Module ++ Module -- direct sum of modules

Synopsis

• Operator: ++

Description

i1 : R = ZZ/101[a..c];

i2 : image vars R ++ kernel vars R

o2 = image {0} | a b c 0  0  0  |
           {1} | 0 0 0 -b 0  -c |
           {1} | 0 0 0 a  -c 0  |
           {1} | 0 0 0 0  b  a  |

                             4
o2 : R-module, submodule of R

The projection and inclusion maps for direct sums can be obtained with the following methods.

• Module ^ Array -- projection onto summand
• Module _ Array -- inclusion from summand

The components can be recovered later with components or with formation.

See also

• directSum -- direct sum of modules or maps