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- Discussion Type
- discussion topica few stubs (vertex coloring, bipartite graph, virtual knot theory)
- Category Latest Changes
- Started by Noam_Zeilberger
- Comments 1
- Last comment by Noam_Zeilberger
- Last Active Sep 21st 2015

I created a few stub pages recently: a couple on Saturday for vertex coloring and bipartite graph (thanks to Thomas Holder for a correction and the references), and today the stubbiest of stubs for virtual knot theory.

- Discussion Type
- discussion topictrigonometry
- Category Latest Changes
- Started by zskoda
- Comments 1
- Last comment by zskoda
- Last Active Sep 15th 2015

New stub trigonometry.

- Discussion Type
- discussion topicfree probability
- Category Latest Changes
- Started by zskoda
- Comments 1
- Last comment by zskoda
- Last Active Sep 10th 2015

Stub for free probability to record some references.

- Discussion Type
- discussion topiccoend and Kan extension
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Sep 9th 2015

I have added to Kan extension in the section on the pointwise coend formula some elementary illustrative discussion of the case of left Kan extension of presheaves, that some readers might benefit from at this point, see this example.

- Discussion Type
- discussion topicWaldhausen
- Category Latest Changes
- Started by Tim_Porter
- Comments 1
- Last comment by Tim_Porter
- Last Active Sep 6th 2015

Someone (at Waldhausen category changed axiom C3) as it was incorrect. The new version still looked wrong, and I have changed it further. (Could someone check that I have got it right now!)

- Discussion Type
- discussion topiccomplete topological space
- Category Latest Changes
- Started by Mike Shulman
- Comments 30
- Last comment by TobyBartels
- Last Active Aug 31st 2015

I don’t like the name of the page complete topological space; it seems to suggest that a property of “completeness” can be defined for topological spaces, when in fact one needs additional structure on a topological space (like a metric, a uniformity, or at least a Cauchy structure) in order to say what “complete” means. Since the notion of Cauchy space seems to be the maximum generality in which the notion applies, how about renaming the page to “complete Cauchy space”?

- Discussion Type
- discussion topicCocomm Coalg
- Category Latest Changes
- Started by Todd_Trimble
- Comments 4
- Last comment by DavidRoberts
- Last Active Aug 31st 2015

I have been adding some material to Cocomm Coalg. I’m not sure where I first read that this category is extensive, and hope that a relatively painless proof of that can be produced.

- Discussion Type
- discussion topicNew article: [[underlying topological space]]
- Category Latest Changes
- Started by TobyBartels
- Comments 4
- Last comment by Todd_Trimble
- Last Active Aug 30th 2015

It's really the reflection of topological spaces within a larger category, but usually people think of it as underlying: underlying topological space.

- Discussion Type
- discussion topictopos of algebras over a monad
- Category Latest Changes
- Started by Urs
- Comments 19
- Last comment by spitters
- Last Active Aug 29th 2015

have created topos of algebras over a monad

- Discussion Type
- discussion topicTrivial subalgebras
- Category Latest Changes
- Started by TobyBartels
- Comments 3
- Last comment by TobyBartels
- Last Active Aug 27th 2015

A bit of trivial algebra at trivial subalgebra.

- Discussion Type
- discussion topicConstructive algebra
- Category Latest Changes
- Started by TobyBartels
- Comments 9
- Last comment by TobyBartels
- Last Active Aug 26th 2015

I wrote a constructive definition of simple group, which brought up other issues, so I wrote antisubalgebra and strongly extensional function.

- Discussion Type
- discussion topic[[mathematicscontents]]
- Category Latest Changes
- Started by TobyBartels
- Comments 2
- Last comment by TobyBartels
- Last Active Aug 24th 2015

Apparently, the page mathematicscontents, despite being included in a number of other pages, has not existed since shortly after it was spammed slightly more than a year ago. So before blanking a spam page, make sure that it has no history! I have restored it now (although it took a little bit to figure out what it had been called, since it doesn't follow the standard naming format for included contents).

- Discussion Type
- discussion topicsyntactic category
- Category Latest Changes
- Started by Mike Shulman
- Comments 10
- Last comment by Colin Zwanziger
- Last Active Aug 21st 2015

I added a hatnote to syntactic category remarking on an alternative usage of the phrase.

