= Displacement energy
{disambiguate=symplectic geometry}
{title2=$e(A)=\inf_{\phi(A)\cap A=\varnothing}d_H(\mathrm{id},\phi)$}
= Hamiltonian displacement energy
{c}
{synonym}
The displacement energy of a subset of a <symplectic manifold> is the infimum of the energy norms of compactly supported <Hamiltonian diffeomorphisms> moving it off itself. The infimum is $+\infty$ if no such map exists. One must use the same chosen norm convention in both this definition and any energy lower bound. A compact set can have zero displacement energy even when every nonidentity map has positive norm.
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