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- Discussion Type
- discussion topicVergleichende Betrachtungen über neuere geometrische Forschungen
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 4 days ago

a brief

`category:reference`

-article forFelix Klein,

*Vergleichende Betrachtungen über neuere geometrische Forschungen*(1872) Mathematische Annalen volume 43, pages 63–100 1893 (doi:10.1007/BF01446615)English translation by M. W. Haskell:

*A comparative review of recent researches in geometry*, Bull. New York Math. Soc. 2, (1892-1893), 215-249. (euclid:1183407629 KleinRetyped.pdf:file)

- Discussion Type
- discussion topicKlein geometry
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active 4 days ago

Added to

*Klein geometry*a section*History*with quotations for where exactly Klein actually speaks about $G/H$.(This key passages is a bit hidden in Klein’s text, appearing at a somewhat unexpected point somewhere in the middle of a 35 page document.)

- Discussion Type
- discussion topictopological group
- Category Latest Changes
- Started by Todd_Trimble
- Comments 29
- Last comment by Urs
- Last Active 4 days ago

The entry on topological group could stand more work, but I added some stuff on the uniform structure, in particular the proposition that for group homomorphisms $f: G \to H$, continuity at a single point guarantees uniform continuity over all of $G$. The proof is follow-your-nose, of course.

What we really need is an entry Haar measure. I’ll get started on that soon.

- Discussion Type
- discussion topicprincipal bundle
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by Urs
- Last Active 4 days ago

I have added to

*principal bundle*a remark on their

*definition*As quotients;statements about (classes of) (counter-)examples of quotients

Thanks for pointers to the literature from this MO thread!

- Discussion Type
- discussion topicquotient category
- Category Latest Changes
- Started by Mike Shulman
- Comments 3
- Last comment by zskoda
- Last Active 4 days ago

- Discussion Type
- discussion topictorsion theory, quotient category
- Category Latest Changes
- Started by zskoda
- Comments 32
- Last comment by zskoda
- Last Active 4 days ago

New entries torsion theory and quotient category.

- Discussion Type
- discussion topiccondensed set
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 47
- Last comment by Dmitri Pavlov
- Last Active 4 days ago

- Discussion Type
- discussion topicAlexis Toumi
- Category Latest Changes
- Started by alexis.toumi
- Comments 3
- Last comment by alexis.toumi
- Last Active 5 days ago

- Discussion Type
- discussion topicmathematical physics
- Category Latest Changes
- Started by zskoda
- Comments 8
- Last comment by David_Corfield
- Last Active 5 days ago

mathematical physics with a slight distinction from physical mathematics which points to the same entry. The relation to theoretical physics has been discussed, but I am not sure yet if we should have theoretical physics as a separate entry so I do not put is as another redirect.

- Discussion Type
- discussion topicStephen M. Gersten
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 1
- Last comment by Dmitri Pavlov
- Last Active 6 days ago

- Discussion Type
- discussion topicsimplicial presheaf
- Category Latest Changes
- Started by nLab edit announcer
- Comments 2
- Last comment by Dmitri Pavlov
- Last Active 6 days ago

I edited three things: - In the definition of $D_X$ I corrected what seems to be a typo : indeed $D_X([n]) = X_n$ is a presheaf over $S$, not a set (and then a simplicial presheaf, not a simplicial set)

In the definition of the notation $[-,-]$ for simplicial presheaves, I edited the domain of that functor, which is not simply $C:=SSet^{S^{op}}$, but indeed $C^{op}\times C$

In the corollary that follows the introduction of $D_X$, I changed “evaluations of $X$” into “evalutations of $A$”, because in $[X,A]$, we end up with $holim lim A(U_i)$

Anonymous

- Discussion Type
- discussion topicfilter
- Category Latest Changes
- Started by nLab edit announcer
- Comments 5
- Last comment by nLab edit announcer
- Last Active 6 days ago

- Discussion Type
- discussion topicsitus
- Category Latest Changes
- Started by nLab edit announcer
- Comments 7
- Last comment by nLab edit announcer
- Last Active 6 days ago

- Discussion Type
- discussion topicanomalous magnetic moment
- Category Latest Changes
- Started by Urs
- Comments 24
- Last comment by Urs
- Last Active 6 days ago

there is an old article (Berends-Gastman 75) that computes the 1-loop corrections due to perturbative quantum gravity to the anomalous magnetic moment of the electron and the muon. The result turns out to be independent of the choice of (“re”-)normalization (hence what they call “finite”).

I have added a remark on this in the $(g-2)$-entry here and also at

*quantum gravity*here.

- Discussion Type
- discussion topicassociated bundle
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 6 days ago

have added to

*associated bundle*an exposition, here, of how in a context of $(2,1)$-topos theory, associated bundles are naturally thought of as homotopy pullbacks of action groupoid projections.This is from one subsection of what I am currently typing into

*geometry of physics – representations and associated bundles*. It may need more polishing, but I need to interrupt now for half an hour or so.

