Opened 7 months ago

Last modified 6 months ago

#27828 new defect

Iterated polynomial quotient ring construction

Reported by: katestange Owned by:
Priority: minor Milestone:
Component: finite rings Keywords: quotient ring, polynomial ring, finite field, construction
Cc: katestange Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

In v7.3, the following nested polynomial ring construction returns NotImplementedError?:

q = 11
n = 4
F = GF(q)
rings = [ [F, F(-1)] ]
for i in range(1,n):
    lastring = rings[i-1]
    S.<x> = PolynomialRing(lastring[0], 'x');
    zetaname = 'z' + str(i); # z0 = -1, z1 = i, etc.
    R = S.quotient( x^2 - lastring[1], zetaname ) # take square root of last generator
    rings.append( [R, R.gen()] )

Here, changing n=4 to n=3 or changing q=11 to q=13 (or anything 1 mod 4) works fine.

On the other hand, in Sage v8.3, this now works for q=11 but is now broken (NotImplementedError?) for q=13.

So, clearly in v8.3, something from v7.3 got broken, and something got fixed.

However, this code really ought to work for all n and prime q.

Change History (2)

comment:1 Changed 6 months ago by embray

As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).

comment:2 Changed 6 months ago by embray

  • Milestone sage-8.8 deleted

As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).

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