# 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**

**0**answers

### Lengths of proofs and quasilinear time

**0**

**1**answer

### What are the difficulties involved in proving that the Kunen inconsistency holds in $NGB$

**6**

**3**answers

### Are there logical systems where formal proofs are not computer verifiable?

**6**

**1**answer

### Proof of ¬(¬1 ⊗ ¬1) in tensorial logic

**11**

**2**answers

### Is being close to a Halting set computable?

**2**

**1**answer

### Is there anything against this function j being injective?

**5**

**1**answer

### Random reals preserving Cohen reals

**2**

**1**answer

### A variant of Radin forcing

**3**

**0**answers

### “Antiforcing” - Is there a method to 'remove' sets from a model of ZF?

**13**

**0**answers

### Cardinality vs. isomorphism type of vector spaces without choice

**5**

**0**answers

### Decomposition of forcing iterations

**4**

**1**answer

### Embedding ordinals with the order topology into connected $T_2$-spaces

**5**

**0**answers

### Bad forcing permutations

**5**

**0**answers

### Self-additive posets

**16**

**1**answer

### What non-standard model of arithmetic does Hofstadter reference in GEB?

**0**

**0**answers

### Would Singletons+ Boolean union+ Relative complements+ Composition terminate over sets $N, P(N), P(P(N))$?

**2**

**0**answers

### Relation of $\omega_{\omega_1+1}^{CK}$ to some other ordinals

**2**

**1**answer

### Formal definition of this ordinal?

**5**

**1**answer

### Buying more absoluteness for countable transitive models?

**7**

**0**answers

### How much can complexities of bases of a “simple” space vary?

**7**

**1**answer

### Vopenka's principle is equivalent to the existence of a strong compactness cardinal for any “logic”?

**7**

**1**answer

### Stationarity and Fodor's lemma for a (nice) poset?

**3**

**1**answer

### Going beyond the strength of Peano arithmetic “without sets”

**3**

**0**answers

### Reasonable reference index or list of the interpretability/consistency hierarchy

**2**

**0**answers

### How to decide if a recursive addition of subsets after certain formula would terminate?

**1**

**0**answers

### Looking for help in defining a new epistemic logic

**1**

**0**answers

### Proof of the Specker-Blatter theorem

**0**

**1**answer

### Can cardinality be defined with essentially no practical restriction on non-well-ordered combinatorics or ill-foundedness of sets?

**7**

**1**answer

### Is the smallest $L_\alpha$ with undefinable ordinals always countable?

**0**

**1**answer

### Probabilistic generalization of trial-and-error predicates

**3**

**1**answer

### Strong partition property + DC + existence of non-principal ultrafilter on $\omega$

**9**

**1**answer

### What is the consistency strength of weak Vopenka's principle?

**0**

**0**answers

### Consistency of Nontrivial Elementary Embedding from $\omega_1$ to itself?

**5**

**2**answers

### Complete atomless Boolean algebras with abelian automorphism group

**3**

**1**answer

### Internal equality for Eq-fibrations' morphisms

**3**

**2**answers

### What fragments of ZF are consistent with a set being equal in size to its power set?

**0**

**1**answer

### Is it consistent with Z - Regularity to have a set that is bigger than any set in the cumulative hierarchy of Z?

**5**

**0**answers

### Examples in which probabilistic heuristic reasoning fails

**9**

**2**answers

### Examples of set theory problems which are solved using methods outside of logic

**13**

**1**answer

### Does this consequence of measurability in terms of games of length $\omega+1$ imply measurability?

**10**

**0**answers

### On the Number of Parallel Automorphism Lines

**34**

**7**answers

### Paradoxical Mathematical Objects Pending for Construction [duplicate]

**8**

**1**answer

### Interpreting a space in Baire space: how many facts do I need to understand the whole thing?

**2**

**1**answer

### Is any real closed extension of $\mathbb R$ characterized up to isomorphism by its ladder?

**4**

**2**answers

### Strongly reducible but not effectively interpretable

**8**

**4**answers

### Formalizations of the idea that something is a function of something else?

**18**

**1**answer

### Proof as a Σ₁ approximation to truth: what about higher degrees?

**11**

**1**answer

### Fixed points of injective self-maps

**31**

**1**answer

### Is this conjecture strictly weaker than P=NP?

**3**

**2**answers