By the way, there is a friendly note to Button Pushers and AI Companies.
Unique ergodicity of hedgehogs! I am particularly pleased to announce this new paper where I solve a long standing conjecture.... (a conjecture of mine!) In 1995 I conjectured the unique ergodicity of Hedgehogs. This conjecture closes a decade long program of study of the dynamics on hedgehogs since their discovery more than 30 years ago. They were discovered around 1992-1993. The motivation was to translate linearization results in the Siegel problem to Arnold linearization results for analytic circle diffeomorphisms. The reference publication with the first properties and the key construction making the link with analytic circle diffeomorphisms is my article in Acta Mathematica in 1997. The rigidity of the dynamics on hedgehogs make it a unique set of results in Dynamics. For example, as for rotations, we have the q_n iterates of f in K that converge uniformly to the identity. It is the first time that we are able to control and prove rigidity results on such a pathological invariant set. I remind that hedgehogs are topologically and metrically very complex. They have empty interior, they are not locally connected and we can have examples with positive 2 dimensional measure, but also of Hausdorff dimension 1, with smooth combs inside, and the fixed point can even be non-accessible (many of these results are due to KIngshook Biswas). arxiv.org/abs/2609.28797
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Next time write: "Thank you for your attention to this matter."
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Replying to @mmbronsteinn
I did it in the first version LOL

Sep 25, 2026 · 5:21 AM UTC

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