Question

Can the semi-characteristic function of $\{x \mid \varphi_x(x)\downarrow\}$ be extended to a total function?

score 35 · Answer 1 · 2022-11-06 14:28:51

35

Views

Can the semi-characteristic function of $\{x \mid \varphi_x(x)\downarrow\}$ be extended to a total function?

Published on 06 Nov 2022 - 14:28

score 29 · Answer 2 · 2022-11-14 15:52:05

29

Views

Operations on computable functions

Published on 14 Nov 2022 - 15:52

score 83 · Answer 3 · 2022-11-19 14:56:06

83

Views

Indicator function of uncomputable numbers.

Published on 19 Nov 2022 - 14:56

score 77 · Answer 4 · 2022-12-16 02:25:25

77

Views

Which subsets of $\mathbb{N}$ can be the sizes of finite models?

Published on 16 Dec 2022 - 2:25

score 71 · Answer 5 · 2026-03-28 12:34:10

71

Views

What methods/objects in ZFC can't be computed and why not?

Published on 28 Mar 2026 - 12:34

score 42 · Answer 6 · 2026-02-24 08:20:57

42

Views

Proving in computability if L is subset of RE and infinity there is A ⊆ L and decidable

Published on 24 Feb 2026 - 8:20

score 348 · Answer 7 · 2026-04-06 13:11:12

348

Views

What functions from $\Bbb N\to\Bbb N$ can be made from $+$, $-$, $\times$, $\div$, exponentiation, and $\lfloor\cdot\rfloor$?

Published on 06 Apr 2026 - 13:11

score 105 · Answer 8 · 2022-12-26 17:25:42

105

Views

Books on logic, whether old books are still relevant, and modern logic research areas.

Published on 26 Dec 2022 - 17:25

score 44 · Answer 9 · 2026-04-06 06:14:27

44

Views

Understanding how to find the factors of a string

Published on 06 Apr 2026 - 6:14

score 124 · Answer 10 · 2022-12-30 17:53:42

124

Views

Prove that there is a p.c. function $θ$ such that $λx [ μy [ ψ(x, y) = 1 ] ]$ is not p.c.

Published on 30 Dec 2022 - 17:53

score 167 · Answer 11 · 2026-03-30 09:45:05

167

Views

Using non-computable numbers to compute other non-computable numbers

Published on 30 Mar 2026 - 9:45

score 21 · Answer 12 · 2023-01-06 11:40:47

21

Views

$m$-degree of a simple set contains infinitely many $1$-degrees

Published on 06 Jan 2023 - 11:40

score 50 · Answer 13 · 2026-03-30 09:46:33

50

Views

Can this language be decided in polynomial time?

Published on 30 Mar 2026 - 9:46

score 92 · Answer 14 · 2026-03-30 09:49:47

92

Views

Many-one reduction of $K^c$ to $A$

Published on 30 Mar 2026 - 9:49

score 118 · Answer 15 · 2026-02-23 03:42:49

118

Views

Is this double recursion necessarily primitive recursive?

Published on 23 Feb 2026 - 3:42

List Question

Can the semi-characteristic function of $\{x \mid \varphi_x(x)\downarrow\}$ be extended to a total function?

Operations on computable functions

Indicator function of uncomputable numbers.

Which subsets of $\mathbb{N}$ can be the sizes of finite models?

What methods/objects in ZFC can't be computed and why not?

Proving in computability if L is subset of RE and infinity there is A ⊆ L and decidable

What functions from $\Bbb N\to\Bbb N$ can be made from $+$, $-$, $\times$, $\div$, exponentiation, and $\lfloor\cdot\rfloor$?

Books on logic, whether old books are still relevant, and modern logic research areas.

Understanding how to find the factors of a string

Prove that there is a p.c. function $θ$ such that $λx [ μy [ ψ(x, y) = 1 ] ]$ is not p.c.

Using non-computable numbers to compute other non-computable numbers

$m$-degree of a simple set contains infinitely many $1$-degrees

Can this language be decided in polynomial time?

Many-one reduction of $K^c$ to $A$

Is this double recursion necessarily primitive recursive?

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