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 book bundles calculus categories category category-theory chern-weil-theory cohesion cohesive-homotopy-theory 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 differential-topology digraphs duality elliptic-cohomology enriched fibration finite foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry goodwillie-calculus graph graphs gravity grothendieck 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 homotopy homotopy-theory homotopy-type-theory index-theory integration integration-theory k-theory kan lie lie-theory limits linear linear-algebra locale localization logic manifolds mathematics measure-theory 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 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 science 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 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 topicstring field theory
- Category Latest Changes
- Started by Urs
- Comments 18
- Last comment by Urs
- Last Active Jan 28th 2020

I have started adding references to

*string field theory*, in particular those by Jim Stasheff et al. on the role of L-infinity algebra and A-infinity algebra. Maybe I find time later to add more details.

- Discussion Type
- discussion topicframed manifold
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by David_Corfield
- Last Active Jan 28th 2020

added a bit to

*framed manifold*

- Discussion Type
- discussion topicDuff interview at M-Theory-Mathematics 2020
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by Urs
- Last Active Jan 28th 2020

- Discussion Type
- discussion topicPaolo Perrone
- Category Latest Changes
- Started by PaoloPerrone
- Comments 2
- Last comment by Urs
- Last Active Jan 27th 2020

- Discussion Type
- discussion topicuniversal Vassiliev invariant
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Jan 27th 2020

- Discussion Type
- discussion topicgroup
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Todd_Trimble
- Last Active Jan 27th 2020

reformatted the entry group a little, expanded the Examples-section a little and then pasted in the group-related “counterexamples” from counterexamples in algebra. Mainly to indicate how I think this latter entry should eventually be used to improve the entries that it refers to.

- Discussion Type
- discussion topicCantor-Schroeder-Bernstein theorem
- Category Latest Changes
- Started by Mike Shulman
- Comments 6
- Last comment by DavidRoberts
- Last Active Jan 27th 2020

- Discussion Type
- discussion topichydrogen line
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Jan 26th 2020

Detection of the 21cm hydrogen absorption line expected in the CMB has been claimed now. Such a detection is thought to have implications for observational cosmology comparable in relevance to those of the recent gravitational wave detection. I have collected some original articles and reviews here in an otherwise empty entry

*hydrogen line*

- Discussion Type
- discussion topicconvex function
- Category Latest Changes
- Started by Todd_Trimble
- Comments 4
- Last comment by TobyBartels
- Last Active Jan 26th 2020

Expanded the formerly stubby article convex function, giving examples, properties, etc.

- Discussion Type
- discussion topicbosonic M-theory
- Category Latest Changes
- Started by David_Corfield
- Comments 9
- Last comment by Urs
- Last Active Jan 26th 2020

- Discussion Type
- discussion topicJackiw-Teitelboim gravity
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Jan 26th 2020

- Discussion Type
- discussion topicEntropy
- Category Latest Changes
- Started by TobyBartels
- Comments 45
- Last comment by DavidRoberts
- Last Active Jan 26th 2020

I have written a disordered article lacking information. No, wait! I mean, I have written an article on a measure of disorder and lack of information: entropy.

This is from a very mathematical perspective, but I have also tried to indicate how this connects to the physical notion of entropy. (This is something that I would like to understand better!)

- Discussion Type
- discussion topicopen/closed string duality
- Category Latest Changes
- Started by nLab edit announcer
- Comments 6
- Last comment by Urs
- Last Active Jan 25th 2020

- Discussion Type
- discussion topicprototype CLF
- Category Latest Changes
- Started by atmacen
- Comments 46
- Last comment by atmacen
- Last Active Jan 24th 2020

- Discussion Type
- discussion topiclarge 1/N limit
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active Jan 24th 2020

- Discussion Type
- discussion topicfour-colour theorem
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jan 24th 2020

added this pointer (hat tip to David C. here):

On the logical equivalence between the four-colour theorem and a statement about transition from the small N limit to the large N limit for Lie algebra weight systems on Jacobi diagrams via the ’t Hooft double line construction:

- Dror Bar-Natan,
*Lie Algebras and the Four Color Theorem*, Combinatorica 17-1(1997) 43–52 (arXiv:q-alg/9606016, doi:10.1007/BF01196130)

- Dror Bar-Natan,

- Discussion Type
- discussion topiccolor charge
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Jan 24th 2020

- Discussion Type
- discussion topicQCD and strongly coupled gauge theories - challenges and perspectives
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jan 24th 2020

- Discussion Type
- discussion topicpion
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jan 24th 2020

added pointer to today’s

- Domenec Espriu, Alisa Katanaeva,
*Effects of bulk symmetry breaking on AdS/QCD predictions*(arXiv:2001.08723)

- Domenec Espriu, Alisa Katanaeva,

- Discussion Type
- discussion topicmonads of probability, measures, and valuations
- Category Latest Changes
- Started by PaoloPerrone
- Comments 7
- Last comment by PaoloPerrone
- Last Active Jan 23rd 2020

- Discussion Type
- discussion topicMaterial set theory
- Category Latest Changes
- Started by TobyBartels
- Comments 91
- Last comment by atmacen
- Last Active Jan 23rd 2020

I have reorganised set theory and spun off material set theory.

- Discussion Type
- discussion topiclens (in computer science)
- Category Latest Changes
- Started by David_Corfield
- Comments 8
- Last comment by David_Corfield
- Last Active Jan 23rd 2020

- Discussion Type
- discussion topicquantization of Yang-Mills theory
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Urs
- Last Active Jan 23rd 2020

I keep having the need to point to something like mass gap problem. So now I created a stub for it, just so that the links works. Has to be expanded, clearly.

- Discussion Type
- discussion topicoptics
- Category Latest Changes
- Started by David_Corfield
- Comments 4
- Last comment by David_Corfield
- Last Active Jan 23rd 2020

- Discussion Type
- discussion topiclight-cone gauge quantization
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Jan 23rd 2020

created a bare minimum at

*light-cone gauge quantization*, just so as to be able to sensibly link to it from elsewhere

- Discussion Type
- discussion topicRandall-Sundrum model
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Jan 22nd 2020

- Discussion Type
- discussion topicbicategory of relations
- Category Latest Changes
- Started by Todd_Trimble
- Comments 15
- Last comment by nLab edit announcer
- Last Active Jan 22nd 2020

More propositions and stuff entered at bicategory of relations.

- Discussion Type
- discussion topiccomoving time
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jan 22nd 2020

- Discussion Type
- discussion topicflavour (particle physics)
- Category Latest Changes
- Started by Urs
- Comments 18
- Last comment by Urs
- Last Active Jan 22nd 2020

- Discussion Type
- discussion topicnucleosynthesis
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Jan 22nd 2020