Not signed in (Sign In)

A discussion forum about contributions to the nLab wiki and related areas of mathematics, physics, and philosophy.

Want to take part in these discussions? Sign in if you have an account, or apply for one below

2-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry bundle bundles calculus categories category category-theory chern-weil-theory cohesion cohesive-homotopy-type-theory cohomology colimits combinatorics complex complex-geometry computable-mathematics computer-science constructive cosmology deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry digraphs duality elliptic-cohomology enriched fibration finite foundations functional-analysis functor galois-theory gauge-theory gebra geometric-quantization geometry graph graphs gravity group group-theory harmonic-analysis higher higher-algebra higher-category-theory higher-differential-geometry higher-geometry higher-lie-theory higher-topos-theory homological homological-algebra homology homotopy homotopy-theory homotopy-type-theory index-theory infinity integration integration-theory itex k-theory lie-theory limits linear linear-algebra locale localization logic mathematics measure measure-theory modal modal-logic model model-category-theory monads monoidal monoidal-category-theory morphism motives motivic-cohomology nlab noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pages pasting philosophy physics planar pro-object probability probability-theory quantization quantum quantum-field quantum-field-theory quantum-mechanics quantum-physics quantum-theory question representation representation-theory riemannian-geometry scheme schemes set set-theory sheaf simplicial space spin-geometry stable-homotopy-theory string string-theory superalgebra supergeometry svg symplectic-geometry synthetic-differential-geometry terminology theory topology topos topos-theory tqft type type-theory universal variational-calculus

Vanilla 1.1.10 is a product of Lussumo. More Information: Documentation, Community Support.

If you want to take part in these discussions either sign in now (if you have an account), apply for one now (if you don't).

- Discussion Type
- discussion topicdiffeological space
- Category Latest Changes
- Started by Urs
- Comments 23
- Last comment by Urs
- Last Active 1 hour ago

seeing Eric create diffeology I became annoyed by the poor state that the entry diffeological space was in. So I spent some minutes expanding and editing it. Still far from perfect, but a step in the right direction, I think.

(One day I should add details on how the various sites in use are equivalent to using CartSp)

- Discussion Type
- discussion topicfully faithful (infinity,1)-functor
- Category Latest Changes
- Started by Hurkyl
- Comments 7
- Last comment by Hurkyl
- Last Active 2 hours ago

- Discussion Type
- discussion topicPedro Boavida de Brito
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 2 hours ago

brief

`category:people`

-entry for hyperlinking references at*manifold calculus*and at*shape via cohesive path ∞-groupoid*

- Discussion Type
- discussion topicmanifold calculus
- Category Latest Changes
- Started by David_Corfield
- Comments 2
- Last comment by Urs
- Last Active 2 hours ago

Added to references:

Brian Munson,

*Introduction to the manifold calculus of Goodwillie-Weiss*(arXiv:1005.1698)Thomas Willwacher,

*Configuration spaces of points and real Goodwillie-Weiss calculus*, talk at Isaac Newton Institute, 2018.

- Discussion Type
- discussion topicshape via cohesive path ∞-groupoid
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 2 hours ago

I have added pointer to the arXiv copy to the item

- Daniel Berwick-Evans, Pedro Boavida de Brito, Dmitri Pavlov,
*Classifying spaces of infinity-sheaves*(arXiv:1912.10544)

- Daniel Berwick-Evans, Pedro Boavida de Brito, Dmitri Pavlov,

- Discussion Type
- discussion topicTullio Regge
- Category Latest Changes
- Started by David_Corfield
- Comments 1
- Last comment by David_Corfield
- Last Active 3 hours ago

Added the reference:

- Leonardo Castellani, Anna Ceresole, Riccardo D’Auria, Pietro Fré (eds.):
*Tullio Regge: An Eclectic Genius*, World Scientific 2019 (doi:10.1142/11643)

- Leonardo Castellani, Anna Ceresole, Riccardo D’Auria, Pietro Fré (eds.):

- Discussion Type
- discussion topicclassifying topos
- Category Latest Changes
- Started by Urs
- Comments 51
- Last comment by Thomas Holder
- Last Active 3 hours ago

edited classifying topos and added three bits to it. They are each marked with a comment "check the following".

This is in reaction to a discussion Mike and I are having with Richard Williamson by email.

- Discussion Type
- discussion topicthunk-force category
- Category Latest Changes
- Started by maxsnew
- Comments 22
- Last comment by Urs
- Last Active 4 hours ago

Started thunk-force category.

- Discussion Type
- discussion topicDiff
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 hours ago

made this a disambiguation page (previously it was the name of the entry now called

*SmoothManifolds*)

- Discussion Type
- discussion topicSmoothManifolds
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 4 hours ago

I have started working on Diff: added a subsection with discussion of its properties as a site.

