# 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.

**-4**

**0**answers

### A few model theoretical questions on the *SR* type of $Peano Arithmetic$

**5**

**2**answers

### Characterizing “bounded” distributivity in terms of dense open sets

**5**

**0**answers

### Topological applications of $\mathfrak{p}=\mathfrak{t}$

**6**

**1**answer

### Failure of GCH at a strongly compact cardinal

**0**

**1**answer

### Smallest $\beta$ such that it is provable that $2^{\aleph_\beta} > 2^{\aleph_0}$

**11**

**3**answers

### Infinite descending consistency chains

**2**

**0**answers

### What is the computational complexity of equivalence up to a critical point in the one generator free self-distributive algebra?

**-1**

**1**answer

### What is the consistency strength of this kind of iterating Berkeley cardinals?

**3**

**0**answers

### Proof that superstable theories with no Vaughtian pairs have no imaginary Vaughtian pairs

**55**

**9**answers

### Arguments against large cardinals

**1**

**0**answers

### Is it possible to construct a formal language that allows to refer to specific real numbers that encode ordinals accidentally writable by an ITTM?

**-3**

**0**answers

### How to write a function defined by segments in a formula? [closed]

**2**

**2**answers

### Modal logic - satisfiability

**48**

**10**answers

### What are some important but still unsolved problems in mathematical logic?

**1**

**1**answer

### ZFC ability to express truth and $\omega$ - consistency

**3**

**0**answers

### Can algebras of elementary embeddings be sufficiently described by two element subalgebras?

**6**

**0**answers

### If $j_{1},…,j_{n}:V_{\lambda+1}\rightarrow V_{\lambda+1}$ are elementary embeddings, then does $j_{1}(A)=…=j_{n}(A)=A$ for some linear order $A$?

**23**

**5**answers

### How do we construct the Gödel’s sentence in Martin-Löf type theory?

**15**

**1**answer

### Axiom of Choice versus V=L in opposition to large cardinals

**5**

**2**answers

### Cases where multiple induction steps are provably required

**209**

**29**answers

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

**8**

**0**answers

### Proper classes in Bounded Zermelo set theory

**1**

**0**answers

### Consistency of reflective sequences

**5**

**1**answer

### Given B,C incomplete, incomparable r.e. sets must C compute low r.e. set avoiding cone below B? (ADDED: Uniformly?)

**13**

**1**answer

### Is there a constructive proof that in four dimensions, the PL and the smooth category are equivalent?

**10**

**2**answers

### Is the existence of double complement of a set provable in Intuitionistic ZF?

**2**

**1**answer

### Henkin-style completeness proofs for intuitionistic logic

**2**

**2**answers

### Meta-incomputability

**2**

**1**answer

### System T, System F and arithmetical hierarchy

**7**

**2**answers

### Syntax/semantics conflation leads to infinitary logic

**0**

**1**answer

### Why the restrictions in the definition of Berkeley cardinals?

**-4**

**2**answers

### What happens if I replace a *unique natural number* that form a commutative Monoid with *the set of integers* Z that form a commutative Ring? [closed]

**19**

**1**answer

### Fubini without CH

**10**

**1**answer

### The least admissible above a dominating real

**-3**

**1**answer

### Can there be elementary embedding between a universe and a universe inside it?

**17**

**7**answers

### Understanding Specker's disproof of the axiom of choice in New Foundations

**9**

**0**answers

### Reverse Mathematics of Euclid's theorem

**13**

**4**answers

### Are there textbooks on logic where the references to set theory appear only after the construction of set theory?

**0**

**0**answers

### What is the consistency status of this theory?

**0**

**1**answer

### Strength of BTEE

**0**

**0**answers

### Is there a clear inconsistency with intense reflection of top properties of the universe?

**11**

**0**answers

### Consistency strength of $j:L_δ→L_δ$ for some δ

**2**

**1**answer

### Can Ackermann set theory find a natural interpretation in light\heavy class dichotomy?

**8**

**0**answers

### α-Mahlo vs weakly compact cardinals

**1**

**0**answers

### Questions in proof theory (PRA-provability of EA-theorems, Girards book from '87)

**0**

**0**answers

### Are the HBL derivability conditions necessary for Gödel's incompleteness theorems? (For Löb's theorem?)

**0**

**0**answers

### Shepherdson's conditions - a shortcut to the second incompleteness theorem?

**16**

**1**answer

### How is this fixed point theorem related to the axiom of choice?

**1**

**0**answers

### n-consistency - provability/truth of $\Sigma^0_n$ and $\Pi^0_{n+1}$ -formulas; n-consistent extensions, etc

**9**

**3**answers