Wonderful compactification explained

In algebraic group theory, a wonderful compactification of a variety acted on by an algebraic group

G

is a

G

-equivariant compactification such that the closure of each orbit is smooth. constructed a wonderful compactification of any symmetric variety given by a quotient

G/G\sigma

of an algebraic group

G

by the subgroup

G\sigma

fixed by some involution

\sigma

of

G

over the complex numbers, sometimes called the De Concini–Procesi compactification, and generalized this construction to arbitrary characteristic. In particular, by writing a group

G

itself as a symmetric homogeneous space,

G=(G x G)/G

(modulo the diagonal subgroup), this gives a wonderful compactification of the group

G

itself.

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