++ -- a binary operator, usually used for direct sum

This operator may be used as a binary operator in an expression like x ++ y. The user may install binary methods for handling such expressions with code such as

              X ++ Y := (x,y) -> ...

where X is the class of x and Y is the class of y.

Methods for ++ :

ChainComplex ++ ChainComplex -- direct sum

ChainComplexMap ++ ChainComplexMap

CoherentSheaf ++ CoherentSheaf -- direct sum of coherent sheaves

GradedModule ++ GradedModule

GradedModule ++ Module

GradedModuleMap ++ GradedModuleMap

Matrix ++ Matrix -- direct sum of maps

Matrix ++ RingElement

Matrix ++ ZZ

Module ++ GradedModule

Module ++ Module -- direct sum of modules

Option ++ Option

RingElement ++ Matrix

RingElement ++ RingElement

RingElement ++ ZZ

Set ++ Set -- disjoint union of sets

ZZ ++ Matrix

ZZ ++ RingElement