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

• I added a bunch of things to connected space: stuff on the path components functor, an example of a countable connected Hausdorff space, and the observation that the quasi-components functor is left adjoint to the discrete space functor $Set \to Top$ (Wikipedia reports that the connected components functor is left adjoint to the discrete space functor, but that’s wrong).

This bit about quasi-components functor had never occurred to me before, although it seems to be true. I’m having difficulty getting much information on this functor. For example, does it preserve finite products? I don’t know, but I doubt it. Does anyone reading this know?

• Andre Joyal just created on the nLab an entry titled CatLab

• I am compiling character tables of various groups. For ease of including into related entries (e.g. for isomorphic groups) I’ll give them their own little entries

• Starting a stub.

• K-cohomology is a strangely organised page with 5 sections identically named. There supposed to be some difference from K-theory

• I have created brief stubs for cyclotomic field and anti-cyclotomic field. No real content there for the moment, just so as to make cross-links work and have a place to record references.

I suppose what I am really looking for regarding discussion here in another thread is a concept of anti-cyclotomic spectrum.

• some minimum

• needed to point to ring of integers of a number field. The term used to redirect just to integers. I have split it off now with a minimum of content. Have to rush off now.

• Hello all, I was wondering if one or two of you would be able to find the time to see if you think that the arguments on the following page, on my personal web, are correct? There are so many sharp minds amongst the readership here, that I’m sure if there is an error, one of you will make short work of finding it!

Observations on prime divisors of odd integers in a range (richardwilliamson)

With these kinds of elementary arguments, everything has to be exactly right; the entire argument is likely to collapse if the smallest detail is wrong. Thus, though I have checked the argument several times myself, including after having slept on it, it is eminently possible that I have overlooked something, so do read with a critical eye :-).

I am also thinking of making a little page, for completeness, on Bertrand’s postulate, on the main nLab, which I can link to in my argument. Would this be OK (I ask because I don’t know any category theoretic point of view on it at all)?

Any feedback will be greatly appreciated!

• There was an “Idea” at Bridgeland stability condition. I added the sections Definition, Key Results, and Examples. I also added a reference for the last key result listed. I should probably fill in some related stubs like t-structure or classical notions of stability.

• a small entry for a finite group, really an unintended spin-off of compiling the character table of 2O (see discussion there)

• I am compiling character tables of various groups. For ease of including into related entries (e.g. for isomorphic groups) I’ll give them their own little entries

• have added to Topos in the section on limits of toposes the description of the pullback of toposes by pushout of their sites of definition.

• I am compiling character tables of various groups. For ease of including into related entries (e.g. for isomorphic groups) I’ll give them their own little entries

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

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

• the entry braid group said what a braid is, but forgot to say what the braid group is; I added in a sentence, right at the beginning (and fixed some other minor things).

• created an entry modal type theory; tried to collect pointers I could find to articles which discuss the interpretation of modalities in terms of (co)monads. I was expecting to find much less, but there are a whole lot of articles discussing this. Also cross-linked with monad (in computer science).

• First attempt at a major revision of permutation that gives equal weight to the view of permutations-as-linear-orders, hoping that this article will eventually contain some discussion of the operad of permutations and of permutation patterns.

• created at internal logic an Examples-subsection and spelled out at Internal logic in Set how by turning the abstract-nonsense crank on the topos Set, one does reproduce the standard logic.

• added the statement (here) that of all finite subgroups of $SU(2)$, $Q_8$ is a proper subgroup of the three exceptional ones.

Checking normality of this subgroup, I noticed that there is an issue with another item of the entry here, where it used to claim that a finite group is Hamiltonian precisely of it “contains a copy of $Q_8$”. But this can’t be, can it. I changed it to saying that every Hamiltonian group contains $Q_8$ as a subgroup, which I suppose is what was meant.

[edit: I see now that the statement that I changed back to was made already by Thomas Holder in rev 3, while the statement I removed was made by Thomas in rev 4. Thomas, if you see this, please let me know. ]

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

Matthew Weaver

• I found myself writing permutation (since I had linked to it) and realised that I could even redirect symmetric group there (which has been linked to for some time).

Pretty stubby now.