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    • Epstein zeta function, just recording the definition and the two classical references by Kronecker and Siegel. Nominally, this is the page 13133 of the nnLab ;)

    • I am starting Wick algebra. So far I have an Idea-section, references, and a discussion of the finite dimensional case, showing how the traditional “normal ordered Wick product” is the Moyal star product of an almost-Kähler vector space.

    • at S-matrix and elsewhere is reference to the “causal order“-relation, the relation saying that for a pair (S 1,S 2)(S_1,S_2) of subsets of a spacetime, S 1S_1 does not intersect the past of S 2S_2, or equivalently that S 2S_2 does not intersect the future of S 1S_1.

      (Following a suggestion by Arnold Neumaier, a neat suggestive notation for this is S 1∨∧S 2S_1 {\vee\!\!\!\wedge} S_2, which I have been implementing now at S-matrix.)

      I am starting to give this concept its own entry, currently titled “causal order”; but what’s good terminology?

      This relation ∨∧{\vee\!\!\!\wedge} is not really an ordering, since it is not transitive. It would seem tempting to say “causal relation”, but googling for this term shows that has an different established meaning.

    • I have added to star product some basic facts, and their proofs, for the case of star products induced from constant rank-2 tensors ω\omega on Euclidean spaces: the definition, proof of the associativity, proof that shifts of ω\omega by symmetric contributions are algebra isomorphisms.

    • I gave Dickey bracket its own entry (just a brief Idea-section and references)

      (the term “Dickey bracket” used to redirect to conserved current, where however it was mentioned only in the references. Now it should be easier to discern what the pointer is pointing to. Of course the entry remains a stub nonetheless.)

    • Added to Hadamard distribution the standard expression for the standard choice on Minkowski spacetime, as well as statement and proof of its contour integral representation (here)

    • I have included at geometric quantization the definition of quantum operators associated with a given function on phase space in geometric quantization. Then I decided to split it off to dedicated entry quantum operator.

    • added to spectrum with G-action brief paragraphs “Relation to genuine G-spectra”, and “relation to equivariant cohomology”.

      Both would deserve to be expanded much more, but it’s a start.

    • At positive type we have

      In denotational semantics, positive types behave well with respect to “call-by-value” and other eager evaluation strategies.

      and dually at negative type we have

      In denotational semantics, negative types behave well with respect to “call-by-name” and other lazy evaluation strategies.

      This doesn’t seem right to me; don’t evaluation strategies belong to operational semantics?

    • I created an entry called (infinity,1)-Yoneda extension.

      Currently the point of this entry is to present one specific presentation by model category means of what should more abstractly be an (oo,1)-version of the standard Yoneda extension. The statement is (supposed to be) a simple consequence of the proposition recalled at Quillen bifunctor.

      I started preparing this entry on my personal web, but then thought that this kind of material should be on the main nLab. Let me know if you disagree.

      I put a standout-box cautioning the reader that this is stuff I dreamed up. But even in as far as the statement so far given is right, I would like the entry to be understood as something in search of a bigger and more abstract picture.

    • Made a stub for admissible rule with a few examples, after seeing the discussion about negation here

    • I wanted to be able to point to expectation value without the link being broken. So I added a sentence there, but nothing more for the moment.

    • I gave diffiety more of an Idea-section

    • New stub Weyl functional calculus redirecting also Weyl quantization. I would like to see ref.

      • Lars Hörmander, The weyl calculus of pseudo-differential operators, Comm. Pure Appl. Math. 32, 3, 359–443, May 1979, doi,

      but have no access to it (can anybody help?). I also added a sentence at Idea section of functional calculus reflecting that the previous definition there is not fitting functional calculi in the context of quantization, including Weyl’s case. One should do this generality discussion more carefully. the previous definition said that the functional calculus needs to be a homomorphism (from ordinary functions to operator functions). This is true for the functional calculus described in the entry, but not for the wider usage of the phrase like in Weyl functional calculus. Maybe we can resolve this in a better way.

    • I’ve been entering corrections into the article theory of algebraically closed fields in response to a chat room discussion, but see that the \underbrace command doesn’t work as expected (see the Definition section). What’s the right way to write what is obviously wanted here?

    • added the case of dgc superalgebras (here) and expanded the list of examples accordingly

    • created evolutionary derivative (what Olver calls the “Fréchet derivative of tuples of differential functions”) with basic definitions and properties

    • I have recorded citations for integral representations of Bessel functions (here) needed in the computation of the singular support of the Klein-Gordon propagators (here)

    • I gave the definition of symbol order its own entry (an estimate on the decay of the principal symbol of a (psedo-)differential operator that enters the assumptions of the propagation of singularities theorem).

      Maybe there is a better name for this? The literature refers to it mostly only in formal notation as “q∈S ρ,δ m(X)q \in S^m_{\rho, \delta}(X)”.

    • I noticed that exceptional Lie algebra was still a missing entry. Just in order to make links work, I created a stub for it. No time for more at the moment.

    • A while back I had started an overview table propagators - table.

      Now I see that a nice table in this spirit, but larger with much more information, has been produced by some M. B. Kocic. I have added pointer to this pdf in a few places.

    • I gave the entry wave front set more of an Idea-section, and I added pointer to Hörmander’s book.

    • added to advanced and retarded propagator statement and proof of the expression

      Δ R(x,y)=(2π) −(p+1)limε→0 +∫e −ik μx μk μk μ+m 2−ik 0ε/2d 4k \Delta_R(x,y) \;=\; (2\pi)^{-(p+1)} \underset{\epsilon \to 0^+}{\lim} \int \frac{e^{-i k_\mu x^\mu}}{ k_\mu k^\mu + m^2 - i k_0 \epsilon/2 } d^4 k

      (this prop.)

    • I have given generalized function its own little entry (it used to be just a redirect to distribution) with some expository words on how to think of and read distributions as “generalized functions”.

    • Someone started a page called Ahmadnagar. The page is blank otherwise. I tried to find more and googled Ahmadnagar and math and found that in the Ahmadnagar district in India there is a village called Math, with a population of 1851. Strange but it seems true. I have left the nLab page for all to see!

    • I’m pretty sure the definition of a super fiber functor should read ’T = sFinVect’ to agree with the notation earlier in the article rather than the notation in DMOS or Deligne’s paper, where sVect is understood to contain only finite-dimensional super vector spaces. I’ve edited the article to reflect this.

    • Added the Frechet space structure on spaces of smooth sections of the smooth vector bundle: here

    • Created the stub germ of a space, mainly to record the (trivial) insight that the category of germs of spaces is a localization of the category of pointed spaces.

      Note that this is not yet a good stub, as it is not interlinked very well. I’m not quite sure where to put it in the table at germ.

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