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Apr 19, 2021 at 19:41 comment added Andrés E. Caicedo @jaRedDRedmp Hello. I believe that measure-theoretic considerations will play a key role in any characterization. They certainly seem to appear prominently in "recent" results. Körner's survey mentions some of them and includes some speculations of his own along these lines.
Apr 19, 2021 at 15:18 comment added tassle Sorry for coming so late, can you explain what do you mean by the "the question of what sets are sets of convergence is not purely topological"?
Apr 13, 2017 at 12:58 history edited CommunityBot
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Aug 8, 2014 at 14:03 comment added Benjamin Dickman (Just a comment, assuming I haven't misunderstood.) To show that $\sum_{n} \frac{z^n}{n}$ converges for $C \ni z \neq 1$ (as you mention is shown in Rudin using trigonometric estimates) can be done very quickly with the Dirichlet Convergent Test, or -- even better! -- with the quick geometric proof provided here: mathoverflow.net/q/109582/22971
Jan 28, 2013 at 10:12 comment added Martin The question came up on SE again: math.stackexchange.com/q/288765 user mrf refers to Lukašenko S. Ju., Sets of divergence and nonsummability for trigonometric series, Vestnik Moskov. Univ. Ser. I Mat. Mekh. 1978, no. 2, 65–70 for the result that there is a $G_\delta$-set which is not a set of convergence.
Jan 12, 2012 at 21:21 history edited Andrés E. Caicedo CC BY-SA 3.0
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Dec 15, 2010 at 16:02 comment added Andrés E. Caicedo @Kimball : Yes.
Dec 15, 2010 at 16:00 comment added Kimball I assume $F_\sigma$ means countable union of closed subsets, yes?
Dec 15, 2010 at 10:48 vote accept Piotr
Dec 15, 2010 at 2:00 comment added J. M. isn't a mathematician I'll just point out that the two papers Andres is referring to are both available at Project Euclid: dx.doi.org/10.1215/S0012-7094-49-01647-6 and dx.doi.org/10.1215/S0012-7094-53-02005-5
Dec 14, 2010 at 19:17 comment added Theo Buehler @Andres: I second Andrey's comment full-heartedly. This is indeed very interesting, thanks a lot!
Dec 14, 2010 at 18:57 comment added Andrés E. Caicedo @Theo : Thanks. I fixed the typo and added some remarks. @Andrey: Many thanks!
Dec 14, 2010 at 18:56 history edited Andrés E. Caicedo CC BY-SA 2.5
Added some remarks in light of comments
Dec 14, 2010 at 18:35 comment added Andrey Rekalo @Andres Caicedo: That's a very thorough answer!
Dec 14, 2010 at 18:17 comment added Theo Buehler I think it's worth pointing out that the main effort of the second paper is to provide examples of schlicht (= injective and holomorphic in the open unit disk) Taylor series whose points of convergence not $F_{\sigma}$ on the unit circle. They also mention that the work of Féjer is sufficient to produce examples of non-$F_{\sigma}$-sets of divergence (I believe that this is tightly connected with Gerald Edgar's comment on Fourier series).
Dec 14, 2010 at 17:25 history answered Andrés E. Caicedo CC BY-SA 2.5