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7.10.4.10 lieBracket
Procedure from library freegb.lib (see freegb_lib).
- Usage:
- lieBracket(a,b[,N]); a,b letterplace polynomials, N an optional integer
- Return:
- poly
- Assume:
- basering has a letterplace ring structure
- Purpose:
- compute the Lie bracket [a,b] = ab - ba between letterplace polynomials
- Note:
- if N>1 is specified, then the left normed bracket [a,[...[a,b]]]] is
computed.
Example:
| | LIB "freegb.lib";
ring r = 0,(x,y),dp;
ring R = freeAlgebra(r, 4);
poly a = x*y; poly b = y;
lieBracket(a,b);
==> -y*x*y+x*y*y
lieBracket(x,y,2);
==> y*x*x-2*x*y*x+x*x*y
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