Mike Usher

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Name Mike Usher
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Mar
25
awarded  Nice Answer
Jan
12
comment real symmetric matrix has real eigenvalues - elementary proof
I'm confused by your (2)...doesn't putting $S=\left(\begin{array}{cc} 0 & 1 \\ 1 & 0\end{array}\right)$ and $z=\left(\begin{array}{c} 1 \\ 0\end{array}\right)$ give a counterexample? The statement that $\langle Sz,z\rangle=0$ isn't enough to imply that $z$ is orthogonal to the range.
Jan
11
accepted On the de Rham cohomology of 1-forms in cotangent bundle.
Jan
11
comment On the de Rham cohomology of 1-forms in cotangent bundle.
In your example on $S^1$, note that the vertical translation on the cylinder is a symplectic isotopy but is not Hamiltonian (i.e. is not given by the flow of the Hamiltonian vector field of a time-dependent function--its flux is nonzero). So if one is restricting to Hamiltonian flows (as the OP seems to be doing) this example doesn't apply.
Jan
11
answered On the de Rham cohomology of 1-forms in cotangent bundle.
Dec
26
awarded  Nice Answer