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- Discussion Type
- discussion topicequivariant rational homotopy theory
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Oct 2nd 2020

added pointer to:

- Laura Scull,
*A model category structure for equivariant algebraic models*, Transactions of the American Mathematical Society 360 (5), 2505-2525, 2008 (doi:10.1090/S0002-9947-07-04421-2)

- Laura Scull,

- Discussion Type
- discussion topicphase transition
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Oct 2nd 2020

a stub, for the moment just to record a reference

(“phase transition” used to redirect to

*thermodynamic limit*)

- Discussion Type
- discussion topicAlex Cole
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 2nd 2020

- Discussion Type
- discussion topictopological data analysis
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Oct 2nd 2020

added this pointer:

- Gunnar Carlsson,
*Topology and data*, Bull. Amer. Math. Soc. 46 (2009), 255-308 (doi:10.1090/S0273-0979-09-01249-X)

- Gunnar Carlsson,

- Discussion Type
- discussion topiceffect algebra
- Category Latest Changes
- Started by Stephan A Spahn
- Comments 14
- Last comment by nLab edit announcer
- Last Active Oct 2nd 2020

I created effect algebra.

- Discussion Type
- discussion topicdagger category
- Category Latest Changes
- Started by Urs
- Comments 16
- Last comment by Ulrik
- Last Active Oct 2nd 2020

I took the liberty of incorporating material from Andre Joyal's latest message to the CatTheory mailing list into the entry dagger-category:

created sections

- Discussion Type
- discussion topicsuper infinity-groupoid
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active Oct 2nd 2020

created super infinity-groupoid

(to be distinguished from smooth super infinity-groupoid!)

currently the main achievement of the page is to list lots of literature in support of the claim that the site of superpoints is the correct site to consider here.

- Discussion Type
- discussion topiccofunctor
- Category Latest Changes
- Started by BryceClarke
- Comments 3
- Last comment by Urs
- Last Active Oct 2nd 2020

- Discussion Type
- discussion topicJordan-Lie-Banach algebra
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by TobyBartels
- Last Active Oct 1st 2020

created stub for Jordan-Lie-Banach algebra

- Discussion Type
- discussion topicGoutam Mukherjee
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 1st 2020

brief

`category:people`

-entry for hyperlinking references at*twisted Bredocn cohomology*

- Discussion Type
- discussion topictwisted Bredon cohomology
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Oct 1st 2020

- Discussion Type
- discussion topictwisted ordinary cohomology
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Oct 1st 2020

added pointer to:

Norman Steenrod,

*Homology With Local Coefficients*, Annals of Mathematics, Second Series, Vol. 44, No. 4 (Oct., 1943), pp. 610-627 (jstor:1969099)M. Bullejos, E. Faro, M. A. García-Muñoz,

*Homotopy colimits and cohomology with local coefficients*, Cahiers de Topologie et Géométrie Différentielle Catégoriques, 44 no. 1 (2003), p. 63-80 (numdam:CTGDC_2003__44_1_63_0)

- Discussion Type
- discussion topicstable homotopy theory
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Oct 1st 2020

I have tried to improve the list of references at

*stable homotopy theory*and related entries a bit. I think the key for having a satisfactory experience with the non-$\infty$-categorical literature reflecting the state of the art, is to first have a general but quick survey, and then turn for the details of highly structured ring spectra to a comprehensive reference on S-modules or orthogonal spectra. So I have tried to make that better visible in the list of reference.I find that for the first point (general but quick survey) Malkiewich 14 is the best that I have seen.

Of the highly structured models, probably orthogonal spectra maximize efficiency. A slight issue as far as references go is that the maybe best comprehensive account of their theory is Schwede’s

*Global homotopy theory*, which presents something more general than beginners may want to see (on the other hand, beginners often don’t know what they*really*want). In any case, I have kept adding this book reference as a reference for orthogonal spectra, joint with the comment that the inclined reader is to chooce the collection $\mathcal{F}$ of groups as trivial, throughout.

- Discussion Type
- discussion topicquark bag model
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active Sep 30th 2020

- Discussion Type
- discussion topicmereology
- Category Latest Changes
- Started by Thomas Holder
- Comments 1
- Last comment by Thomas Holder
- Last Active Sep 29th 2020

- Discussion Type
- discussion topicvector G-space
- Category Latest Changes
- Started by Urs
- Comments 6
- Last comment by Urs
- Last Active Sep 29th 2020

Recording the result from Triantafillou 82, characterizing injective/projective objects in diagrams of vector spaces over (the opposite of) the orbit category.

