4 Ring Maps
  
  
  4.1 Ring Maps: Attributes
  
  4.1-1 KernelSubobject
  
  KernelSubobject( phi )  attribute
  Returns:  a homalg submodule
  
  The kernel ideal of the ring map phi.
  
  4.1-2 KernelEmb
  
  KernelEmb( phi )  attribute
  Returns:  a homalg map
  
  The  embedding  of  the  kernel ideal Kernel(phi) into the Source(phi), both
  viewed as modules over the ring R :=Source(phi) (cf. Kernel (4.2-1)).
  
  
  4.2 Ring Maps: Operations and Functions
  
  4.2-1 Kernel
  
  Kernel( phi )  method
  Returns:  a homalg module
  
  The kernel ideal of the ring map phi as an abstract module.