In
algebraic group theory, a wonderful compactification of a variety acted on by an algebraic group
is a
-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 of an algebraic group
by the subgroup
fixed by some involution
of
over the
complex numbers, sometimes called the De Concini–Procesi compactification, and generalized this construction to arbitrary characteristic. In particular, by writing a group
itself as a symmetric homogeneous space,
(modulo the diagonal subgroup), this gives a wonderful compactification of the group
itself.
References
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Algebraic groups
Compactification (mathematics)
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