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7.3.12 modulo (plural)
Syntax:
modulo ( ideal_expression, ideal_expression )
modulo ( module_expression, module_expression )
Type:
- module
Purpose:
modulo(h1,h2)
represents
, where
and are considered as submodules of the same free module
(s=1 for ideals).
Let
(resp. ) be the matrix of size (resp. ), having the
generators of (resp. )as columns.
Then
, where
is the induced map.
modulo(h1,h2) returns generators of
the kernel of this induced map.
Example:
| LIB "ncalg.lib";
def A = makeUsl2();
setring A; // this algebra is U(sl_2)
option(redSB);
option(redTail);
ideal I = e2,f2,h2-1;
I = twostd(I);
print(matrix(I)); // print I in a compact form
==> h2-1,fh-f,eh+e,f2,2ef-h-1,e2
ideal E = std(e);
ideal T = modulo(E,I);
T = NF(std(I+T),I);
T = std(T);
T;
==> T[1]=h-1
==> T[2]=e
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See also
syz (plural).
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