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  1. It should be clarified that type checking is decidable, not e.g Type inhabitation or some other property.


    diff, v10, current

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeMay 13th 2021
    • (edited May 13th 2021)

    Made a pdf copy for:

    diff, v11, current

    • CommentRowNumber3.
    • CommentAuthorMike Shulman
    • CommentTimeSep 1st 2022

    Added explanation of “extensional” vs “intensional”.

    diff, v13, current

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeSep 1st 2022

    To further clarify this it would help to hyperlink “extensionality principles”. We have extension (semantics), but currently this does not really explain much.

    Looking around, I see that the first paragraph of Wikipedia’s entry Extensionality is helpful. It would be nice if we had something along these lines on the nLab.

    diff, v14, current

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeJan 18th 2023
    • (edited Jan 18th 2023)

    I have added reference to

    • Thomas Streicher, Investigations into Intensional Type Theory, Habilitation Thesis, Darmstadt (1993) [pdf]

    and added pointers in the text to where concretely (on which pages) Streicher and then Hofman touch on the issue at hand.

    I have also adjusted the wording throughout, in particular in the “Remark on terminology” (now here).

    (It is a pity that such an important topic ended up with such a murky and confusing terminology.)

    diff, v16, current