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

• Recording the result from Triantafillou 82, characterizing injective/projective objects in diagrams of vector spaces over (the opposite of) the orbit category.

(The degreewise ingredients in the rational model for topological G-spaces)

• I took the liberty of incorporating material from Andre Joyal's latest message to the CatTheory mailing list into the entry dagger-category:

created sections

• Replace “infinity” with “∞”.

Mark John Hopkins

• As I’ve already said elsewhere, I’ve been working on this entry and trying to give a precise definition based on my hunches of what guys like Steenrod really meant by “a convenient category of topological spaces”. (I must immediately admit that I’ve never read his paper with that title. Of course, he meant specifically compactly generated Hausdorff spaces, but nowadays I think we can argue more generally.)

I also said elsewhere that my proposed axiom on closed and open subspaces might be up for discussion. The other axioms maybe not so much: dropping any of them would seem to be a deal-breaker for what an algebraic topologist might consider “convenient”. Or so I think.

• a stub, to record some references

• Peter Hilton, Urs Stammbach, Section I.9 in: A course in homological algebra, Springer-Verlag, New York, 1971, Graduate Texts in Mathematics, Vol. 4 (doi, pdf)
• I edited The Joy of Cats to link to metacategory and to disambiguate quasicategory, as twice now someone on MO has used the term ’quasicategory’ to talk about (very) large categories. This way, if people find the book using the nLab page they are forewarned.

I also edited quasicategory to move the terminological warning up to the idea section where it is immediately visible, rather than in the second section, below the definition.

• I think the line between the two types of Kan extension (weak versus pointwise) is drawn at the wrong place. Am I missing something?

• starting something. Not done yet, but need to save

• stub entry, for the moment just to record the reference

• for completeness

• Page created, but author did not leave any comments.

• for completeness

• for completeness

• just for completeness

• made explicit that for a normal subgroup $N \subset G$ its “Weyl group” in the sense of $W_H G \coloneqq (N_G H)/H$ coincides with the plain quotient group $G/N$.

• stub for Chern character

just the blind definition so far, to be expanded later

• Added some simple instances of dual theories.