# 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.

**2**

**1**answer

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

**-1**

**1**answer

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

**2**

**0**answers

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

**3**

**0**answers

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

**11**

**3**answers

### Infinite descending consistency chains

**-3**

**0**answers

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

**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

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

**1**

**1**answer

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

**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 $A$?

**15**

**1**answer

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

**8**

**0**answers

### Proper classes in Bounded Zermelo set theory

**1**

**0**answers

### Consistency of reflective sequences

**13**

**1**answer

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

**2**

**1**answer

### Henkin-style completeness proofs for intuitionistic logic

**5**

**2**answers

### Cases where multiple induction steps are provably required

**5**

**1**answer

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

**-1**

**1**answer

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

**2**

**1**answer

### System T, System F and arithmetical hierarchy

**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

**7**

**2**answers

### Syntax/semantics conflation leads to infinitary logic

**-3**

**1**answer

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

**9**

**0**answers

### Reverse Mathematics of Euclid's theorem

**0**

**1**answer

### Strength of BTEE

**0**

**0**answers

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

**0**

**0**answers

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

**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?)

**16**

**1**answer

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

**0**

**0**answers

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

**2**

**1**answer

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

**1**

**0**answers

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

**11**

**0**answers

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

**0**

**0**answers

### Is Reflective Set Theory stronger than $\small {\mathsf{ARC}}$?

**1**

**0**answers

### Does this axiomatic system satisfy requirements for founding mathematics?

**1**

**1**answer

### Downward density of w-REA sets under arithmetic reducibility?

**2**

**1**answer

### Correct Proof Of ZBC Theorem From Odifreddi? Also Extension Question

**1**

**1**answer

### On a combinatorial set covering property

**0**

**0**answers

### Can reflection in $V$ and reflection out of $V$ principles be used in the same theory?

**4**

**0**answers

### Can this reflective class theory interpret ZFC?

**0**

**1**answer

### Superintuitionistic logics which are not hereditary/monotonic: impossible or possible?

**7**

**1**answer

### Effective set= ordinal definable set

**0**

**0**answers

### What is the limit to iterating class comprehension, reflection and limitation of size?

**8**

**0**answers

### Reflection principle for intuitionistic Zermelo–Fraenkel?

**22**

**1**answer

### Is there a short proof of the decidability of Kepler's Conjecture?

**3**

**1**answer

### What is the strength of adding limitation of size and a simple version of reflection to Ackermann set theory?

**6**

**0**answers