On Gromov Width under $C^0$ Deformations

Abstract

We construct a uniformly bounded symplectic structure on $S^2 \times \mathbb{R}^4$ admitting embeddings by arbitrarily large balls. This provides a counterexample to a recent conjecture of Savelyev. We then prove the conjecture holds for a wide class of examples, generalizing a result by Savelyev. Along the way, we clarify some aspects of pseudoholomorphic curve theory in non-compact manifolds.