Added statement and proof of the fact that

$Sh(Diff)$ is a cohesive topos (direct consequence of the

*comparison lemma*)$Sh_{(\infty,1)}(Diff)$ is a cohesive (infinity,1)-topos (easy with some lemmas from the literature, but not immediate (I think))

- Discussion Type
- discussion topicAnna Ceresole
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 5 hours ago

- Discussion Type
- discussion topicD'Auria-Fre formulation of supergravity
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active 5 hours ago

crated D'Auria-Fre formulation of supergravity

there is a blog entry to go with this here

- Discussion Type
- discussion topicquasi-Borel space
- Category Latest Changes
- Started by Sam Staton
- Comments 3
- Last comment by PaoloPerrone
- Last Active 10 hours ago

- Discussion Type
- discussion topicIsbell duality
- Category Latest Changes
- Started by spitters
- Comments 33
- Last comment by Todd_Trimble
- Last Active 16 hours ago

http://ncatlab.org/nlab/show/Isbell+duality

Suggests that Stone, Gelfand, … duality are special cases of the adjunction between CoPresheaves and Presheaves. A similar question is raised here. http://mathoverflow.net/questions/84641/theme-of-isbell-duality

However, this paper http://www.emis.ams.org/journals/TAC/volumes/20/15/20-15.pdf

seems to use another definition. Could someone please clarify?

- Discussion Type
- discussion topicdialgebra
- Category Latest Changes
- Started by varkor
- Comments 5
- Last comment by varkor
- Last Active 22 hours ago

The page on inductive-inductive types refers to dialgebras without specifying them. Having a short page as some sort of reference is helpful.

- Discussion Type
- discussion topicsimplicial skeleton
- Category Latest Changes
- Started by mattecapu
- Comments 1
- Last comment by mattecapu
- Last Active 1 day ago

- Discussion Type
- discussion topicQuasi-Borel spaces
- Category Latest Changes
- Started by PaoloPerrone
- Comments 6
- Last comment by PaoloPerrone
- Last Active 1 day ago

- Discussion Type
- discussion topicn-truncated object of an (infinity,1)-category
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 1 day ago

- Discussion Type
- discussion topichyperstonean space
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 1
- Last comment by Dmitri Pavlov
- Last Active 1 day ago

- Discussion Type
- discussion topiccomplete category
- Category Latest Changes
- Started by maxsnew
- Comments 4
- Last comment by Dmitri Pavlov
- Last Active 1 day ago

- Discussion Type
- discussion topic(eso and full, faithful) factorization system
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 1 day ago

Just noticed that when this page is shown in a Google search, the link from the Google page does not work. It seems that the “+” sign that used to be in the entry title gets interpreted as a whitespace.

Therefore I am now changing the page name, replacing “+” by “and”. This should fix the problem, once Google picks up the change.

- Discussion Type
- discussion topicbijective on objects functor
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 1 day ago

- Discussion Type
- discussion topicproperties of functors -- contents
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 1 day ago

- Discussion Type
- discussion topicessentially surjective and full functor
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 1 day ago

am giving this its own page, to make it easier to find and to hyperlink – the content is mostly taken from remarks that were scattered at

*n-connected object of an (infinity,1)-topos*and*(eso and full, faithful) factorization system*

- Discussion Type
- discussion topicinternalization
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Taro
- Last Active 1 day ago

started to add to internalization a list of links to examples. Probably we have much more.

- Discussion Type
- discussion topiccompact space
- Category Latest Changes
- Started by Todd_Trimble
- Comments 86
- Last comment by Mike Shulman
- Last Active 1 day ago

As an outcome of recent discussion at Math Overflow here, Mike Shulman suggested some nLab pages where comparisons of different definitions of compactness are rigorously established. I have created one such page: compactness and stable closure. (The importance and significance of the stable closure condition should be brought out better.)

- Discussion Type
- discussion topicmodal homotopy type theory
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active 1 day ago

copied over the homotopy-theoretic references from

*modal type theory*to here.

- Discussion Type
- discussion topicflavour anomaly
- Category Latest Changes
- Started by Urs
- Comments 133
- Last comment by Urs
- Last Active 1 day ago

- Discussion Type
- discussion topicNiels Tuning
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 1 day ago

brief

`category:people`

-page for hyperlinking references at*flavour anomaly*and at*LHCb experiment*

- Discussion Type
- discussion topicHopf-Galois extension
- Category Latest Changes
- Started by David_Corfield
- Comments 1
- Last comment by David_Corfield
- Last Active 2 days ago

Added a reference

- John Rognes,
*Galois extensions of structured ring spectra/Stably dualizable groups*, Memoires of the American Mathematical Society, 192(898), 2008, partly available as (pdf)

- John Rognes,