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- Discussion Type
- discussion topiccohomology
- Category Latest Changes
- Started by Urs
- Comments 71
- Last comment by Urs
- Last Active Oct 22nd 2020

added a cool reference by Brian Conrad to cohomology, which was mentioned at MathOverflow

- Discussion Type
- discussion topicFinSet
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Hurkyl
- Last Active Oct 22nd 2020

I have briefly recorded the equivalence of FinSet${}^{op}$ with finite Booplean algebras at

*FinSet – Properties – Opposite category*. Then I linked to this from various related entries, such as*finite set*,*power set*,*Stone duality*,*opposite category*.(I thought we long had that information on the $n$Lab, but it seems we didn’t)

- Discussion Type
- discussion topicvector meson dominance
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Urs
- Last Active Oct 22nd 2020

- Discussion Type
- discussion topic2-pro-object
- Category Latest Changes
- Started by David_Corfield
- Comments 4
- Last comment by David_Corfield
- Last Active Oct 22nd 2020

Came across this categorification of pro-object.

- Discussion Type
- discussion topicbicategory of fractions
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 4
- Last comment by Mike Shulman
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicBorel construction
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active Oct 21st 2020

started an entry on the

*Borel construction*, indicating its relation to the nerve of the action groupoid.

- Discussion Type
- discussion topictopological G-space
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Oct 21st 2020

added pointer to Bredon 72. Will add this pointer also to various related entries on equivariant homotopy theory

- Discussion Type
- discussion topic(infinity,1)-sheaf
- Category Latest Changes
- Started by Hurkyl
- Comments 2
- Last comment by Hurkyl
- Last Active Oct 21st 2020

- Discussion Type
- discussion topictype refinement
- Category Latest Changes
- Started by David_Corfield
- Comments 2
- Last comment by David_Corfield
- Last Active Oct 21st 2020

Added a couple of references

- Paul-André Melliès, Noam Zeilberger,
*An Isbell Duality Theorem for Type Refinement Systems*, (pdf) - Robert Atkey, Patricia Johann, Neil Ghani,
*When is a Type Refinement an Inductive Type?*, (pdf)

- Paul-André Melliès, Noam Zeilberger,

- Discussion Type
- discussion topicequivariant differential topology
- Category Latest Changes
- Started by Urs
- Comments 11
- Last comment by Urs
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicproper action
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicPostnikov system
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 21st 2020

I have added pointer to the second of Postnikov’s original articles on the matter:

- M. M. Postnikov,
*Issledovaniya po gomotopičeskoĭ teorii nepreryvnyh otobraženiĭ. I. Algebraičeskaya teoriya sistem. II. Naturalʹnaya sistema i gomotopičeskiĭ tip*. (Russian) $[$_Investigations in homotopy theory of continuous mappings. I. The algebraic theory of systems. II. The natural system and homotopy type._$]$ Trudy Mat. Inst. Steklov. no. 46. Izdat. Akad. Nauk SSSR, Moscow, 1955. (mathnet:tm1182)

Is there any linkable online trace of Postnikov’s first article:

- M. M. Postnikov,
*Determination of the homology groups of a space by means of the homotopy invariants*, Doklady Akad. Nauk SSSR (N.S.) 76: 359–362 (1951)

?

- M. M. Postnikov,

- Discussion Type
- discussion topicsupernova
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicDirac-Born-Infeld action
- Category Latest Changes
- Started by Urs
- Comments 25
- Last comment by Urs
- Last Active Oct 21st 2020

added pointer to Schwarz 01

- Discussion Type
- discussion topicAdS-QCD correspondence
- Category Latest Changes
- Started by Urs
- Comments 52
- Last comment by Urs
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicexceptional field theory
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Oct 21st 2020

started some minimum at

*exceptional field theory*(the formulation of 11d supergravity that makes the exceptional U-duality symmetry manifest)

- Discussion Type
- discussion topicheterotic line bundle
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active Oct 21st 2020

- Discussion Type
- discussion topicconservative functor
- Category Latest Changes
- Started by Urs
- Comments 23
- Last comment by DavidRoberts
- Last Active Oct 20th 2020

added to

*conservative functor*the proposition saying that pullback along strong epis is a conservative functor (if strong epis pull back).How about the $\infty$-version?

- Discussion Type
- discussion topicsuper-Cartan geometry
- Category Latest Changes
- Started by David_Corfield
- Comments 26
- Last comment by David_Corfield
- Last Active Oct 20th 2020

I see super-Cartan geometry is taking shape. Will Clifford algebras make an appearance in the The super-Klein geometry: super-Minkowski spacetime section?

Is there a higher super-Cartan way of thinking about what is at 3-category of fermionic conformal nets, about the String 2-group and superstrings, as here about the spin group and fermions.

- Discussion Type
- discussion topicprecision experiment
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 20th 2020

- Discussion Type
- discussion topicQCD and strongly coupled gauge theories - challenges and perspectives
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Oct 20th 2020

- Discussion Type
- discussion topiccosmology
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 20th 2020

added pointer to:

- Anna Ijjas, Frans Pretorius, Paul Steinhardt,
*Stability and the gauge problem in non-perturbative cosmology*, Journal of Cosmology and Astroparticle Physics, Volume 2019, January 2019 (arXiv:1809.07010, doi:10.1088/1475-7516/2019/01/015)

- Anna Ijjas, Frans Pretorius, Paul Steinhardt,

- Discussion Type
- discussion topicbundle gerbe
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Oct 20th 2020

i polished the definition in bundle gerbe and then reorganized the former material on “Interpretations” in a new section

that first shows how to get a shifted central extension of groupoids form the bundle gerbe, and then demonstrates that this is the total space of a principal 2-bundle

- Discussion Type
- discussion topicKonstantin Eder
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 20th 2020

brief

`category:people`

-entry for hyperlinking references at*super Cartan geometry*and*supergravity*

- Discussion Type
- discussion topicsupergravity
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Oct 20th 2020

created supergravity

so far just an "Idea" section and a link to D'Auria-Fre formulation of supergravity (which i am busy working on)

- Discussion Type
- discussion topicgravity
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Oct 20th 2020

added to gravity references discussing the covariant phase space of gravity, as part of a reply to this TP.SE-question

- Discussion Type
- discussion topicBPST-instanton
- Category Latest Changes
- Started by DavidRoberts
- Comments 3
- Last comment by Urs
- Last Active Oct 20th 2020

- Discussion Type
- discussion topicRaffael Stenzel
- Category Latest Changes
- Started by David_Corfield
- Comments 1
- Last comment by David_Corfield
- Last Active Oct 20th 2020

- Discussion Type
- discussion topicelementary (infinity,1)-topos
- Category Latest Changes
- Started by David_Corfield
- Comments 70
- Last comment by David_Corfield
- Last Active Oct 20th 2020

I added the reference

- Nima Rasekh,
*A Theory of Elementary Higher Toposes*, (arXiv:1805.03805)

- Nima Rasekh,

- Discussion Type
- discussion topicPontryagin class
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 19th 2020

added these pointers on the first Pontrjagin class as counting gravitational instanton number:

Tohru Eguchi, Peter Freund,

*Quantum Gravity and World Topology*, Phys. Rev. Lett. 37, 1251 (1967) (doi:10.1103/PhysRevLett.37.1251)Alexander Belavin, D. Burlankov,

*The renormalisable theory of gravitation and the einstein equations*, Physics Letters A Volume 58, Issue 1, 26 July 1976, Pages 7-8 (doi:10.1016/0375-9601(76)90530-2)