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D.6.14.3 QuotientEquations
Procedure from library qhmoduli.lib (see qhmoduli_lib).
- Usage:
- QuotientEquations(G,action,emb [, opt]); ideal G,action,emb;int opt
- Purpose:
- compute the quotient of the variety given by the parameterization
'emb' by the linear action 'action' of the algebraic group G.
- Assume:
- 'action' is linear, G must be finite if the Reynolds operator is
needed (i.e., NullCone(G,action) returns some non-invariant polys)
- Return:
- polynomial ring over a simple extension of the ground field of the
basering, containing the ideals 'id' and 'embedid'.
- 'id' contains the equations of the quotient, if opt = 1;
if opt = 0, 2, 'id' contains generators of the coordinate ring R
of the quotient (Spec(R) is the quotient)
- 'embedid' = 0, if opt = 1;
if opt = 0, 2, it is the ideal defining the equivariant embedding
- Options:
- 1 compute equations of the quotient,
2 use a primary decomposition when computing the Reynolds operator,
to combine options, add their value, default: opt =3.
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