- Discussion Type
- discussion topicregular and coherent categories
- Category Latest Changes
- Started by Mike Shulman
- Comments 2
- Last comment by TobyBartels
- Last Active Aug 21st 2015

Did some cleaning up and adding to regular category and coherent category, and asked a terminological question at the latter.

- Discussion Type
- discussion topicEric Sharpe
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Aug 21st 2015

I have expanded the text in the entry on

*Eric Sharpe*a little, and added a list of publications. The recent one- Eric Sharpe,
*Notes on generalized global symmetries in QFT*(arXiv:1508.04770)

reviews and expands on aspects of higher groups/stacks/gerbes in QFT and string theory in a style that ought to appeal to people with physics background.

- Eric Sharpe,

- Discussion Type
- discussion topicdefinition of regular monomorphism
- Category Latest Changes
- Started by JonasFrey
- Comments 9
- Last comment by JonasFrey
- Last Active Aug 19th 2015

I came across a non-standard definition of “regular monomorphism” in Cassidy/Hébert/Kelly’s “Reflective subcategories, localizations and factorizations systems.” and added a note to the nlab page. They define a regular mono to be a joint equalizer of an arbitrary family of parallel pairs. This is more general than the usual definition, and forces the class of regular monos to be closed under arbitrary intersections.

I think that in a well powered category with small products the definition should coincide with the usual one, and in coregular categories both should coincide with “strong mono”.

Any comments? Does this definition of regular mono appear anywhere else? Or is there maybe an alternative term for it?

- Discussion Type
- discussion topicsuperextensive site
- Category Latest Changes
- Started by Mike Shulman
- Comments 10
- Last comment by Mike Shulman
- Last Active Aug 14th 2015

Wrote superextensive site, with a purported proof that sheafification for the single covers does preserve extensive-sheaves in that case.

- Discussion Type
- discussion topiccalibrated manifold
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Aug 13th 2015

Have started some minimum at

*calibration*.

- Discussion Type
- discussion topicNew page: [[Hurewicz fibration]]
- Category Latest Changes
- Started by TobyBartels
- Comments 15
- Last comment by Richard Williamson
- Last Active Aug 12th 2015

Zoran just wrote Hurewicz fibration.

- Discussion Type
- discussion topicThe World in Eleven Dimensions
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Aug 11th 2015

have started a category:reference entry on

- Mike Duff,
*The World in Eleven Dimensions: Supgergravity, Supermembranes and M-theory*, IoP 1999

and have added pointers to it from relevant entries

- Mike Duff,

- Discussion Type
- discussion topicAtiyah class
- Category Latest Changes
- Started by zskoda
- Comments 1
- Last comment by zskoda
- Last Active Aug 9th 2015

I added redirets Atiyah sequence, Atiyah class, Atiyah algebroid to Atiyah Lie algebroid. Maybe we want to have Lie algebroid aspect (concentrating on bracket) and the cohomological/derived category aspect (cohomology class of the exact sequence of modules) separate in fuiture, but now the material is still too small. I added a number of interesting references and a sentence on the class.

- Discussion Type
- discussion topiccelestial sphere
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Todd_Trimble
- Last Active Aug 6th 2015

created

*celestial sphere*

- Discussion Type
- discussion topicgrand unified theory
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Aug 5th 2015

added a few items to the References section at

*GUT*, both on theoretical background as well as on fits to the latest experimental data. According to these, the $SO(10)$-model seems to be well alive, susy or not.

- Discussion Type
- discussion topichigher Poisson structure
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Aug 4th 2015

I have created a new entry

meant as a disambiguation page for the various different kinds of definitions that exists. Presently it points to the entries

that already provide dedicated discussion of special defintiions. In addtion it lists references that have further proposals for defintion which don’t at the moment however have dedicated $n$Lab pages associated with them.

- Discussion Type
- discussion topiccumulative hierarchy
- Category Latest Changes
- Started by Todd_Trimble
- Comments 10
- Last comment by DavidRoberts
- Last Active Aug 3rd 2015

Wrote cumulative hierarchy, and edited some at ZFC (idea section, reference, related articles).

