your enemies [Jesus]
6292 Love thy neighbour as thyself [Jesus]
23. Ethics / B. Contract Ethics / 2. Golden Rule
5356 Treat others as you would have them treat you [Jesus]
23. Ethics / B. Contract Ethics / 4. Value of Authority
6286 Blessed are the merciful: for they shall obtain mercy [Jesus]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / c. Motivation for virtue
6290 Except ye become as little children, ye shall not enter heaven [Jesus]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / h. Right feelings
6287 If you lust after a woman, you have committed adultery [Jesus]
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
6285 Blessed are the meek; for they shall inherit the earth [Jesus]
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
6288 Don't resist evil, but turn the other cheek [Jesus]
23. Ethics / C. Virtue Theory / 4. External Goods / c. Wealth
6293 It is almost impossible for the rich to go to heaven [Jesus]
28. God / A. Divine Nature / 6. Divine Morality / c. God is the good
6291 No one is good except God [Jesus]
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
7351 Jesus turned the ideas of Hillel into a theology reduced to its moral elements [Jesus, by Johnson,P]