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 categorical 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 foundation foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry 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 history homological homological-algebra homotopy homotopy-theory homotopy-type-theory index-theory integration integration-theory k-theory lie lie-theory limit limits linear linear-algebra locale localization logic mathematics measure-theory modal modal-logic model model-category-theory monad 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 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 topicArun Kumar Pati
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicno-cloning theorem
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Feb 23rd 2023

created a stub for

*no-cloning theorem*.For the moment what I wanted to highlight is that under the identification of linear logic as quantum logic it is this theorem which is the “linearity” of the logic.

- Discussion Type
- discussion topiclogic gate
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicQWIRE
- Category Latest Changes
- Started by Urs
- Comments 6
- Last comment by Urs
- Last Active Feb 23rd 2023

one more in the list of quantum programming languages

- Discussion Type
- discussion topicdirected topological space
- Category Latest Changes
- Started by nLab edit announcer
- Comments 5
- Last comment by Christoph Dorn
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicnerve
- Category Latest Changes
- Started by Mike Shulman
- Comments 33
- Last comment by BryceClarke
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicJuan Polo Gomez
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicMalcolm G. Boshier
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicLuigi Amico
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicatomtronics
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 23rd 2023

- Discussion Type
- discussion topicdefinitional equality
- Category Latest Changes
- Started by nLab edit announcer
- Comments 3
- Last comment by Urs
- Last Active Feb 22nd 2023

- Discussion Type
- discussion topicJán Pulmann
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by nLab edit announcer
- Last Active Feb 22nd 2023

brief

`category:people`

-entry for hyperlinking references at*non-abelian T-duality*and elsewhere

- Discussion Type
- discussion topicBHK interpretation
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by Urs
- Last Active Feb 22nd 2023

fixed the pointer to:

- L. E. J. Brouwer,
*Points and Spaces*, Canadian Journal of Mathematics**6**(1954) 1-17 [doi:10.4153/CJM-1954-001-9]

- L. E. J. Brouwer,

- Discussion Type
- discussion topicDirk van Dalen
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 22nd 2023

- Discussion Type
- discussion topicconstructive mathematics
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active Feb 22nd 2023

I made “constructive logic” redirect to here (“constructive mathematics”) instead of to “intuitionistic mathematics”, as it used to

- Discussion Type
- discussion topicconstructive analysis
- Category Latest Changes
- Started by Urs
- Comments 15
- Last comment by Urs
- Last Active Feb 22nd 2023

added some references on

*constructive analysis*here.

- Discussion Type
- discussion topicconcretification
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 7
- Last comment by Dmitri Pavlov
- Last Active Feb 21st 2023

- Discussion Type
- discussion topicGoodwillie calculus
- Category Latest Changes
- Started by Urs
- Comments 41
- Last comment by Tom Mainiero
- Last Active Feb 21st 2023

stub for Goodwillie calculus

- Discussion Type
- discussion topicorthogonal calculus
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 21st 2023

edit publication data for:

- David Barnes, Rosona Eldred,
*Comparing the orthogonal and homotopy functor calculi*, Journal of Pure and Applied Algebra**220**11 (2016) 3650-3675 [arXiv:1505.05458, doi:10.1016/j.jpaa.2016.05.005]

- David Barnes, Rosona Eldred,

- Discussion Type
- discussion topictotalization
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Urs
- Last Active Feb 21st 2023

stub for totalization

- Discussion Type
- discussion topicPeano arithmetic
- Category Latest Changes
- Started by Todd_Trimble
- Comments 6
- Last comment by Urs
- Last Active Feb 21st 2023

I added some material to Peano arithmetic and Robinson arithmetic. At the latter, I replaced the word “fragment” (which sounds off to my ears – actually Wikipedia talks about thisterm a little) with “weakening”.

Still some links to be inserted.

- Discussion Type
- discussion topicabstract Stone duality
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 21st 2023

- Discussion Type
- discussion topicDedekind cut
- Category Latest Changes
- Started by IngoBlechschmidt
- Comments 7
- Last comment by Urs
- Last Active Feb 21st 2023

Added to

*Dedekind cut*a short remark on the $\neg\neg$-stability of membership in the lower resp. the upper set of a Dedekind cut.

- Discussion Type
- discussion topicconformal block
- Category Latest Changes
- Started by zskoda
- Comments 6
- Last comment by Urs
- Last Active Feb 21st 2023

conformal block and Vassily Gorbounov. Update at Imma Galvez.

- Discussion Type
- discussion topicBernhard Riemann
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 1
- Last comment by Dmitri Pavlov
- Last Active Feb 21st 2023

- Discussion Type
- discussion topicStokes theorem
- Category Latest Changes
- Started by Urs
- Comments 24
- Last comment by Dmitri Pavlov
- Last Active Feb 21st 2023

created Stokes theorem

- Discussion Type
- discussion topicphotonic crystal
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicJanusz E. Jacak
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicLaughlin wavefunction
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicfactorization system
- Category Latest Changes
- Started by nLab edit announcer
- Comments 3
- Last comment by anuyts
- Last Active Feb 20th 2023

I have added references to two (overlapping) papers which list elementary examples of factorization systems associated with the notions of: compact, discrete, connected, and totally disconnected spaces, dense image, induced topology, and separation axioms; finite groups being nilpotent, solvable, torsion-free, p-groups, and prime-to-p groups; injective and projective modules; injective, surjective, and split homomorphisms.

Anonymous

- Discussion Type
- discussion topicalgebraic weak factorization system
- Category Latest Changes
- Started by BryceClarke
- Comments 4
- Last comment by anuyts
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicorthogonal factorization system
- Category Latest Changes
- Started by Urs
- Comments 23
- Last comment by anuyts
- Last Active Feb 20th 2023

I have added to

*orthogonal factorization system*in the Definition-section three equivalent explicit formulations of the definition;

in the Properties-section the statement of the cancellability property.