- Discussion Type
- discussion topichigher parallell transport
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active Aug 3rd 2015

started stub for higher parallel transport (but no definition yet, just examples and pointers)

- Discussion Type
- discussion topicn-vector spaces
- Category Latest Changes
- Started by domenico_fiorenza
- Comments 25
- Last comment by Urs
- Last Active Aug 1st 2015

I just noticed we miss an entry n-vector space. I’d like to start it, but I only have a very vague idea, recursively implementing the notion of Baez-Crans 2-vector space. something like: an $n$-vector space is an $(n-1)$-category of modules over a $(n-1)$-Vect enriched symmetric monoidal $(n-1)$-category.

how far is this from the correct notion?

- Discussion Type
- discussion topicRoland Schwänzl
- Category Latest Changes
- Started by Tim_Porter
- Comments 2
- Last comment by RodMcGuire
- Last Active Jul 29th 2015

I was going to add a stub page on Roland Schwänzl, to avoid grey links, and linking to the Wikipedia page, but looking at that I am very confused (and my German is too rusty!) That page seems to be about two people or did Roland Schwänzl actually do things on UNIX etc as well as working with Vogt? My search did not even give me the genealogy page for him, (although I now have found it).. Can anyone help?

- Discussion Type
- discussion topicM-theory super Lie algebra
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active Jul 26th 2015

The nLab presently gives me an application error when trying to open anything, so I’ll record some things here.

The following needs to be added to the References-section of the entry

*M-theory super Lie algebra*:The M-theory super Lie algebra as first considered in

Jan-Willem van Holten, Antoine Van Proeyen,

*$N=1$ supersymmetry algebras in $d=2,3,4 \,mod\, 8$*J.Phys. A15, 3763 (1982).Paul Townsend,

*p-Brane Democracy*(arXiv:hep-th/9507048)

Discussion of its formulation in terms of octonions (see also at

*division algebra and supersymmetry*) includes- A. Anastasiou, L. Borsten, Michael Duff, L. J. Hughes, S. Nagy,
*An octonionic formulation of the M-theory algebra*(arXiv:1402.4649)

- Discussion Type
- discussion topicParmenides dialogue
- Category Latest Changes
- Started by Tim_Porter
- Comments 23
- Last comment by Leebloomquist
- Last Active Jul 25th 2015

I fixed a link that was not working. (The brackets were interfering with the link address.) see here

- Discussion Type
- discussion topicHoàng Xuân Sính and 2-group
- Category Latest Changes
- Started by DavidRoberts
- Comments 4
- Last comment by Tim_Porter
- Last Active Jul 23rd 2015

I created Hoàng Xuân Sính as a result of recent G+ discussion, and David Eppstein creating an English Wikipedia page for her. There is now a link to that page at 2-group and a(n updated) link to her thesis.

- Discussion Type
- discussion topicUK researchers
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by zskoda
- Last Active Jul 21st 2015

for those who check the logs and are wondering: I went through a fairly long list of category:people-entries on people based in and around London, updating affiliation links, references and related $n$Lab entries.

- Discussion Type
- discussion topicWeyl quantization
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by zskoda
- Last Active Jul 21st 2015

discovered that we already had a stub on

*Weyl quantization*. Cross-linked a bit and added the following reference on Weyl quantization of Chern-Simons theory (also to*quantization of 3d Chern-Simons theory*):Jørgen Andersen,

*Deformation quantization and geometric quantization of abelian moduli spaces*, Commun. Math. Phys., 255 (2005), 727–745Razvan Gelca, Alejandro Uribe,

*The Weyl quantization and the quantum group quantization of the moduli space of flat SU(2)-connections on the torus are the same*, Commun.Math.Phys. 233 (2003) 493-512 (arXiv:math-ph/0201059)Razvan Gelca, Alejandro Uribe,

*From classical theta functions to topological quantum field theory*(arXiv:1006.3252, slides pdf)Razvan Gelca, Alejandro Uribe,

*Quantum mechanics and non-abelian theta functions for the gauge group $SU(2)$*(arXiv:1007.2010)

- Discussion Type
- discussion topicGrothendieck
- Category Latest Changes
- Started by Tim_Porter
- Comments 7
- Last comment by Noam_Zeilberger
- Last Active Jul 21st 2015

I have added a new link to the page on Grothendieck. There is a good new article on a CNRS site.

