= Capacity of a bounded set thickened by a symplectic subspace
{title2=$0<c(U+W)<\infty$}
If $U$ is nonempty, bounded and open in standard symplectic Euclidean space, and $W$ is a codimension-two <symplectic subspace>, a linear symplectic change of coordinates makes $W=\{q_1=p_1=0\}$. Boundedness of the remaining coordinate projection places $U+W$ inside a finite-radius <symplectic cylinder>. Openness puts a small ball inside it. Monotonicity and normalization of a <symplectic capacity> give the displayed strict bounds.
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