Feature #1283: Printing for (prime) finite fields - CoCoALib - CoCoA Project

Feature #1283

Printing for (prime) finite fields

Added by John Abbott almost 5 years ago. Updated over 4 years ago.

Status:

Closed

Priority:

Normal

Assignee:

John Abbott

Category:

Improving

Target version:

CoCoALib-0.99650 November 2019

Start date:

11 May 2019

Due date:

% Done:

100%

Estimated time:

1.01 h

Spent time:

1.00 h

Description

I have found a "useful" result in an old file.
Unfortunately the result contains printed forms of the RingHoms used rather than the characteristic of codomain (which is the useful information). A typical entry is:

RingHom(RingWithID(677, "ZZ[x]") --> RingWithID(550, "RingWithID(382)[x]") sending (x |--> x))

Great! So what is the characteristic?

I suggest that (small) prime finite fields print out in a better way when appearing as coeff rings.

Related issues

History

#1 Updated by John Abbott almost 5 years ago

Consider the following session:

/**/ P ::= ZZ/(5)[x];
/**/ println P;
RingWithID(4, "RingWithID(3)[x]")
/**/ CoeffRing(P);
RingWithID(3, "FFp(5)")

Frankly RingWithID(3)[x] is pretty meaningless to the reader.
Surely FFp(5)[x] is more helpful!

What do you think? Should I change the printing?

Note: to be honest I find the RingID almost never helpful (but it almost always printed)

#2 Updated by John Abbott almost 5 years ago

Status changed from New to In Progress
% Done changed from 0 to 10

I am aware that in CoCoALib one can create two rings which are essentially "identical", but are not considered as being the same by CoCoALib. An easy example is to create QQ[x] twice. The rings are plainly the same (even same term-ordering), but CoCoALib regards them as distinct, so "mixed ring" errors can easily arise. The user may be puzzled if they print out the same; hence the idea of making the printed form also print the RingID...

However the current approach is quite inconvenient and rather unnatural, so I think we need a better solution. But what? And how?