Wanted to add more (and to add the proofs). But have to quit now. Maybe later.

- Discussion Type
- discussion topicweak factorization system
- Category Latest Changes
- Started by Urs
- Comments 13
- Last comment by anuyts
- Last Active Feb 20th 2023

I have been polishing and expanding the entry

*weak factorization system*:gave it an Idea-section;

gave the definitions numbered environments and full details;

spelled out the proof of the closure properties in full detail.

Regarding notation: I decided to use as generic name for a weak factorization system:

not $(L,R)$, as used to be used in the entry (for that’s already my preferred generic choice for pairs of adjoint functors on the $n$Lab, and for discussion of Quillen adjunctions the notation conventions would clash);

not $(E,M)$ or the like, since that gives no hint as to what is meant (running into an “$E$” in the middle of some discussion, the reader is always at risk of having to browse back to figure out which class is meant);

but… $(Proj, Inj)$, for that is nicely indicating what is meant.

- Discussion Type
- discussion topicBrayton Gray
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicpropositions as types
- Category Latest Changes
- Started by JonAwbrey
- Comments 19
- Last comment by Urs
- Last Active Feb 20th 2023

I started reworking a quasi-periodic study of mine on propositions as types that introduces the factors of "proof hints" and "untyped terms" into the analogy.

**Update .**This material is now at propositions as types in combinatory algebra.

- Discussion Type
- discussion topicstructure
- Category Latest Changes
- Started by Urs
- Comments 33
- Last comment by Urs
- Last Active Feb 20th 2023

After discussion here I have changed the organization of the entry

*structure*and then expanded a bit by adding an Idea-section and a bit more here and there.(The previous organization of the entry instead made it look like

*structure in model theory*is a concept on par with that discussed at*stuff, structure, property*. But instead, the latter axiomatizes the general notion of “structure on something” as such, whereas the former is an*example*of a structure on something (namely an “$L$-structure on a set”). The new version aims to reflect this properly.)

- Discussion Type
- discussion topicAnalysis Situs
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topichomotopy theory FAQ
- Category Latest Changes
- Started by Dmitri Pavlov
- Comments 25
- Last comment by Urs
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicrelevant monad
- Category Latest Changes
- Started by nLab edit announcer
- Comments 2
- Last comment by J-B Vienney
- Last Active Feb 20th 2023

- Discussion Type
- discussion topicKesha Hietala
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicMichael Hicks
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicShih-Han Hung
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicAnanda Roy
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicDaniel Loss
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicDavid P. DiVincenzo
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicspin resonance qbits -- references
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Feb 19th 2023

a bare list of references, to be

`!include`

-ed into the References-sections of relevant entries (such as at*qbit*,*quantum computation*,*nuclear magnetic resonance*), for ease of synchronizing

- Discussion Type
- discussion topicadjoint functor
- Category Latest Changes
- Started by Urs
- Comments 67
- Last comment by Urs
- Last Active Feb 19th 2023

added at adjoint functor

more details in the section In terms of universal arrows;

a bit in the section Examples

- Discussion Type
- discussion topicconcurrency theory
- Category Latest Changes
- Started by nLab edit announcer
- Comments 2
- Last comment by David_Corfield
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicn-truncation modality
- Category Latest Changes
- Started by nLab edit announcer
- Comments 2
- Last comment by Urs
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicdeformation theory of sheaves
- Category Latest Changes
- Started by nLab edit announcer
- Comments 1
- Last comment by nLab edit announcer
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicintuitionistic mathematics
- Category Latest Changes
- Started by TobyBartels
- Comments 35
- Last comment by Urs
- Last Active Feb 19th 2023

I finally wrote this: intuitionistic mathematics.

- Discussion Type
- discussion topicsequential limit
- Category Latest Changes
- Started by Hurkyl
- Comments 2
- Last comment by Urs
- Last Active Feb 19th 2023

Included the condition on sequential (co)limits that the indexing ordinal should be nonzero, which I presume to be the correct convention. (e.g. based on the description they are a special case of filtered colimits)

- Discussion Type
- discussion topiclinear lambda-calculus
- Category Latest Changes
- Started by J-B Vienney
- Comments 1
- Last comment by J-B Vienney
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicSeely isomorphism
- Category Latest Changes
- Started by J-B Vienney
- Comments 1
- Last comment by J-B Vienney
- Last Active Feb 19th 2023

- Discussion Type
- discussion topicMealy morphism
- Category Latest Changes
- Started by nLab edit announcer
- Comments 11
- Last comment by Urs
- Last Active Feb 18th 2023

- Discussion Type
- discussion topicnatural deduction
- Category Latest Changes
- Started by nLab edit announcer
- Comments 12
- Last comment by Urs
- Last Active Feb 18th 2023

- Discussion Type
- discussion topicformal logic
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Feb 18th 2023

I keep feeling the need to point to an entry named

*formal logic*. None of the existing entries seems to quite deserve to be where this link should be redirecting to. So I created a page*formal logic*with just some pointers to pages that the reader*might*expect behind this term.Just so that I can use that link for the time being.

- Discussion Type
- discussion topicintuitionistic logic
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active Feb 18th 2023

I have added the Tarski reference to intuitionistic logic and internal logic

- Discussion Type
- discussion topiclogical connective
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active Feb 18th 2023

`!include`

-ed the*logic symbols – table*into this old stub entry

- Discussion Type
- discussion topicWhitehead theorem
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active Feb 18th 2023

created Whitehead theorem, including its (oo,1)-topos version

in that context I also created hypercomplete (infinity,1)-topos. maybe that should be merged eventually with hypercompletion.