Combining Texts

All the ideas for 'fragments/reports', 'Dynamic Logics' and 'Elements of Set Theory'

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

---

10 ideas

4. Formal Logic / E. Nonclassical Logics / 11. Dynamic Logics

15381

Dyamic logics model changes between classical states, in action, belief, and computing [Uckelman]

4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST

13201

∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton]

13204

The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton]

13206

A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton]

4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set

13200

Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton]

13199

The empty set may look pointless, but many sets can be constructed from it [Enderton]

4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets

13203

The singleton is defined using the pairing axiom (as {x,x}) [Enderton]

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / h. Axiom of Replacement VII

13202

Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton]

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX

13205

We can only define functions if Choice tells us which items are involved [Enderton]

23. Ethics / A. Egoism / 1. Ethical Egoism

3031	The greatest good is not the achievement of desire, but to desire what is proper [Menedemus, by Diog. Laertius]