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Aug 13, 2018 at 16:47 comment added K.K. @JürgenBöhm Yes, that is the issue here -- even in a topologically trivial family of complex manifolds, you'll need further assumptions to ensure that all of the fibers are isomorphic as complex manifolds.
Aug 13, 2018 at 16:34 comment added Jürgen Böhm @Tony You are right, I was somehow thinking the usual result of Ehresmann would "strengthen itself" when one goes to the category of complex manifolds. But there is probably something more subtle involved here, which I am currently not aware of - does it have to do with "variation of complex structure in the family $f:X \to S$"?
Aug 13, 2018 at 16:12 comment added K.K. Nitpick: Ehresmann's theorem only guarantees that there is a diffeomorphism between $X_s$ and $X_{s'}$, not a biholomorphism.
Aug 12, 2018 at 22:53 comment added Donu Arapura You're welcome. By the way, a reference for the degeneration is theoreme 5.5 of Deligne, Theoreme de Lefschetz et criteres de degenerescence de suites spectrales
Aug 12, 2018 at 22:45 comment added Jürgen Böhm @Donu Arapura Thank you very much for taking the time to look at my proof (attempt)! I really had hoped that Q3 would be right, because I want to base an algorithm for explicitly calculating the Gauss-Manin connection in Macaulay2 on it.
Aug 12, 2018 at 22:34 comment added Donu Arapura Oh, I missed the fact you're assuming $S$ is affine. Then Q3 is OK, but the splitting would be highly unnatural.
Aug 12, 2018 at 21:24 comment added Donu Arapura I don't have time to check carefully; your basic strategy seems fine initially. However the answer to Q3 is no, it won't split except in trivial cases.
Aug 12, 2018 at 20:47 history asked Jürgen Böhm CC BY-SA 4.0