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nLab > Latest Changes: Serre fibration

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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeApr 1st 2016

    at Serre fibration I have spelled out the proof that that with F x↪X→fibYF_x \hookrightarrow X \overset{fib}{\to} Y then π •(F)→π •(X)→π •(Y)\pi_\bullet(F) \to \pi_\bullet(X)\to \pi_{\bullet(Y)} is exact in the middle. here.

    (This is intentionally the low-technology proof using nothing but the definition. )

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeJul 18th 2017

    Added to Serre fibration a section Properties – Relation to Hurewicz fibrations with pointer to

    a) counter-example of a Serre fibration that is not a Hurewicz fibration

    b) statement that all Serre fibrations between CW-complexes are Hurewicz fibrations.

    Also added to the Examples-section pointer to the homotopy lifting property for covering spaces.

    • CommentRowNumber3.
    • CommentAuthorDavidRoberts
    • CommentTimeJul 19th 2017

    (The projection map of) a fibre bundle over any paracompact space, or more generally, a bundle that admits a trivialisation over a numerable cover, is a Hurewicz fibration, I believe.. In general, all fibre bundles are Serre fibrations.

    (I was torn between adding this comment here or at the covering space thread)

    • CommentRowNumber4.
    • CommentAuthorDexter Chua
    • CommentTimeJul 29th 2017

    Fixed some syntax errors

    • CommentRowNumber5.
    • CommentAuthorTim_Porter
    • CommentTimeDec 29th 2018

    The ’in particulars’ were ’breeding thick and fast’ in certain parts of this page! I removed one of them to keep the population down.

    diff, v17, current

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeMar 22nd 2021
    • (edited Mar 22nd 2021)

    added the statement (here) that a map is a Serre fibration if its pullback along a numberable open cover is so

    diff, v20, current

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeMar 22nd 2021
    • (edited Mar 22nd 2021)

    I replaced the previous half-sentence claiming that “every” fiber bundle is a Serre fibration by some more detailed statement mentioning numerable fiber bundles and paracompact base spaces, and providing the proof (here)

    diff, v20, current

  8. Removed the references to May’s Concise course, since it does not treat Serre fibrations (cf. “”)

    Anonymous

    diff, v21, current

  9. Removed the references to May’s Concise course, since it does not treat Serre fibrations (cf. §7.1: “Serre fibrations are more appropriate for many purposes, but we shall make no use of them.”); recognition over numerable convers is a theorem about Hurewicz fibrations, so it would fit better on that page. (For a map f:X→Yf\colon X\to Y to be a Serre fibration it suffices for f| f −1(U)f −1(U)→Uf|_{f^{-1}(U)}f^{-1}(U)\to U to be a Serre fibration for all UU in any open cover of YY; to sketch the construction of the lift: subdivide the I n+1I^{n+1} into a grid of closed subcubes whose image lies in some UU, and construct the lift inductively, starting in the corner with the origin.)

    Anonymous

    diff, v21, current

    • CommentRowNumber10.
    • CommentAuthorUrs
    • CommentTimeMar 24th 2021

    Thanks for the alert. I’ll fix it when I am back online (on my phone now).

  11. Put in a reference for the statement I just gave to tom Dieck’s 2008 book. The stuff about numerable covers is now at Hurewicz fibration.

    (Hope I got the formatting right – I’m a long time reader, first time editor…)

    Anonymous

    diff, v22, current

    • CommentRowNumber12.
    • CommentAuthorUrs
    • CommentTimeMar 24th 2021

    Thanks a million! For all this (catching it, fixing it across pages, and last not least, for setting me straight – much appreciated).

    • CommentRowNumber13.
    • CommentAuthorUrs
    • CommentTimeApr 3rd 2021

    I have expanded out the statement at local recognition a little, just for beautification.

    diff, v24, current

    • CommentRowNumber14.
    • CommentAuthorUrs
    • CommentTimeApr 16th 2021

    added pointer to:

    diff, v26, current

    • CommentRowNumber15.
    • CommentAuthorUrs
    • CommentTimeApr 16th 2021

    added the example of empty bundles (here)

    diff, v26, current

1 to 15 of 15

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