User Ulrik Buchholtz

10 votes

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Arithmetic strength of Peano + the Howard ordinal

answered Dec 8, 2012 at 18:55

9 votes

Reference request for type theory

answered Mar 23, 2010 at 15:16

8 votes

Theorems for nothing (and the proofs for free)

answered Nov 22, 2009 at 5:02

8 votes

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Is any true sentence in the second-order Peano Axioms provable

answered Feb 7, 2010 at 23:23

8 votes

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Reduction rules for inductive types

answered Jan 2, 2012 at 16:54

8 votes

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Relationship between infinite suspension $\Sigma^{\infty}$ of $E_{\infty}$ grouplike space and its infinite delooping?

answered Sep 4 at 17:12

7 votes

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Subcountability

answered Dec 14, 2021 at 18:28

7 votes

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categorifying induction in homotopy type theory

answered Jun 9, 2011 at 17:33

7 votes

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Natural $\Pi^1_2$ (or worse) classes of structures?

answered Oct 27, 2013 at 1:00

6 votes

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A question about ordinal analysis

answered Feb 4, 2018 at 21:35

5 votes

Has the Ramified Theory of Types been applied to NBG?

answered Aug 18, 2018 at 10:47

5 votes

Stronger theorem not resulting from proof analysis

answered Sep 26, 2021 at 16:38

5 votes

Can the Burgess-Hazen analysis of Predicative Arithmetic be extended to Transfinite Types?

answered Dec 1, 2013 at 19:42

5 votes

Ackermann-related function

answered Mar 29, 2010 at 15:38

4 votes

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What restriction(s) of Goedel's primitive recursive functionals is (are) necessary and sufficient to prove the consistency of $PRA$

answered Jan 29, 2016 at 4:23

4 votes

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Help with simple homotopy type theory proof

answered Oct 30, 2016 at 13:56

3 votes

Mechanically instantiating abstract constructions

answered Apr 10, 2010 at 6:55

3 votes

Is there any proof assistant based on first-order logic?

answered Feb 18, 2010 at 16:37

3 votes

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Using HoTT, why is twisted cohomology of BG group cohomology?

answered Mar 12, 2021 at 12:56

2 votes

Why no morphisms from the contradictory proposition to the inconsistent context?

answered Feb 14, 2012 at 0:36

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20 Answers

Arithmetic strength of Peano + the Howard ordinal

Reference request for type theory

Theorems for nothing (and the proofs for free)

Is any true sentence in the second-order Peano Axioms provable

Reduction rules for inductive types

Relationship between infinite suspension $\Sigma^{\infty}$ of $E_{\infty}$ grouplike space and its infinite delooping?

Subcountability

categorifying induction in homotopy type theory

Natural $\Pi^1_2$ (or worse) classes of structures?

A question about ordinal analysis

Has the Ramified Theory of Types been applied to NBG?

Stronger theorem not resulting from proof analysis

Can the Burgess-Hazen analysis of Predicative Arithmetic be extended to Transfinite Types?

Ackermann-related function

What restriction(s) of Goedel's primitive recursive functionals is (are) necessary and sufficient to prove the consistency of $PRA$

Help with simple homotopy type theory proof

Mechanically instantiating abstract constructions

Is there any proof assistant based on first-order logic?

Using HoTT, why is twisted cohomology of BG group cohomology?

Why no morphisms from the contradictory proposition to the inconsistent context?