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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeAug 31st 2011
    • (edited Aug 31st 2011)

    I have cross-linked the quadruple of entries

    Euclidean geometry, Klein geometry

    Riemannian geometry, Cartan geometry

    and briefly edited the entries otherwise. For instance added an Idea-sentence to Euclidean geometry, and expanded Klein geometry (for instance the Examples).

    • CommentRowNumber2.
    • CommentAuthorzskoda
    • CommentTimeAug 31st 2011

    There is no entry Riemann geometry, possibly Riemannian geometry.

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeAug 31st 2011

    thanks, fixed.

    • CommentRowNumber4.
    • CommentAuthorTodd_Trimble
    • CommentTimeJan 4th 2015

    At Euclidean geometry, a new batch of material on axiomatizations, including a discussion on Tarski’s geometry.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeJan 4th 2015

    Thanks. I have added mentioning of the word synthetic geometry here

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeJan 4th 2015
    • (edited Jan 4th 2015)

    Stupid question regarding the statement that “Hilbert’s theory is categorical”: is there are any chance that one could say “is categoric” ?? To avoid the clash of terminology (at least of associations).

    • CommentRowNumber7.
    • CommentAuthorDavid_Corfield
    • CommentTimeJan 4th 2015

    Have people given more obviously type theoretic renditions of geometries such as the Euclidean one? I could imagine advantages to having more than Tarski’s single sort.

    In the projective case, I guess we’d see the duality symmetry of exchanging the line and point types.

    • CommentRowNumber8.
    • CommentAuthorTodd_Trimble
    • CommentTimeJan 4th 2015
    • (edited Jan 4th 2015)

    Urs #6: I’d not heard that suggestion before. Toby is one of those who advise category theorists to say “categorial” for their own meaning instead of “categorical”, to avoid this clash. I don’t like this much personally; something about it seems too subservient to model theory (I would guess mathematicians say “categorical” in the, um, categorical sense much more often than in the model-theoretic sense).

    Honestly, I don’t mind inventing a new word for the purposes of the nLab. If someone edits in “categoric” with a link, I won’t say a thing. Either way I’ll be at peace. :-)