5.1.123 prune_map

Syntax:

prune_map( module_expression , smatrix_name )

Type:

module

Purpose:

returns the module minimally embedded in a free module such that the corresponding factor modules are isomorphic together with the map (as matrix)

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]; smatrix M; 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_map(m,M)); // pruned module ==> v[1]:1 v[2]:1 v[3]:2 v[4]:2 v[5]:3 ==> y, ==> z print(m*M); // apply map ==> 0, ==> y, ==> 0, ==> z, ==> 0 print(M); // map ==> -x, ==> 0, ==> 1, ==> 0