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    • CommentRowNumber1.
    • CommentAuthorJohn Baez
    • CommentTimeDec 3rd 2009
    I added more info on pseudo double categories and double bicategories to double category. I also simplified the picture of a square, which had been bristling with scary unnecessary detail. There's a slight blemish in the left vertical arrow, which I can't see how to fix.
    • CommentRowNumber2.
    • CommentAuthorTobyBartels
    • CommentTimeDec 4th 2009

    Urs fixed it.

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeJul 12th 2018

    added pointer to Ehresmann 63

    diff, v53, current

    • CommentRowNumber4.
    • CommentAuthorTim_Porter
    • CommentTimeDec 29th 2018
    • (edited Dec 29th 2018)

    There was a strange line break added in a recent anonymous edit that mucked up the reference to Brown and Higgins’s paper. Strangely although it mucked up the viewed page the error introduced did not show on the ’latest changes’ view!

    diff, v57, current

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeDec 29th 2018
    • (edited Dec 29th 2018)

    Yes, this is a phenomenon that affects several pages. It must have been introduced not by an edit to these pages, but by one of the recent changes to the rendering software. I guess we should just fix all occurences by hand, as we encounter them.

  1. attempt to introduce string diagrams

    Antonin Delpeuch

    diff, v58, current

  2. improve string diagram so that notations with first diagram are consistent

    Antonin Delpeuch

    diff, v58, current

    • CommentRowNumber8.
    • CommentAuthorDmitri Pavlov
    • CommentTimeJul 2nd 2020

    Added the gregarious model structure on double categories.

    diff, v61, current

    • CommentRowNumber9.
    • CommentAuthorMike Shulman
    • CommentTimeJul 30th 2020

    Where does the name “gregarious” come from?

    • CommentRowNumber10.
    • CommentAuthorMike Shulman
    • CommentTimeJul 30th 2020

    Added mention and citations of various other model structures on DblCat.

    diff, v62, current

    • CommentRowNumber11.
    • CommentAuthorMike Shulman
    • CommentTimeJul 30th 2020

    The only reference I could find for the gregarious model structure was some slides from a talk. Is there more?

  3. Removed the phrase “conjectured to be”.

    Alexander Campbell

    diff, v63, current

    • CommentRowNumber13.
    • CommentAuthorGuest
    • CommentTimeJul 30th 2020
    Re #9: The word "gregarious" is used a few places in the double category literature (e.g. in relation to companions and conjoints. In the present context it refers to the "gregarious equivalences" which describe the weak equivalences and fibrations of this model structure.

    Re #11: There will be a paper eventually, but it's at the bottom of my to-do list.

    Alexander Campbell
    • CommentRowNumber14.
    • CommentAuthorMike Shulman
    • CommentTimeJul 30th 2020


    I’m impressed that you anticipate ever reaching the bottom of your to-do list. I gave up any hope of that years ago. (-:O

  4. Alas, by the time I get around to writing it, it will no longer be at the bottom of my to-do list ;-)
    • CommentRowNumber16.
    • CommentAuthorUrs
    • CommentTimeAug 28th 2021

    added pointer to:

    diff, v70, current

    • CommentRowNumber17.
    • CommentAuthorMike Shulman
    • CommentTimeOct 26th 2021

    Added reference

    • {#MSVHInvar} Lyne Moser, Maru Sarazola, Paula Verdugo, A model structure for weakly horizontally invariant double categories, arxiv, 2020

    diff, v72, current

    • CommentRowNumber18.
    • CommentAuthorDavid_Corfield
    • CommentTimeMay 31st 2022

    Added a reference

    diff, v73, current

    • CommentRowNumber19.
    • CommentAuthormattecapu
    • CommentTimeOct 16th 2022

    added Grandis’ textbook in references

    diff, v77, current

    • CommentRowNumber20.
    • CommentAuthormattecapu
    • CommentTimeOct 16th 2022

    added awesome double categories to the references

    diff, v78, current

    • CommentRowNumber21.
    • CommentAuthormattecapu
    • CommentTimeOct 26th 2022

    added related page: multiple category

    diff, v80, current

    • CommentRowNumber22.
    • CommentAuthorBryceClarke
    • CommentTimeJan 16th 2023

    Added link to the Virtual Double Categories Workshop, held in 2022, which contains slides and recordings from 19 talks on double categories.

    diff, v81, current

    • CommentRowNumber23.
    • CommentAuthorUrs
    • CommentTimeJun 2nd 2023

    I have extracted out of the “collected works” a small pdf file with just this article:

    • Charles Ehresmann, Catégories double et catégories structurées, C.R. Acad. Paris 256 (1963) 1198-1201

    diff, v85, current

    • CommentRowNumber24.
    • CommentAuthorvarkor
    • CommentTimeJun 9th 2023

    Provide a link to a characterisation of one-object double categories.

    diff, v86, current

  5. Added references to some important works by Grandis and Pare

    Patrick Nicodemus

    diff, v87, current

    • CommentRowNumber26.
    • CommentAuthorvarkor
    • CommentTimeJan 16th 2024

    Add a reference for the multicategory structure.

    diff, v89, current