Singular

5.1.119 prune

Syntax:

prune ( module_expression )

Type:

module

Purpose:

returns the module minimally embedded in a free module such that the corresponding factor modules are isomorphic.

Note:

If for the input module the attribute "isHomog" is set, prune also sets the attribute "isHomog".
For non-global orderings, only reduction steps with constant units are performed. Hence, the returned module does not need to be minimal.

Example:

ring r=0,(x,y,z),dp; module m=gen(1),gen(3),[x,y,0,z],[x+y,0,0,0,1]; print(m); ==> 1,0,x,x+y, ==> 0,0,y,0, ==> 0,1,0,0, ==> 0,0,z,0, ==> 0,0,0,1 print(prune(m)); ==> y, ==> z