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    • brief category:people-entry for hyperlinking references

      v1, current

    • I’ll be working a bit on supersymmetry.

      Zoran, you had once left two query boxes there with complaints. The second one is after this bit of the original entry (this will change any minute now)

      The theory of supergravity is, as a classical field theory, an action functional on functions on a supermanifold XX which is invariant under the super-diffeomorphism group of XX.

      where you say

      Zoran: action functional is on paths, even paths in infinitedimensional space, but not on point-functions.

      I think you got something mixed up here. If XX is spacetime, a field on XX is the “path” that you want to see. The statement as given is correct, but I’ll try to expand on it.

      The second complaint is after where the original entry said

      many models that suggest that the familiar symmetry of various action functionals should be enhanced to a supersymmetry in order to more properly describe fundamental physics.

      You wrote:

      This is doubtful and speculative. There are many models which have supersymmetry which is useful in their theoretical analysis, but the same models can be treated in formalisms not knowing about supersymmetry. Wheather the fundamental physics needs a model which has nontrivial supersymmetry is a speculative statement, and I disagree with equating theoretical physics with one direction in “fundamental physics”. I do not understand how can a model suggest supersymmetry; it is rather experimental evidence or problems with nonsupersymmetric models. Also one should distinguish the supersymmetry at the level of Lagrangean and the supersymmetry which holds only for each solution of the equation of motion.

      I’ll rephrase the original statement to something less optimistic, but i do think that supersymmetry is suggsted more by looking at the formal nature of models than by lookin at the nature of nature. If you have a gauge theory for some Lie algebra (gravity, Poincaré Lie algebra) and the super extension of the Lie algebra has an interesting classification theory (the super Poincar´ algebra) then it is more th formalist in us who tends to feel compelled to investigate this than the phenomenologist. Supersymmetry is studied so much because it looks compelling on paper. Not because we have compelling phenomenological evidence. On the contrary.

      So, if you don’t mind, I will remove both your query boxes and slightly polish the entry. Let’s have any further discussion here.

    • in order to satisfy links, but maybe really in procrastination of other duties, I wrote something at quantum gravity

    • Started an article on monoidal monad. An earlier redirect had sent it over to Hopf monad which is something that Zoran was working on, but I think it deserves an article to itself, with discussion of the relation to commutative monads, etc. (which I have started).

    • added illustrating diagram to transfinite composition

      I also renamed the resulting composite morphism into  X \to Y . Hope I did this consistently.

    • brief category:people-entry for hyperlinking references

      v1, current

    • created quick stub for framed bicategory

      but my machine's battery will die any second now...

    • brief category:people-entry for hyperlinking references

      v1, current

    • Creating the page. Described briefly both the usual Lack model structure and the model structure using semi-strict equivalences coming from my thesis. A lot more could be added.

      v1, current

    • I made the former entry "fibered category" instead a redirect to Grothendieck fibration. It didn't contain any addition information and was just mixing up links. I also made category fibered in groupoids redirect to Grothendieck fibration

      I also edited the "Idea"-section at Grothendieck fibration slightly.

      That big query box there ought to be eventually removed, and the important information established in the discussion filled into a proper subsection in its own right.

    • Created the page (Idea, Syntax, Example, Typing and References)

      v1, current

    • Added the Yoneda-embedding way to talk about group objects and hence supergroups.

    • Somebody from the technical team kindly alerted me that we have a full .mov copy of the video recording of Kapranov 2013 sitting on the nLab server – which is strange (but also lucky), does anyone know/remember how this came to be?

      In trying to understand what’s going on, I noticed that the relevant YouTube link at Kapranov 2013 had died (“private”) as had my original video link from comment #5 in the original thread. Also the links to the hosting conference had meanwhile rotted away.

      I have now

      recovered the conference links via the WaybackMachine,

      added the link to our local copy of the video recording

      and am also uploading the video to YouTube.

      Am propagating these edits also to other entries where Kapranov’s talk is referenced, such as at Mikhail Kapranov and at spectral super-scheme.

      diff, v61, current

    • locally cartesian (,1)(\infty, 1)-categories


      v1, current

    • Created, with so far just an overview of all the possibilities.

      v1, current

    • Added material on diagonal maps and the product functor, mentioning for instance the fact that the product functor is right adjoint to a diagonal functor.

      diff, v22, current

    • A stub, for the moment just to have a place for recording a couple of references (which were previously at fusion category.

      v1, current

    • Added the contents of the canonical isomorphism induced by some non-canonical isomorphism as coming from Lack’s proof.

      diff, v32, current

    • in analogy to what I just did at classical mechanics, I have now added some basic but central content to quantum mechanics:

      • Quantum mechanical systems

      • States and observables

      • Spaces of states

      • Flows and time evolution

      Still incomplete and rough. But I have to quit now.

    • brief category:people-entry for hyperlinking references

      v1, current

    • Asked to clarify, made a definition.


      v1, current

    • I noticed that the entry classifying space is in bad shape. I have added a table of contents and tried to structure it slightly, but much more needs to be done here.

      I have added a paragraph on standard classifying spaces for topological principal bundles via the geometric realization of the simplicial space associated to the given topological group.

      In the section “For crossed complexes” there is material that had been provided by Ronnie Brown which needs to be harmonized with the existing Idea-section. It proposes something like a general axiomatics on the notion of “classifying space” more than giving details on the geometric realization of crossed complexes

    • The Idea-section at quasi-Hopf algebra had been confused and wrong. I have removed it and written a new one.

    • Following discussion in some other threads, I thought one should make it explicit and so I created an entry

      Currently this contains some (hopefully) evident remarks of what “dependent linear type theory” reasonably should be at least, namely a hyperdoctrine with values in linear type theories.

      The entry keeps saying “should”. I’d ask readers to please either point to previous proposals for what “linear dependent type theory” is/should be, or criticise or else further expand/refine what hopefully are the obvious definitions.

      This is hopefully uncontroversial and should be regarded an obvious triviality. But it seems it might be one of those hidden trivialities which deserve to be highlighted a bit more. I am getting the impression that there is a big story hiding here.

      Thanks for whatever input you might have.

    • brief category:people entry for hyperlinking reretences

      v1, current

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

      v1, current

    • added an Examples-section (here) “In 2d gravity on String worldsheets”

      diff, v3, current