$C^0$-characterization of symplectic and contact embeddings and Lagrangian rigidity

TL;DR

This paper introduces a new $C^0$-characterization of symplectic and contact embeddings using shape invariants, providing a novel proof of their rigidity and extending techniques to contact topology.

Contribution

It develops a $C^0$-characterization framework for symplectic and contact embeddings based on shape invariants, linking Lagrangian and coisotropic rigidity.

Findings

Shape invariants characterize symplectic and contact embeddings.

New proof of $C^0$-rigidity for symplectic and contact diffeomorphisms.

Defined a symplectic capacity derived from shape invariants.

Abstract

We present a novel $C^0$-characterization of symplectic embeddings and diffeomorphisms in terms of Lagrangian embeddings. Our approach is based on the shape invariant, which was discovered by J.-C. Sikorav and Y. Eliashberg, intersection theory and the displacement energy of Lagrangian submanifolds, and the fact that non-Lagrangian submanifolds can be displaced immediately. This characterization gives rise to a new proof of $C^0$-rigidity of symplectic embeddings and diffeomorphisms. The various manifestations of Lagrangian rigidity that are used in our arguments come from $J$-holomorphic curve methods. An advantage of our techniques is that they can be adapted to a $C^0$-characterization of contact embeddings and diffeomorphisms in terms of coisotropic (or pre-Lagrangian) embeddings, which in turn leads to a proof of $C^0$-rigidity of contact embeddings and diffeomorphisms. We give a detailed treatment of the shape invariants of symplectic and contact manifolds, and demonstrate that shape is often a natural language in symplectic and contact topology. We consider homeomorphisms that preserve shape, and propose a hierarchy of notions of Lagrangian topological submanifold. Moreover, we discuss shape related necessary and sufficient conditions for symplectic and contact embeddings, and define a symplectic capacity from the shape.