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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeAug 14th 2015
    • (edited Aug 14th 2015)

    I have added pointer to

    to the entries 7-sphere, ADE classification, Freund-Rubin compactification.

    This article proves the neat result that the finite subgroups Γ\Gamma of SO(8)SO(8) such that S 7/ΓS^7/\Gamma is smooth and spin and has at least four Killing spinors has an ADE classification. The Γ\Gammas are the the “binary” versions of the symmetries of the Platonic solids.

    • CommentRowNumber2.
    • CommentAuthorTodd_Trimble
    • CommentTimeAug 16th 2015

    I added some more material to 7-sphere, mostly on exotic smooth structures.

    • CommentRowNumber3.
    • CommentAuthorDavidRoberts
    • CommentTimeAug 16th 2015

    I mentioned that these exotic spheres are called Brieskorn manifolds or spheres and corrected a typo (z 42z^{42} – !)

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeSep 8th 2016

    Added statement of the canonical (nearly parallel) G 2G_2-structure on the 7-sphere – here.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeMar 26th 2019
    • (edited Mar 26th 2019)

    Thanks! Have added these here

    [this was in reply to the message here, in another thread]

    diff, v20, current

    • CommentRowNumber6.
    • CommentAuthorDavid_Corfield
    • CommentTimeApr 19th 2019

    Added comment and reference to John Baez’s account of the 4 coset realizations.

    diff, v22, current

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