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7.7.10.0. AltVarStart
Procedure from library nctools.lib (see nctools_lib).
- Usage:
- AltVarStart();
- Return:
- int
- Purpose:
- returns the number of the first alternating variable of basering
- Note:
- basering should be a super-commutative algebra with at most one block of anti-commutative variables
For commutative rings, nvars(basering)+1 will be returned.
Example:
| LIB "nctools.lib";
ring R = 0,(x(1..4)),dp; // global!
def ER = superCommutative(2); // (b = 2, e = N)
setring ER; ER;
==> // characteristic : 0
==> // number of vars : 4
==> // block 1 : ordering dp
==> // : names x(1) x(2) x(3) x(4)
==> // block 2 : ordering C
==> // noncommutative relations:
==> // x(3)x(2)=-x(2)*x(3)
==> // x(4)x(2)=-x(2)*x(4)
==> // x(4)x(3)=-x(3)*x(4)
==> // quotient ring from ideal
==> _[1]=x(4)^2
==> _[2]=x(3)^2
==> _[3]=x(2)^2
"Alternating variables: [", AltVarStart(), ",", AltVarEnd(), "].";
==> Alternating variables: [ 2 , 4 ].
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