torsionSubmodule -- create the torsion submodule of a module

Synopsis

• Usage:

  torsionSubmodule( M1 )

• Inputs:
  • M1, a module
• Optional inputs:
  • Strategy => a symbol, default value NoStrategy, specify a strategy for the internal call to reflexify
  • KnownDomain => a Boolean value, default value false, assume the ambient ring is a domain for the internal call to reflexify
• Outputs:
  • a module

Description

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

• reflexify -- calculate the double dual of an ideal or module Hom(Hom(M, R), R)