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In algebraic group theory, a wonderful compactification of a variety acted on by an algebraic group G is a G-equivariant
compactification Compactification may refer to: * Compactification (mathematics), making a topological space compact * Compactification (physics), the "curling up" of extra dimensions in string theory See also * Compaction (disambiguation) Compaction may refer t ...
such that the closure of each orbit is smooth. constructed a wonderful compactification of any
symmetric variety Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definiti ...
given by a quotient G/G^ of an algebraic group G by the subgroup G^ 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 \times G)/G (modulo the diagonal subgroup), this gives a wonderful compactification of the group G itself.


References

* * * * * Algebraic groups Compactification (mathematics) {{abstract-algebra-stub