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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeMay 8th 2012
    • (edited May 8th 2012)

    I have worked a bit on contractible type. Apart from beautifying it a bit (or so I hope I did) I have added in the section Categorical semantics a fair bit of pedestrian detail on how to see that a term of isContr(A)isContr(A) is indeed a contraction right homotopy, and vice versa.

    • CommentRowNumber2.
    • CommentAuthorMike Shulman
    • CommentTimeMay 9th 2012

    Excellent, thank you. I corrected some \dashvs to \vdashs.

  1. adding examples of contractible types


    diff, v16, current

  2. added third definition of contractible type, and replaced depreciated Markdown notation for definitions/theorems/propositions/proofs with LaTeX notation.


    diff, v17, current

  3. adding natural deduction syntax rules for isContr


    diff, v18, current

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeDec 27th 2022
    • (edited Dec 27th 2022)

    added pointer to what I guess is the original document with the notion of contractible types:

    diff, v22, current

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeDec 27th 2022
  4. adding link to universal quantifier


    diff, v24, current

    • CommentRowNumber10.
    • CommentAuthorUrs
    • CommentTimeJan 21st 2023
    • (edited Jan 21st 2023)

    A couple of entries are requesting a link for “singleton contractibility”

    (e.g. function extensionality, identity type and higher observational type theory).

    It seems weird to leave such a basic notion undefined in these entries. Since I am assuming that it is meant to point to the notion of singleton induction discussed in this entry here, I have now made “singleton contractibility” redirect to here.

    (If it should go elsewhere, remove the redirect and create the necessary entry!)

    diff, v25, current