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- Discussion Type
- discussion topicequivariant stable homotopy theory
- Category Latest Changes
- Started by Urs
- Comments 11
- Last comment by Urs
- Last Active May 19th 2019

I am slowly creating a bunch of entries on basic concepts of equivariant stable homotopy theory, such as

- equivariant suspension spectrum, equivariant sphere spectrum, equivariant homotopy groups, RO(G)-grading, fixed point spectrum, tom Dieck splitting

At the moment I am mostly just indexing Stefan Schwede’s

- Discussion Type
- discussion topicBorel equivariant cohomology
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active May 19th 2019

- Discussion Type
- discussion topicdifferentiable stack
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 19th 2019

I have added pdf-links to the reference

- David Carchedi,
*Categorical Properties of Topological and Diffentiable Stacks*, PhD thesis, Universiteit Utrecht, 2011 (dspace:1874/208971, pdf)

and promoted this to the top of the list, since I suppose this is the most comprehensive account that a reader might want to go to first. Will also edit accordingly at

*topological stack*- David Carchedi,

- Discussion Type
- discussion topicJohn Ratcliffe
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by DavidRoberts
- Last Active May 19th 2019

brief

`category:people`

-entry for hyperlinking references at*orbifold*and*hyperbolic manifold*, in particular to this excellent book:- John Ratcliffe,
*Foundations of Hyperbolic Manifolds*, Springer 2006 (doi:10.1007/978-0-387-47322-2, pdf)

- John Ratcliffe,

- Discussion Type
- discussion topicmultiverse
- Category Latest Changes
- Started by Urs
- Comments 35
- Last comment by Urs
- Last Active May 19th 2019

I kept being annoyed about the nature of discussion of the “multiverse” (the one in cosmology, not the one in set theory). Now I thought instead of steadily being annoyed, I should start an $n$Lab entry that does it better. So I did now (or tried to), at

*multiverse*.

- Discussion Type
- discussion topicYoneda lemma
- Category Latest Changes
- Started by Urs
- Comments 72
- Last comment by Mike Shulman
- Last Active May 19th 2019

Todd,

you added to Yoneda lemma the sentence

In brief, the principle is that the identity morphism $id_x: x \to x$ is the universal generalized element of $x$. This simple principle is surprisingly pervasive throughout category theory.

Maybe it would be good to expand on that. One might think that the universal property of a genralized element is that every other one factors through it uniquely. That this is true for the generalized element $id_x$ is a tautological statement that does not need or imply the Yoneda lemma, it seems.

- Discussion Type
- discussion topicNico Courts
- Category Latest Changes
- Started by nLab edit announcer
- Comments 1
- Last comment by nLab edit announcer
- Last Active May 18th 2019

- Discussion Type
- discussion topicJames Liu
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 18th 2019

- Discussion Type
- discussion topicduality between heterotic and type II string theory
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active May 18th 2019

- Discussion Type
- discussion topicstring-string duality
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active May 18th 2019

- Discussion Type
- discussion topicRamzi Khuri
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 18th 2019

- Discussion Type
- discussion topicstring coupling constant
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 18th 2019

- Discussion Type
- discussion topicRoberto Volpato
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 18th 2019

brief

`category:people`

-entry for hyperlinking references at*moonshine*,*duality between heterotic and type II string theory*,*Riemannian orbifold*and maybe elsewhere

- Discussion Type
- discussion topicallegory
- Category Latest Changes
- Started by Todd_Trimble
- Comments 40
- Last comment by Daniel Luckhardt
- Last Active May 18th 2019

Added some examples to allegory, including that of modular lattice as one-object allegory.

- Discussion Type
- discussion topic2-spectral triple
- Category Latest Changes
- Started by Urs
- Comments 14
- Last comment by Urs
- Last Active May 18th 2019

added more references to 2-spectral triple (as far as I can see Jürg Fröhlich with his students was the first to try to formalize this to some extent)

- Discussion Type
- discussion topicfolklore
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Urs
- Last Active May 18th 2019

felt like archiving a quote by Paul Taylor somewhere, it is now at

*folklore*.Besides being funny, it is actually a useful comment for the newbie, and so I linked to it from

*category theory*.

- Discussion Type
- discussion topicFQFT
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active May 18th 2019

I am beginning to give the entry

*FQFT*a comprehensive*Exposition and Introduction*section.So far I have filled some genuine content into the first subsection

*Quantum mechanics in Schrödinger picture*.But I have to quit now. This isn’t even proof-read yet. So don’t look at it unless you feel more in editing-mood than in pure-reading-mood.

- Discussion Type
- discussion topicaugmented simplicial set
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by atmacen
- Last Active May 18th 2019

I noticed that augmented simplicial set did not point anywhere, so i created the entry. But have no energy to put anything of substance there right now.

- Discussion Type
- discussion topicvacua -- contents
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 17th 2019

- Discussion Type
- discussion topicautomorphism of a vertex operator algebra
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active May 17th 2019

- Discussion Type
- discussion topicmonster group
- Category Latest Changes
- Started by Todd_Trimble
- Comments 10
- Last comment by Urs
- Last Active May 17th 2019

Over at Monster group, I wrote out a description via a group presentation. Of course, it makes no pretense to be illuminating (although it is well-known to experts like Conway; it’s probably in his book with Sloane on the Leech lattice and sphere packings).

- Discussion Type
- discussion topicMonster vertex operator algebra
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 17th 2019

added pointer to

*automorphisms of a super vertex operator algebra*and to- Robert Griess Jr., Ching Hung Lam,
*A new existence proof of the Monster by VOA theory*(arXiv:1103.1414)

- Robert Griess Jr., Ching Hung Lam,

- Discussion Type
- discussion topicnumber of supersymmetries
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 17th 2019

- Discussion Type
- discussion topicAdS-CFT
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active May 17th 2019

- Discussion Type
- discussion topicOrbifolds in Mathematics and Physics
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active May 17th 2019

- Discussion Type
- discussion topicSpin(9)
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by David_Corfield
- Last Active May 17th 2019

- Discussion Type
- discussion topicCayley plane
- Category Latest Changes
- Started by Mike Shulman
- Comments 2
- Last comment by David_Corfield
- Last Active May 17th 2019

I made Cayley plane a little less stubby.

- Discussion Type
- discussion topicbosonic M-theory
- Category Latest Changes
- Started by David_Corfield
- Comments 1
- Last comment by David_Corfield
- Last Active May 17th 2019

- Discussion Type
- discussion topicexceptional structure
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by David_Corfield
- Last Active May 17th 2019

- Discussion Type
- discussion topicRobert A. Wilson
- Category Latest Changes
- Started by David_Corfield
- Comments 1
- Last comment by David_Corfield
- Last Active May 17th 2019