# Questions tagged [lo.logic]

first-order and higher-order logic, model theory, set theory, proof theory, computability theory, formal languages, definability, interplay of syntax and semantics, constructive logic, intuitionism, philosophical logic, modal logic, completeness, Gödel incompleteness, decidability, undecidability, theories of truth, truth revision, consistency.

**71**

**16**answers

### When are two proofs of the same theorem really different proofs

**2**

**2**answers

### Minimal axiom system for a set of provable statements

**3**

**3**answers

### Is there a formula phi s.t. phi and not-phi have a stronger consistency?

**7**

**7**answers

### A few questions on model theory, especially model theory of rings

**13**

**7**answers

### Is no proof based on “tertium non datur” sufficient any more after Gödel?

**8**

**1**answer

### Controlling Ultrapowers

**10**

**3**answers

### Intuitionistic Lowenheim-Skolem?

**7**

**1**answer

### Actions of finite permutation groups on hereditarily finite sets.

**6**

**2**answers

### Cofinality of Theta if sharps exist

**35**

**5**answers

### Several Topos theory questions

**11**

**4**answers

### Why do I find Category Theory mostly just a way to make simple things difficult?

**209**

**29**answers

### What are some reasonable-sounding statements that are independent of ZFC?

**9**

**4**answers

### Does Cantor-Bernstein hold for classes?

**13**

**7**answers

### Intro to automatic theorem proving / logical foundations?

**14**

**7**answers

### What is lambda calculus related to?

**7**

**10**answers

### What do models where the CH is false look like?

**27**

**6**answers

### Does finite mathematics need the axiom of infinity?

**20**

**6**answers

### What is a topos?

**9**

**2**answers