- Discussion Type
- discussion topicWeyl n-algebra
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 20th 2015

given the concept of

*Heisenberg Lie n-algebra*, there is an evident definition of*Weyl n-algebra*: its universal enveloping E-n algebra.I noted that down for reference at

*Weyl n-algebra*. In the process I noticed that Markarian proposed a different definition just a few months back

- Discussion Type
- discussion topicMaximal partial function
- Category Latest Changes
- Started by TobyBartels
- Comments 7
- Last comment by Mike Shulman
- Last Active Jul 20th 2015

Just some obvious stuff at maximal partial function to satisfy some links.

- Discussion Type
- discussion topicmoduli space of Calabi-Yau spaces
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 19th 2015

started a stub for

*moduli space of Calabi-Yau spaces*. Nothing really there yet, except some references and some cross-links.

- Discussion Type
- discussion topictheta function
- Category Latest Changes
- Started by Urs
- Comments 12
- Last comment by Urs
- Last Active Jul 19th 2015

I tried to start an entry theta function, but it’s hard to tell for me if anything of it has been saved. The $n$Lab is too busy doing something else than serving pages.

- Discussion Type
- discussion topicpieces-have-points is initial resolution
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 18th 2015

I have added the statement of lemmas 4.1, 4.2 of Menni-Lawvere to

*cohesive topos*here and to*points-to-pieces transform*here.

- Discussion Type
- discussion topictheta functions - contents
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 18th 2015

I am starting a table of contents

*theta functions - contents*and am including it as a “floating table of contents” into relevant entries

- Discussion Type
- discussion topic(x, y) ⊙ (u, v) = (xu + 2yv, xv + yu)
- Category Latest Changes
- Started by Tim_Porter
- Comments 5
- Last comment by Tim_Porter
- Last Active Jul 18th 2015

The entry entitled (x, y) ⊙ (u, v) = (xu + 2yv, xv + yu) has been started. Is it Spam? or does that definition mean something useful to the nPOV.

- Discussion Type
- discussion topicfunctional equation
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 17th 2015

made explicit in the Idea section of

*functional equation*the statement that the functional equation of a zeta function is the incarnation under Mellin transform of the automorphy of the automorphic form that it comes from

- Discussion Type
- discussion topicautomorphic L-function
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Jul 17th 2015

gave

*automorphic L-function*a minimum of an Idea-section, presently it reads as follows:

An

*automorphic L-function*$L_\pi$ is an L-function built from an automorphic representation $\pi$, in nonabelian generalization of how a Dirichlet L-function $L_\chi$ is associated to a Dirichlet character $\chi$ (which is an automorphic form on the (abelian) idele group).In analogy to how Artin reciprocity implies that to every 1-dimensional Galois representation $\sigma$ there is a Dirichlet character $\chi$ such that the Artin L-function $L_\sigma$ equals the Dirichlet L-function $L_\chi$, so the conjectured Langlands correspondence says that to every $n$-dimensional Galois representation $\sigma$ there is an automorphic representation $\pi$ such that the automorphic L-function $L_\pi$ equals the Artin L-function $L_\sigma$.

- Discussion Type
- discussion topicholomorphic block
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jul 16th 2015

stub for

*holomorphic block*, for the moment just to record two references

- Discussion Type
- discussion topicprequantum line bundle
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Jul 16th 2015

gave prequantum line bundle a little entry of its own

- Discussion Type
- discussion topicEngeler's lemma
- Category Latest Changes
- Started by Todd_Trimble
- Comments 1
- Last comment by Todd_Trimble
- Last Active Jul 13th 2015

Wrote Engeler’s lemma, something I hadn’t heard of until recently.

- Discussion Type
- discussion topicHilbert basis theorem
- Category Latest Changes
- Started by DavidRoberts
- Comments 2
- Last comment by Todd_Trimble
- Last Active Jul 9th 2015

I added a few comments to Hilbert basis theorem about related work by Gordon and Noether (chronologically, on either side of Hilbert’s work).