- Discussion Type
- discussion topicfiber bundle
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 3
- Last comment by Urs
- Last Active 6 days ago

- Discussion Type
- discussion topicinvariant metric
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 6 days ago

starting some minimum, in order to give a home to this reference:

- John Milnor,
*Curvatures of left invariant metrics on lie groups*, Advances in Mathematics, Volume 21, Issue 3, September 1976, Pages 293-329 (doi:10.1016/S0001-8708(76)80002-3)

- John Milnor,

- Discussion Type
- discussion topicequivariant tubular neighbourhood
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 6 days ago

For ease of hyperlinking, I am giving this its own stand-alone entry, copying the material that was inside

*equivariant differential topology*.

- Discussion Type
- discussion topicequivariant differential topology
- Category Latest Changes
- Started by Urs
- Comments 13
- Last comment by Urs
- Last Active 6 days ago

- Discussion Type
- discussion topicDiers spectrum
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 3
- Last comment by Dmitri Pavlov
- Last Active 6 days ago

- Discussion Type
- discussion topicthick subcategory
- Category Latest Changes
- Started by nLab edit announcer
- Comments 10
- Last comment by Mike Shulman
- Last Active 6 days ago

- Discussion Type
- discussion topiccompact Lie group
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicinvariant differential form
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicHaar integral
- Category Latest Changes
- Started by nLab edit announcer
- Comments 11
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicnormalizer
- Category Latest Changes
- Started by Urs
- Comments 13
- Last comment by Urs
- Last Active 7 days ago

I have edited and rearranged just a little at

*normalizer*, in order to clarify a little more.

- Discussion Type
- discussion topiccoset
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

added pointer to:

- Glen Bredon, Section I.4 of:
*Introduction to compact transformation groups*, Academic Press 1972 (ISBN 9780080873596, pdf)

- Glen Bredon, Section I.4 of:

- Discussion Type
- discussion topichomogeneous space
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

added pointer to:

- Glen Bredon, Section I.4 of:
*Introduction to compact transformation groups*, Academic Press 1972 (ISBN 9780080873596, pdf)

- Glen Bredon, Section I.4 of:

- Discussion Type
- discussion topicorbit type
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicstabilizer group
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

added pointer to:

- Glen Bredon, Section I.2 of:
*Introduction to compact transformation groups*, Academic Press 1972 (ISBN 9780080873596, pdf)

- Glen Bredon, Section I.2 of:

- Discussion Type
- discussion topicequivariant
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

added pointer to:

- Glen Bredon, Section I.2 of:
*Introduction to compact transformation groups*, Academic Press 1972 (ISBN 9780080873596, pdf)

- Glen Bredon, Section I.2 of:

- Discussion Type
- discussion topicIntroduction to compact transformation groups
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicLie group
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active 7 days ago

tried to bring the entry Lie group a bit into shape: added plenty of sections and cross links to other nLab material. But there is still much that deserves to be done.

- Discussion Type
- discussion topicclassical Lie group
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

added pointer to:

- Glen Bredon, Section 0.2 of:
*Introduction to compact transformation groups*, Academic Press 1972 (ISBN 9780080873596, pdf)

- Glen Bredon, Section 0.2 of:

- Discussion Type
- discussion topicMaria Smizanska
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

brief

`category:people`

-entry for hyperlinking references at*B-meson*and*flavour anomaly*

- Discussion Type
- discussion topicZdenek Dolezal
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 7 days ago

brief

`category:people`

-entry for hyperlinking references at*B-meson*and*flavour anomaly*

- Discussion Type
- discussion topicB meson
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 7 days ago

- Discussion Type
- discussion topicdifferential K-theory
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Apr 7th 2021

I have expanded the list of references at

*differential K-theory*with a few comments thrown in.

- Discussion Type
- discussion topictranscendental syntax
- Category Latest Changes
- Started by nLab edit announcer
- Comments 4
- Last comment by Boris Eng
- Last Active Apr 7th 2021

- Discussion Type
- discussion topicSpin(11,3)
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active Apr 7th 2021

I am giving this group a stub entry just to have a decent place to record today’s

- Kirill Krasnov,
*$Spin(11,3)$, particles and octonions*(arXiv:2104.01786)

For this entry not to be all too lonely I made Spin(10,2) point to D=12 supergravity, for the moment. In the long run all this derserves to be expanded on, clearly.

