Feature #1072
syz: apply to ModuleElem?
Status:
Rejected
Priority:
Normal
Assignee:
Category:
enhancing/improving
Target version:
Description
Would it make sense to allow syz to be applied to a ModuleElem?
use P ::= QQ[x,y,z]; M3 := NewFreeModule(P,3); v := ModuleElem(M3, [0,z,-y]); syz(v); --> ERROR
Related issues
History
#1
Updated by John Abbott almost 7 years ago
Updated by The current solution is to do the following:
use P ::= QQ[x,y,z]; M3 := NewFreeModule(P,3); v := ModuleElem(M3, [0,z,-y]); /// syz(v); --> ERROR S := submodule(M3, [v]); syz(S);
Note that even to create a mono-generator ("cyclic") submodule it is necessary to put the generator inside a list.
#2
Updated by John Abbott almost 7 years ago
The man page still calls th fn Syz with a capital S; it should be syz, shouldn't it?
#3
Updated by John Abbott almost 7 years ago
Is it right that syz should give error if one of the coords is zero?
use P ::= QQ[x,y,z]; syz([0,x,y]); --> ERROR: Non-zero RingElem required
Shouldn't the answer be [[1,0,0],[0,y,-x]]?
#4
Updated by Anna Maria Bigatti about 1 month ago
Updated by - Status changed from New to Resolved
- Target version changed from CoCoA-5.?.? to CoCoA-5.4.2
- % Done changed from 0 to 80
I'm inclined to reject this.
It would be ambiguos: syz of the components, or of the cyclic module it generates?
#5
Updated by Anna Maria Bigatti about 1 month ago
- Related to Feature #1206: syz, SyzOfGens: which shifts for zero? added
#6
Updated by Anna Maria Bigatti about 1 month ago
- Status changed from Resolved to Rejected
- Assignee set to Anna Maria Bigatti
- % Done changed from 80 to 100
- Estimated time set to 1.01 h
#7
Updated by John Abbott about 1 month ago
Agreed that we should reject.