Lie Groups and Lie Algebras: Lesson 11 - The Classical Groups Part IX

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Lie Groups and Lie Algebras: Lesson 11 - The Classical Groups Part IX

In this lecture we count the degrees of freedom for the classical groups.

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Between 31:27 and 31.50, you seem to confuse the *symmetry between the elements* (symmetric/anti-symmetric ) with the *functional form of the metric* (bilinear or sesquilinear). An an example: bilinear means that (αeₖ, eₗ) = gₖₗ α and symmetric means gₖₗ = gₗₖ. For info only for all: I rewrote the table as follows (where * means the transposed value ).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - -
bilinear sesquilinear
(α eₖ, eₗ) = gₖₗ α (α eₖ, eₗ) = (gₖₗ)*α*
- - - - - - - -- - - - - - - - - - - - - - - - - - - - -
- - -
symmetric: gₖₗ = gₗₖ and F=R O(N₊, N₋; F) ---
hermetian: gₖₗ = (gₗₖ)* and F=C, Q O(N₊, N₋; F) U(N₊, N₋ ; F)
anti-symmetric: gₖₗ = - gₗₖ and F=R, C, Q Sp(2N; F) ---
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - -
I also defined three types of symmetry: symmetric, hermetian and anti-symmetric (this also explains the difference in notation: Gilmore uses the word symmetric for all F=R, C, Q while you uses the word symmetric when F=R and the word hermetian when F=C, Q).

jacquessmeets
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Your matrix example at around 15:40 is not right. The displayed matrix shoul have 0 diagonal . In fact, symplectic matrices have pairs of +1, -1 around a 0 diagonal

antoniomranz