- Kirill Krasnov,

- Discussion Type
- discussion topicfixed point space
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Apr 7th 2021

- Discussion Type
- discussion topicHofer's geometry
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 7th 2021

I have fixed the title of

- Helmut Hofer,
*On the topological properties of symplectic maps*, Proceedings of the Royal Society of Edinburgh. Section A: Mathematics, Volume 115 Issue 1-2, 1990 (doi:10.1017/S0308210500024549)

and added the DOI

- Helmut Hofer,

- Discussion Type
- discussion topicpolyfold
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Apr 7th 2021

added pointer to

- Helmut Hofer,
*Polyfolds and Fredholm Theory*, Oxford University Press (2017) (doi:10.1093/oso/9780198784913.003.0004)

and tried to clean up the list of references a little, such as ordering it by date of appearance, and correcting the spelling to

*Katrin Wehrheim*. There is more room for improvement here, but I’ll leave it at that.- Helmut Hofer,

- Discussion Type
- discussion topicbicategory of fractions
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 10
- Last comment by DavidRoberts
- Last Active Apr 7th 2021

- Discussion Type
- discussion topicorbifold groupoid
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 4
- Last comment by Urs
- Last Active Apr 7th 2021

- Discussion Type
- discussion topicétendue
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 1
- Last comment by Dmitri Pavlov
- Last Active Apr 7th 2021

- Discussion Type
- discussion topiccellular approximation theorem
- Category Latest Changes
- Started by Tim_Porter
- Comments 10
- Last comment by Dmitri Pavlov
- Last Active Apr 6th 2021

Someone anonymous has raised the question of subdivision at cellular approximation theorem. I do not have a source here in which I can check this. Can anyone else check up?

- Discussion Type
- discussion topicAdmir Greljo
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 6th 2021

brief

`category:people`

-entry for hyperlinking references at*flavour anomaly*and at*leptoquark*

- Discussion Type
- discussion topicPeter Stangl
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 6th 2021

brief

`category:people`

-entry for hyperlinking references at*flavour anomaly*

- Discussion Type
- discussion topiccategory of G-sets
- Category Latest Changes
- Started by nLab edit announcer
- Comments 3
- Last comment by Urs
- Last Active Apr 6th 2021

- Discussion Type
- discussion topicD=14 supersymmetry
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by David_Corfield
- Last Active Apr 6th 2021

Entry to go with D=12 supergravity and bosonic M-theory, but for the moment just to record references

- Discussion Type
- discussion topicexceptional spinors and division algebras -- table
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Apr 6th 2021

I needed a table

*exceptional spinors and division algebras – table*, and so I have created one and included it into the relevant entries

- Discussion Type
- discussion topicSpin(9,1)
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 6th 2021

- Discussion Type
- discussion topicSpin(10,2)
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 6th 2021

a stub, just for completeness, to go alongside Spin(11,3) and D=12 supergravity

- Discussion Type
- discussion topicinfinity-stack homotopically
- Category Latest Changes
- Started by David_Corfield
- Comments 5
- Last comment by Urs
- Last Active Apr 6th 2021

- Discussion Type
- discussion topicdifferential equation
- Category Latest Changes
- Started by Urs
- Comments 14
- Last comment by Urs
- Last Active Apr 6th 2021

created differential equation just to link to Lawvere's two articles on that.

Peering through the Lawverian prose, say on page 10 of Toposes of laws of motion I seem to see the shadow of a theory of integration in smooth toposes.

The extension along the inclusion of an infinitesimal object into another object considered there is of the same general nature as the extensins along the inclusion of infnitesimal into all paths that I consider at integration of oo-Lie algebroid valued differential forms.

I mean, no big deal, just something I noticed.

- Discussion Type
- discussion topicHomePage
- Category Latest Changes
- Started by Urs
- Comments 67
- Last comment by Urs
- Last Active Apr 6th 2021

I have added at

*HomePage*in the section*Discussion*a new sentence with a new link:If you do contribute to the nLab, you are strongly encouraged to similarly drop a short note there about what you have done – or maybe just about what you plan to do or even what you would like others to do. See Welcome to the nForum (nlabmeta) for more information.

I had completly forgotton about that page

*Welcome to the nForum (nlabmeta)*. I re-doscivered it only after my recent related comment here.

- Discussion Type
- discussion topiccategory theory
- Category Latest Changes
- Started by Eric
- Comments 72
- Last comment by Urs
- Last Active Apr 6th 2021

I removed some spam on category theory.

- Discussion Type
- discussion topicspin group
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Apr 6th 2021

added a section “Examples” with the table of low dimensional rotation groups (which somehow had been omitted here, all along)

- Discussion Type
- discussion topicinitial Θ-data
- Category Latest Changes
- Started by Richard Williamson
- Comments 43
- Last comment by DavidRoberts
- Last Active Apr 6th 2021

Am making a start on trying to understand something of Mochizuki’s IUTT papers. I do not hold out any promises on how far I am going to get, or how long it is going to take me! Even this very first definition is going to me a long time, I think, as I intend to try to fill out all details. All help will be appreciated!

- Discussion Type
- discussion topicLudwig Faddeev
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 1
- Last comment by Dmitri Pavlov
- Last Active Apr 5th 2021

Renamed to match the spelling used by Faddeev in his English papers.

Linked to Dmitri Faddeev.