(The degreewise ingredients in the rational model for topological G-spaces)

- Discussion Type
- discussion topicsimplicial principal bundle
- Category Latest Changes
- Started by Urs
- Comments 11
- Last comment by Urs
- Last Active Sep 29th 2020

am splitting off simplicial principal bundle from simplicial group

- Discussion Type
- discussion topiceffective quantum field theory
- Category Latest Changes
- Started by Urs
- Comments 16
- Last comment by Urs
- Last Active Sep 29th 2020

at effective quantum field theory I have started writing an Idea-section and added more reference

- Discussion Type
- discussion topichigher-order logic
- Category Latest Changes
- Started by David_Corfield
- Comments 2
- Last comment by NikolajK
- Last Active Sep 28th 2020

- Discussion Type
- discussion topiccofiber sequence
- Category Latest Changes
- Started by nLab edit announcer
- Comments 1
- Last comment by nLab edit announcer
- Last Active Sep 28th 2020

- Discussion Type
- discussion topicmodel structure for L-infinity algebras
- Category Latest Changes
- Started by Urs
- Comments 20
- Last comment by Urs
- Last Active Sep 28th 2020

have started model structure for L-infinity algebras

- Discussion Type
- discussion topichierarchy problem
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Sep 27th 2020

Added specific pointer to argument for solution of hierarchy problem due to Acharya-Kane-Kumar 12.

- Discussion Type
- discussion topicconvenient category of topological spaces
- Category Latest Changes
- Started by Todd_Trimble
- Comments 23
- Last comment by DavidRoberts
- Last Active Sep 27th 2020

As I’ve already said elsewhere, I’ve been working on this entry and trying to give a precise definition based on my hunches of what guys like Steenrod really meant by “a convenient category of topological spaces”. (I must immediately admit that I’ve never read his paper with that title. Of course, he meant specifically compactly generated Hausdorff spaces, but nowadays I think we can argue more generally.)

I also said elsewhere that my proposed axiom on closed and open subspaces might be up for discussion. The other axioms maybe not so much: dropping any of them would seem to be a deal-breaker for what an algebraic topologist might consider “convenient”. Or so I think.

- Discussion Type
- discussion topicmodified Bernoulli number
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by nLab edit announcer
- Last Active Sep 27th 2020

- Discussion Type
- discussion topicprojective resolution
- Category Latest Changes
- Started by Urs
- Comments 32
- Last comment by Urs
- Last Active Sep 27th 2020

At

*projective resolution*I havespelled out the

*Definition*in lots of detail;spelled out statement and proof of the

*existence of resolutions*in full detail.

- Discussion Type
- discussion topicUrs Stammbach
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Sep 27th 2020

brief

`category:people`

-entry for hyperlinking references at*homological algebra*

- Discussion Type
- discussion topicinjective envelope
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Sep 27th 2020

added pointer to:

- Peter Hilton, Urs Stammbach, Section I.9 in:
*A course in homological algebra*, Springer-Verlag, New York, 1971, Graduate Texts in Mathematics, Vol. 4 (doi, pdf)

- Peter Hilton, Urs Stammbach, Section I.9 in:

- Discussion Type
- discussion topicThe Joy of Cats
- Category Latest Changes
- Started by DavidRoberts
- Comments 2
- Last comment by Urs
- Last Active Sep 27th 2020

I edited The Joy of Cats to link to metacategory and to disambiguate quasicategory, as twice now someone on MO has used the term ’quasicategory’ to talk about (very) large categories. This way, if people find the book using the nLab page they are forewarned.

I also edited quasicategory to move the terminological warning up to the idea section where it is immediately visible, rather than in the second section, below the definition.

- Discussion Type
- discussion topicKan extension
- Category Latest Changes
- Started by Mike Shulman
- Comments 53
- Last comment by Urs
- Last Active Sep 27th 2020

I think the line between the two types of Kan extension (weak versus pointwise) is drawn at the wrong place. Am I missing something?

- Discussion Type
- discussion topicKähler manifold
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by nLab edit announcer
- Last Active Sep 26th 2020

added publication data to

- Andrei Moroianu,
*Lectures on Kähler Geometry*, Cambridge University Press 2007 (arXiv:math/0402223 doi:10.1017/CBO9780511618666, pdf)

and pointer to section 11.1 there for Kaehler structures as torsion-free $U(n)$-structures

- Andrei Moroianu,