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    • Todd,

      when you see this here and have a minute, would you mind having a look at monoidal category to see if you can remove the query-box discussion there and maybe replace it by some crisp statement?


    • The filtered limit is typo of filtered colimit


      diff, v4, current

    • a stub entry, for the moment just to make the link work

      v1, current

    • throw out scratch notes from a bajillion years ago

      Blake C. Stacey

      diff, v14, current

    • I’ve made a few changes at flat module since I wanted to know what one was and the nLab page simply confused me further. It seemed to be saying that a module over a ring/algebra AA is flat if tensoring with AA is a flat functor. That seemed absurd so I changed it. The observation “everything happens for a reason” was a little curt so once I’d worked out what it meant I expanded it a bit and put in the analogy to bases. It wasn’t clear from the way that it was phrased whether this condition was due to Wraith and Blass or the fact that it can be put in a more general context. Lastly, the last sentence was originally in the same paragraph as the penultimate sentence where it didn’t seem to fit (or was at best ambiguous) and it also claimed that the module could be non-unital which seemed a little odd.

      If an expert could kindly check that I’ve done no lasting damage to the page, I’d be grateful.

    • considerably expanded the entry strict 2-group.

      • Apart from adding an introductory discussion, and expanding the list of examples, in particular by adding that of automorphism 2-groups ...

      • ... I in particular give the detailed translation prescription for how to encode a 2-group by a crossed module at In terms of crossed modules

      This is to eventually serve as a supplement to the discussion at nonabelian group cohomology. So I spent some energy on disentangling the four different (though isomorphic) ways a crossed module gives rise to a 2-group (following my article with David Roberts).

    • Created page, copying material from the one on David Roberts’ web.

      v1, current

    • A bare beginning, will fill in more later.

      v1, current

    • Added a stub for this journal, as a place to link to category theoretic papers published there, which can be difficult to find for those unfamiliar with Gallica.

      v1, current

    • I edited

      to make it clear that this tensor product only works for finite abelian categories, which are what we get from looking at finite-dimensional representations of finite-dimensional associative algebras. It’s all very finite… and over fields, too, at least in the treatment by Pavel Etingof, Shlomo Gelaki, Dmitri Nikshych, Victor Ostrik, which is all I have access to now. It would be nice to see this kind of thing done more generally. The slides by Ignacio López Franco, linked on this page, are a hint of how to do it.

    • just a bare minimum to make the link work

      v1, current

    • a minimum, just for completeness and to make broken links work

      v1, current

    • a brief table of entries related to nn-spheres, to be !include-ed into related entries, for ease of hyperlinking

      v1, current

    • for completeness, and to make some broken links work

      v1, current

    • expanded on metrization theorems, added section “Related concepts”.

      diff, v2, current

    • added the pointers to the combinatorial proofs of the fiberwise detection of acyclicity of Kan fibrations, currently discussed on the AlgTop list, to the nLab here.

    • at vector bundle I have spelled out the proof that for XX paracompact Hausdorff then the restrictions of vector bundles over X×[0,1]X \times [0,1] to X×{0}X \times \{0\} and X×{1}X \times \{1\} are isomorphic.

      It’s just following Hatcher, but I wanted to give full detail to the argument of what is now this lemma.

    • brief category:people-entry for hyperlinking references

      v1, current

    • brief category:peopleentry for hyperlinking references

      v1, current

    • I fixed a broken link to Guy Moore’s lectures

      diff, v9, current

    • I reorganized linearly distributive category by moving the long block of history down to the bottom, adding an “Idea” section and a description of how **-autonomous categories give rise to linearly distributive ones and linearly distributive ones give rise to polycategories. I also cross-linked the page better with polycategory and star-autonomous category.

    • The article wrote “locally ∞-presentable (∞,1)-category” when I’m sure κ\kappa-presentable was meant.

      diff, v6, current

    • 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.

    • Added very explicitely what is a confluent rewriting system.

      diff, v5, current

    • Added reference to the conjectured higher topological topos

      diff, v22, current

    • As discussed on the nforum in the thread here, the definition of the antisymmetric tensor power was incorrect.

      diff, v20, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • Add a stub for this concept. I will add more details shortly.

      v1, current

    • have expanded the single sentence at differential geometry to something like a paragraph, indicating how differential geometry is the “higher geometry modeled on the pre-geometry 𝒢=CartSp\mathcal{G} = CartSp

    • brief category:people-entry for hyperlinking references

      v1, current