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D.5.8.10 nf_icis
Procedure from library sing.lib (see sing_lib).
- Usage:
nf_icis(i); i ideal
- Return:
ideal = generic linear combination of generators of i if i is an ICIS (isolated complete intersection singularity), return i if not
- Note:
this proc is useful in connection with proc milnor
printlevel >=0: display comments (default)
Example:
LIB "sing.lib"; int p = printlevel; printlevel = 1; ring r = 32003,(x,y,z),ds; ideal i = x3+y4,z4+yx; nf_icis(i); → // complete intersection of dim 1 → // dim-sequence: → // dim of singular locus = 0 → // isolated singularity if last number is 0 in dim-sequence: → // dim of singular locus = 0 → // isolated singularity if last number is 0 in dim-sequence: → // ICIS in generic form after 1 genericity loop(s) → _[1]=2xy+x3+y4+2z4 → _[2]=xy+z4 ideal j = x3+y4,xy,yz; nf_icis(j); → // no complete intersection → // dim-sequence: → // no complete intersection → _[1]=x3+y4 → _[2]=xy → _[3]=yz printlevel = p; |