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Nov 23, 2023 at 14:45 vote accept RFZ
Oct 8, 2023 at 6:25 answer added Seva timeline score: 3
Oct 7, 2023 at 23:59 comment added Terry Tao $\chi(x) \in e([-\delta,\delta])$ is equivalent to $|\chi(x)-1| \leq 2 \sin(\pi \delta)$, so one can prove a similar result after adjusting the value of $\delta$ appropriately.
Oct 7, 2023 at 23:49 comment added RFZ @TerryTao, I agree that he uses a definition which is quite different from the one I provided. However, I am wondering if it is possible to prove the same type of result with my definition. I have been trying for a few days, but it has not worked out yet.
Oct 7, 2023 at 23:44 comment added Terry Tao Your definition of a Bohr set is not quite the one that Gowers uses (see youtu.be/… ); he uses the condition $\chi(x) \in e([-\delta,\delta])$ rather than $|\chi(x)-1| \leq \delta$.
Oct 7, 2023 at 20:18 comment added RFZ @Seva, Interesting! I asked this question because I am watching the lecture series 'Introduction to Additive Combinatorics' by Tim Gowers, in which he proved the lemma I was inquiring about. That is why I asked this question. Here is the link: youtube.com/…
Oct 7, 2023 at 19:27 comment added Seva Not that I've checked it carefully, but I think the map is not surjective: in fact, $\mathrm{Bohr}(\Gamma,\delta)$ is Freiman-isomorphic to order $r$ to a subset of $\Lambda\cap[-\delta N/4,\delta N/4]^k$.
Oct 7, 2023 at 18:42 comment added RFZ @NickS, yes exactly.
Oct 7, 2023 at 18:15 comment added Nick S What is $\mathbb Z_{N}$? Is it $\mathbb Z/N \mathbb Z$ ?
Oct 7, 2023 at 18:05 history asked RFZ CC BY-SA 4.0