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Apr 10, 2018 at 5:25 history edited Hebe CC BY-SA 3.0
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Apr 10, 2018 at 4:17 comment added Mikhail Borovoi Yes, this is true, see Helgason's book, X.6.4, case (vii).
Apr 10, 2018 at 4:01 comment added Hebe @MikhailBorovoi Thank you for your answer, professor Borovoi. Yes, that is what I mean. Now let $G=\mathrm{Spin}^*(2n)$. It is known that $\mathrm{Spin}(6)\cong\mathrm{SU}(4)$. Thus, is it true that $\mathrm{Spin}^*(6)\cong\mathrm{SU}(3,1)$?
Apr 9, 2018 at 17:58 comment added Mikhail Borovoi If this is what you mean, then the answer is $G={\rm Spin}^*(2n)$, the universal cover of the group $G={\rm SO}^*(2n)$. The latter is the group of quaternionic $n\times n$ -matrices with determinant 1, preserving a nondegenerate skew-hermitian form, for example, the form with matrix ${\rm diag }(i,i,\dots,i)$.
Apr 9, 2018 at 17:47 comment added Mikhail Borovoi What do you mean by "Then there exists a noncompact closed subgroup $G$ of $G_{\Bbb C}={\rm Spin}(2n,{\Bbb C})$" ? Do you mean a closed subgroup with Lie algebra $\mathfrak g_0$?
Apr 9, 2018 at 14:50 history asked Hebe CC BY-SA 3.0