Automatically add generic encoders/decoders to any linear code class

[sagetrac-dlucas]

Some encoders/decoders (e.g. Syndrome decoders) are "generic" encoders/decoders which work for any linear code family.
This ticket implements a very small change which automatically add these generic decoders to any code family assuming one adds a line related to this encoder/decoder into AbstractLinearCode's constructor.
Before, one had to manually add one's encoder/decoder in any module which contains a linear code class.

CC: @johanrosenkilde

Component: coding theory

Author: David Lucas

Branch: 6d01e05

Reviewer: Johan Sebastian Rosenkilde Nielsen

Issue created by migration from https://trac.sagemath.org/ticket/20840

[sagetrac-dlucas]

Branch: u/dlucas/automatically_add_generic_encoders_and_decoders_to_any_linear_code

[sagetrac-dlucas]

comment:2

I implemented the feature described above.
I also added a dedicated note in the thematic tutorial which explains how to create new objects in sage/coding.

This is now open for review.

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New commits:

55f8771	Added automatic registration for generic encoder/decoders
550c584	Added a note to document this feature in related tutorial
ad1cadd	fixed broken doctest in the introductory tutorial

[sagetrac-dlucas]

Commit: ad1cadd

[sagetrac-dlucas]

Author: David Lucas

[johanrosenkilde]

comment:3

I don't think it makes sense to let all codes have ParityCheckEncoder, the reason being that for any code where the default encoder is something else, say A, then ParityCheckEncoder behaves exactly like SystematicEncoder.

This is because ParityCheckEncoder.generator_matrix calls
code.parity_check_matrix().right_kernel() which always returned a matrix in reduced row echelon form, i.e. the same systematic generator matrix that SystematicEncoder uses.

[sagetrac-dlucas]

comment:4

Good point. I made the suggested change and fixed doctests accordingly.
I also removed generic decoders from the list of imports in grs.py, hamming_code.py and punctured_code.py as they are no longer needed there.

David

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New commits:

8dc72f5	Parity check encoder is no longer systematically imported. Reinstated it in hamming_code.py
46485e6	Removed useless imports
6d01e05	Fixed broken doctests

[sagetrac-dlucas]

Changed commit from ad1cadd to 6d01e05

[johanrosenkilde]

comment:5

Looks good, green light. But found two unrelated small bugs in Sage while testing this ticket :-)

[johanrosenkilde]

Reviewer: Johan S. R. Nielsen

[vbraun]

Changed branch from u/dlucas/automatically_add_generic_encoders_and_decoders_to_any_linear_code to 6d01e05

[jdemeyer]

Changed reviewer from Johan S. R. Nielsen to Johan Sebastian Rosenkilde Nielsen

[jdemeyer]

Changed commit from 6d01e05 to none