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    • I just see that in this entry it said

      Classically, 1 was also counted as a prime number, …

      If this is really true, it would be good to see a historic reference. But I’d rather the entry wouldn’t push this, since it seems misguided and, judging from web discussion one sees, is a tar pit for laymen to fall into.

      The sentence continued with

      …[[ the number 1 is ]] too prime to be prime.

      and that does seem like a nice point to make. So I have edited the entry to now read as follows, but please everyone feel invited to have a go at it:

      A prime number is a natural number which cannot be written as a product of two smaller numbers, hence a natural number greater than 1, which is divisible only by 1 and by itself.

      This means that every natural number n∈ℕn \in \mathbb{N} is, up to re-ordering of factors, uniquely expressed as a product of a tuple of prime numbers:

      n=2 n 13 n 25 n 37 n 411 n 5⋯ n \;=\; 2^{n_1} 3^{n_2} 5^{n_3} 7^{n_4} 11^{ n_5 } \cdots

      This is called the prime factorization of nn.

      Notice that while the number 1∈ℕ1 \in \mathbb{N} is, clearly, only divisible by one and by itself, hence might look like it deserves to be counted as a prime number, too, this would break the uniqueness of this prime factorization. In view of the general phenomenon in classifications in mathematics of objects being too simple to be simple one might say that 1 is “too prime to be prime”.

      diff, v13, current

    • broken link for Kitaev-Kong paper, uploaded pdf instead

      diff, v9, current

    • Just a stub explaining the ramifications of common usages of the (rather undefined) term.

      v1, current

    • a stub entry, for the moment just in order to satisfy links

      v1, current

    • Added characterization of κ\kappa-compact objects in λ\lambda-accessible categories.

      diff, v63, current

    • Creating a stand-along entry for this, so that one can link to it.

      We used to have (and still have, of course) a subsection of that title “Internal direct sum” here at direct sum.

      I have copied that material over, but pre-fixed it by the form of the definition usually found in algebra texts.

      v1, current

    • filling out the missing knottheory stuff a bit

      Vinithezip

      v1, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • 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

      • V. G. Drinfeld, Quasi-Hopf algebras and Knizhnik-Zanolodchikov equations, Acad. Sci. Ukrainian SSR, Institute for Theoretical Physics, Preprint ITP-89-43B (Kiev 1989) pdf

      diff, v9, current

      P.S. erased later, the reference is not directly appropriate for this entry.

    • Adding table of contents and a link to the Wikipedia article

      Anonymouse

      diff, v5, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • brief category:people-entry for hyperlinking references

      v1, current

    • I changed back the name of the page to coherent state. Though it is usually considered in quantum mechanics, and the name is still correct, as a specialist in the area of coherent states, I have almost never seen the phrase “coherent quantum state” written out in mathematical physics, so I would prefer to have this long unusual name as a redirect only. Of course, we often talk about the coherence of quantum states. But this is about a general feature of coherence, like in optics. The specific states in mathematical physics which, among other features, have such coherence properties are usually called squeezed coherent states, and the coherent states of these entry are even more specific than those. I am about to add a couple of new references, so I came across the page again.

      diff, v15, current

    • tried to bring the entry Lie group a bit into shape: added plenty of sections and cross links to other nLab material. But there is still much that deserves to be done.

    • Starting a page for indexing systems

      Natalie Stewart

      v1, current

    • Starting stub on the Heine-Cantor theorem

      Anonymouse

      v1, current

    • found a mathoverflow question where people in the answers are talking about σ\sigma-topological groups and sets equipped with a σ\sigma-topology, so decided to create an article on such objects.

      v1, current

    • I’m interested in editing Mac Lane’s proof of the coherence theorem for monoidal categories, as I recently went through all the gory details myself and wrote it up. I was wondering if anybody has any thoughts on what should be left alone with regard to any future changes. Many people clearly put in a lot of work into the page, but it looks like people got busy and it hasn’t been updated in a while.

      I think the first few paragraphs are fine, but I think the rest is a bit wordy, it could be more formal, and notation could be changed (very slightly) to be less clunky. I specifically want to make the current document more formal (e.g., saying “Definition: blah blah”), include some nice diagrams, change the notation (e.g., to avoid using double primes, to avoid denoting a monoidal category as B since I think the letter M pedagogically makes more sense), and complete the incomplete entries at the bottom. I’m not really sure if anyone would be against such changes, hence my inquiry.

    • created traced monoidal category with a bare minimum

      I would have sworn that we already had an entry on that, but it seems we didn’t. If I somehow missed it , let me know and we need to fix things then.

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