- Discussion Type
- discussion topicleft-determined model categories
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 6
- Last comment by Mike Shulman
- Last Active Jul 9th 2015

I created the article left-determined model category.

- Discussion Type
- discussion topicprime ideal theorem
- Category Latest Changes
- Started by Todd_Trimble
- Comments 2
- Last comment by DavidRoberts
- Last Active Jul 9th 2015

I had begun adding to prime ideal theorem (en route adding to compactness theorem), but have decided to stop midstream because it looks as though much more general results are known, which I’d need to read up on it before writing further.

One thing I’ll mention now is that the surmise (due to Toby?) that UF is equivalent to the prime ideal theorem for rigs seems to be known and subsumed under these general results. Banaschewski’s name comes up as one having a key lattice-theoretic insight into this topic: “Every nontrivial distributive complete lattice with a compact top element contains a prime element.”

- Discussion Type
- discussion topicfinite field
- Category Latest Changes
- Started by Todd_Trimble
- Comments 2
- Last comment by IngoBlechschmidt
- Last Active Jul 7th 2015

The entry finite field was looking a little sad, so I added to it.

- Discussion Type
- discussion topicsplitting field
- Category Latest Changes
- Started by Todd_Trimble
- Comments 7
- Last comment by DavidRoberts
- Last Active Jul 7th 2015

Created splitting field.

- Discussion Type
- discussion topic(infinity,1)-natural transformation
- Category Latest Changes
- Started by Mike Shulman
- Comments 3
- Last comment by Mike Shulman
- Last Active Jul 6th 2015

Do we have a page about natural transformations between $(\infty,1)$-categories? I wanted to add a link to this paper (working today on catching up with the arXiv…) but I couldn’t find where to put it.

- Discussion Type
- discussion topicbinormal topological space
- Category Latest Changes
- Started by zskoda
- Comments 1
- Last comment by zskoda
- Last Active Jul 6th 2015

New entry binormal topological space.

- Discussion Type
- discussion topicpower operation
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by David_Corfield
- Last Active Jul 3rd 2015

am starting

*power operation*, but nothing there yet except references

- Discussion Type
- discussion topicétale fundamental-, Chevalley fundamental-, Galois-groups
- Category Latest Changes
- Started by Urs
- Comments 20
- Last comment by David_Corfield
- Last Active Jul 1st 2015

We have a bit of a mess of closely related entries related to étale homotopy groups which existed more or less in parallel without seeming to know much of each other. I have tried to do some minimum of cross-linking and cleaning up, but this needs more attention.

There is more even, there is

*Grothendieck’s Galois theory*and what not. (Maybe we need to wait until somebody gives a course on this and uses the occasion to clean it all up and harmonize it.)

- Discussion Type
- discussion topicexponent of a group
- Category Latest Changes
- Started by Todd_Trimble
- Comments 4
- Last comment by SridharRamesh
- Last Active Jun 30th 2015

Created exponent of a group.

- Discussion Type
- discussion topicUFD
- Category Latest Changes
- Started by Todd_Trimble
- Comments 1
- Last comment by Todd_Trimble
- Last Active Jun 30th 2015

I added more material to unique factorization domain.

- Discussion Type
- discussion topictopological map/embedded graph
- Category Latest Changes
- Started by Noam_Zeilberger
- Comments 1
- Last comment by Noam_Zeilberger
- Last Active Jun 30th 2015

I’ve slowly been trying to improve the article topological map since this thread. I just added a small note on embedded graphs versus abstract graphs, motivated by Bruce Bartlett’s interesting recent post at the n-café.

- Discussion Type
- discussion topicCauchy's theorem
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Todd_Trimble
- Last Active Jun 30th 2015

- Discussion Type
- discussion topicfalling factorial
- Category Latest Changes
- Started by Noam_Zeilberger
- Comments 5
- Last comment by Noam_Zeilberger
- Last Active Jun 26th 2015

I created a stub for falling factorial, mainly to record the simple fact I learned yesterday that it counts the number of injections between two finite sets.