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Design #1738

Suggestion about Graded polynomial rings

Added by John Abbott 12 months ago. Updated 12 months ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
Data Structures
Target version:
CoCoALib-0.99880
Start date:
03 May 2023
Due date:
% Done:

10%

Estimated time:
Spent time:
0.50 h

Description

If the user creates a graded polynomial ring, maybe CoCoA could actually create 2 polynomial rings:
  • the one requested
  • a second one which homog maps into

The rings should know about each other so that homog and dehomog know where to map values to.

Is this a good idea? Or an unnecessary complication?

History

#1 Updated by John Abbott 12 months ago

In CoCoA a poly ring has default term-order degrevlex which we regard as 1-graded.
My suggestion means that by default two polynomial rings are created, which is a little wasteful. But if the second ring is never used, it will not be noticeably wasteful.

#2 Updated by Anna Maria Bigatti 12 months ago

  • % Done changed from 0 to 10

Sounds interesting: this is surely handy for "human handling".
Maybe the homogenizing ring could be created the first time homog is called?
(tricky, the ring should be mutable?)

I'm just undecided about one thing: we have to make some choices
  1. name of homogenizing indet (I suggest h)
  2. first or last? Matematically we add "x_0" as the new first indet, so that the indices of the other indets are left unchanged (also convenient for keeping DegRevLex), but for "automatic handling" this means the indices will be shifted by 1.

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