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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeDec 3rd 2020

    I am giving this its own little entry, for ease of collecting some facts and resources…

    …such as the MO discussions (MO:a/44885/381, MO:a/218053/381) on how K324S 3K3 \setminus 24 S^3 is the cobordism that witnesses 24[S 3]=0Ω 3 fr24 [S^3] = 0 \in \Omega^{fr}_3. There must be a more citeable reference for this, though. If anyone has the pointer, let’s add it.

    v1, current

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeDec 3rd 2020
    • (edited Dec 3rd 2020)

    added pointer to:

    • Guozhen Wang, Zhouli Xu, Section 2.6 of: A survey of computations of homotopy groups of Spheres and Cobordisms, 2010 (pdf)

    v1, current

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeDec 3rd 2020

    added a graphics

    diff, v2, current

    • CommentRowNumber4.
    • CommentAuthorDavidRoberts
    • CommentTimeDec 4th 2020

    @Urs, you can strip off the /381 from the url, it’s only there to track clicks via links that you have shared. cf https://mathoverflow.net/users/381/. The answer itself is identified by only the first number.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeDec 18th 2020

    added mentioning (here) of π 3 s\pi_3^s seen as the images under half the Todd class of (SU,Fr)-structured 4-manifolds with boundary (as per the last pages of Conner-Floyd 66)

    diff, v8, current

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeDec 21st 2020

    added this pointer:

    diff, v11, current