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- Discussion Type
- discussion topicMatthew Burke
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 2 days ago

- Discussion Type
- discussion topicKristine Bauer
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 2 days ago

- Discussion Type
- discussion topicmanifold with boundary
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active 2 days ago

added the statement (now this prop) that smooth manifolds with boundary are fully faithful in diffeological spaces, with pointer to Igresias-Zemmour 13, section 4.16.

Will add the same to

*diffeological space*.

- Discussion Type
- discussion topicskyrmion
- Category Latest Changes
- Started by Urs
- Comments 36
- Last comment by Urs
- Last Active 2 days ago

- Discussion Type
- discussion topicsubdivision
- Category Latest Changes
- Started by Urs
- Comments 28
- Last comment by DavidRoberts
- Last Active 2 days ago

Todd had created subdivision.

I interlinked that with the entry Kan fibrant replacement, where the subdivision $nerve \circ Face$ appears.

- Discussion Type
- discussion topichomotopy group of a spectrum
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topicCantor-Schroeder-Bernstein theorem
- Category Latest Changes
- Started by Mike Shulman
- Comments 7
- Last comment by Daniel Luckhardt
- Last Active 3 days ago

- Discussion Type
- discussion topicring spectrum
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active 3 days ago

noticed that the Idea-section at

*ring spectrum*didn’t at all address the evident subtlety here. Have expanded now to make this clear.

- Discussion Type
- discussion topicHopf invariant
- Category Latest Changes
- Started by Urs
- Comments 24
- Last comment by Urs
- Last Active 3 days ago

I have been making trivial edits (adding references, basic statements, cross-links ) to

*Hopf invariant*and a bunch of related entries, such as*Kervaire invariant*,*Hopf invariant one problem*,*Arf-Kervaire invariant problem*,*normed division algebra*.

- Discussion Type
- discussion topicconnective cover
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active 3 days ago

created a minimum at

*connective cover*, just for completeness

- Discussion Type
- discussion topicunder category
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active 3 days ago

copied over, from

*overcategory*, statement and proof of computing limits in undercategories

- Discussion Type
- discussion topiccohomology operation
- Category Latest Changes
- Started by Urs
- Comments 11
- Last comment by Urs
- Last Active 3 days ago

added a little bit of content to

*cohomology operation*

- Discussion Type
- discussion topicMichael Boardman
- Category Latest Changes
- Started by Tim_Porter
- Comments 2
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topicHandbook of Algebraic Topology
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topicmonoidal category with diagonals
- Category Latest Changes
- Started by DavidRoberts
- Comments 10
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topicPostnikov system
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active 3 days ago

I have added pointer to the second of Postnikov’s original articles on the matter:

- M. M. Postnikov,
*Issledovaniya po gomotopičeskoĭ teorii nepreryvnyh otobraženiĭ. I. Algebraičeskaya teoriya sistem. II. Naturalʹnaya sistema i gomotopičeskiĭ tip*. (Russian) $[$_Investigations in homotopy theory of continuous mappings. I. The algebraic theory of systems. II. The natural system and homotopy type._$]$ Trudy Mat. Inst. Steklov. no. 46. Izdat. Akad. Nauk SSSR, Moscow, 1955. (mathnet:tm1182)

Is there any linkable online trace of Postnikov’s first article:

- M. M. Postnikov,
*Determination of the homology groups of a space by means of the homotopy invariants*, Doklady Akad. Nauk SSSR (N.S.) 76: 359–362 (1951)

?

- M. M. Postnikov,

- Discussion Type
- discussion topicsmash-monoidal diagonals -- section
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 3 days ago

a bare sub-section, meant to be

`!include`

-ed into the Examples-sections of relevant entries, such as at*monoidal category with diagonals*,*smash product*and*cup product*

- Discussion Type
- discussion topicsymmetric smash product of spectra
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 days ago

fixed notation in the second formula in the proof of this Prop.:

(The adjoined base point $(-)_+$ to the symmetric group factor was previously displayed below the formula beneath the underbrace below the symmetric group symbol that it really belonged to. And in the second line of that formula under the brace, the corresponding $(-)_+$ had been missing.)

- Discussion Type
- discussion topicAndrew Stacey
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 days ago

- Discussion Type
- discussion topicWilliam Mycroft
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 days ago

brief

`category:people`

-entry for hyperlinking references at*cohomology opperation*

- Discussion Type
- discussion topicnonabelian cohomology
- Category Latest Changes
- Started by nLab edit announcer
- Comments 12
- Last comment by Urs
- Last Active 4 days ago

- Discussion Type
- discussion topicDavid Copeland Johnson
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 days ago

brief

`category:people`

-entry for hyperlinking references at*Johnson-Wilson spectrum*,*cohomology operation*and elsewhere

- Discussion Type
- discussion topicHopf algebra
- Category Latest Changes
- Started by Urs
- Comments 17
- Last comment by Urs
- Last Active 4 days ago

added to the Properties-section at Hopf algebra a brief remark on their interpretation as 3-vector spaces.

- Discussion Type
- discussion topicW. Stephen Wilson
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 4 days ago

- Discussion Type
- discussion topicbound state
- Category Latest Changes
- Started by Urs
- Comments 3
- Last comment by Urs
- Last Active 4 days ago

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

- Discussion Type
- discussion topicPaul Hoyer
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 4 days ago

brief

`category:people`

-entry for hyperlinking refetences ar*bound state*

- Discussion Type
- discussion topiclinear logic
- Category Latest Changes
- Started by Mike Shulman
- Comments 15
- Last comment by Urs
- Last Active 4 days ago

The cut rule for linear logic used to be stated as

If $\Gamma \vdash A$ and $A \vdash \Delta$, then $\Gamma \vdash \Delta$.

I don’t think this is general enough, so I corrected it to

If $\Gamma \vdash A, \Phi$ and $\Psi,A \vdash \Delta$, then $\Psi,\Gamma \vdash \Delta,\Phi$.

- Discussion Type
- discussion topicPetri net
- Category Latest Changes
- Started by Tim_Porter
- Comments 14
- Last comment by Mike Shulman
- Last Active 4 days ago

I have created a stub for this at Petri net. I hope to develop the links with higher dimensional automata and also with linear logic.

- Discussion Type
- discussion topicMUFr
- Category Latest Changes
- Started by Urs
- Comments 7
- Last comment by Urs
- Last Active 4 days ago