Top
Back: preimageNC
Forward: isUpperTriangular
FastBack:
FastForward:
Up: ncpreim_lib
Top: Singular Manual
Contents: Table of Contents
Index: Index
About: About this document
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


Top Back: preimageNC Forward: isUpperTriangular FastBack: FastForward: Up: ncpreim_lib Top: Singular Manual Contents: Table of Contents Index: Index About: About this document
            User manual for Singular version 4.3.1, 2022, generated by texi2html.