Project

General

Profile

Design #970

Weights in ElimMat?

Added by Anna Maria Bigatti over 7 years ago. Updated over 7 years ago.

Status:
In Progress
Priority:
Normal
Assignee:
-
Category:
Improving
Target version:
CoCoALib-1.0
Start date:
11 Nov 2016
Due date:
% Done:

10%

Estimated time:
Spent time:
0.30 h

Description

(similar for ElimHomogMat)
What should ElimMat([2,3], mat([[1,5,2]])); return? (now it is (a))

(a) [0, 1, 1],
    [1, 5, 2],
    [0, 0, -1]
(b)            [0, 5, 2],
               [1, 5, 2],
               [0, 0, -1]
(c) [0, 5, 2],
    [1, 0, 0],
    [0, 0, -1]

History

#1 Updated by John Abbott over 7 years ago

I prefer (c) to (b) perhaps because it is sparser.

(a) and (c) clearly do not give the same term-ordering though they are both clearly elimination orderings for indets 2 and 3.

What will you do if the weights are not given by a single row?
Case (a) clearly extends to any weights matrix; it is not so clear to me how to extend the other approach (just take first non-zero entry in the corresponding column?)

#2 Updated by John Abbott over 7 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 10
I suggest proceeding with definition (a):
  • it is already implemented
  • it is easy to explain/describe

If we come across an application where definition (a) is inappropriate then we can consider an alternative definition inspired by that application.

Also available in: Atom PDF