Definition:Symplectic Basis
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Definition
Let $\mathbb K$ be a field.
Let $\struct {V, f}$ be a bilinear space over $\mathbb K$ of finite dimension $2 n > 0$.
Let $\BB = \tuple {b_1, c_1, \ldots, b_n, c_n}$ be an ordered basis of $V$.
Then $\BB$ is symplectic if and only if:
- $\map f {b_i, b_j} = \map f {c_i, c_j} = 0$ for all $i, j$
- $\map f {b_i, c_j} = \delta_{i j}$ for all $i, j$
where $\delta$ denotes Kronecker delta.
That is, if and only if the matrix of $f$ relative to $\BB$ has the form:
- $\begin{pmatrix} 0 & 1 \\ -1 & 0 \\ & & 0 & 1 \\ & & -1 & 0 \\ & & & & \ddots \\ & & & & & 0 & 1 \\ & & & & & -1 & 0 \end{pmatrix}$
Also see
Sources
- Weisstein, Eric W. "Symmetric Bilinear Form." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/SymmetricBilinearForm.html