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Divisor :: torsionSubmodule

torsionSubmodule -- create the torsion submodule of a module

Synopsis

Description

Finds the torsion submodule of a module. It does this by computing the kernel of the map from M1 to its reflexification. The options Strategy and KnownDomain are passed along when the function reflexify is called.

i1 : R = QQ[x,y];
i2 : m = ideal(x,y);

o2 : Ideal of R
i3 : M = (R^1/m) ++ R^1

o3 = cokernel | x y |
              | 0 0 |

                            2
o3 : R-module, quotient of R
i4 : prune torsionSubmodule M

o4 = cokernel | y x |

                            1
o4 : R-module, quotient of R

See also

Ways to use torsionSubmodule :

For the programmer

The object torsionSubmodule is a method function with options.