The many forms of rigidity for symplectic embeddings

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Felix Schlenk , Universite de Neuchatel, Switzerland

We look at the following chain of symplectic embedding problems in dimension four.E(1,a)Z4(A)E(1,a)C4(A)E(1,a)P(A,bA)(bN2)E(1,a)T4(A)
Here E(1,a) is a symplectic ellipsoid, Z4(A) is the symplectic cylinder D2(A)×R2,C4(A)=D2(A)×D2(A) is the cube and P(A,bA)=D2(A)×D2(bA) the polydisc, and T4(A)=T2(A)×T2(A), where T2(A) is the 2-torus of area A. In each problem we ask for the smallest A for which E(1,a) symplectically embeds. The answer is very different in each case: total rigidity, total flexibility with a hidden rigidity, and a two-fold subtle transition between them. The talk is based on works by Cristofaro-Gardiner, Frenkel, Latschev, McDuff, Muller, and myself.