An elementary proof of the symplectic spectral theorem

Camilo Sanabria Malagón

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arXiv · 1710.00697

An elementary proof of the symplectic spectral theorem

Camilo Sanabria Malagón

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Abstract

The classical spectral theorem completely describes self-adjoint operators on finite dimensional inner product vector spaces as linear combinations of orthogonal projections onto pairwise orthogonal subspaces. We prove a similar theorem for self-adjoint operators on finite dimensional symplectic vector spaces over perfect fields. We show that these operators decompose according to a polarization, i.e. as the product of an operator on a lagrangian subspace and its dual on a complementary lagrangian. Moreover, if all the eigenvalues of the operator are in the base field, then there exist a Darboux basis such that the matrix representation of the operator is two-by-two blocks block-diagonal, where the first block is in Jordan normal form and the second block is the transpose of the first one.

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Camilo Sanabria Malagón. 2017-09-29. An elementary proof of the symplectic spectral theorem. https://arxiv.org/abs/1710.00697

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