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7.5.19.0. admissibleSub
Procedure from library ncpreim.lib (see ncpreim_lib).
- Usage:
- admissibleSub(v); v intvec
- Assume:
- The entries of v are in the range 1..nvars(basering).
- Return:
- int, 1 if the variables indexed by the entries of v form an
admissible subalgebra, 0 otherwise
Example:
| | LIB "ncpreim.lib";
ring r = 0,(e,f,h),dp;
matrix d[3][3];
d[1,2] = -h; d[1,3] = 2*e; d[2,3] = -2*f;
def A = nc_algebra(1,d);
setring A; A; // A is U(sl_2)
==> // coefficients: QQ
==> // number of vars : 3
==> // block 1 : ordering dp
==> // : names e f h
==> // block 2 : ordering C
==> // noncommutative relations:
==> // fe=ef-h
==> // he=eh+2e
==> // hf=fh-2f
// the subalgebra generated by e,f is not admissible since [e,f]=h
admissibleSub(1..2);
==> 0
// but the subalgebra generated by f,h is admissible since [f,h]=2f
admissibleSub(2..3);
==> 1
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