Please help with #23967 Coercion pushout for FGP_modules

[Simon Brandhorst]

Would someone please guide me through this?
I would like to learn now to implement such a thing in sage. Yet I wouldn't know where to start here.
It is mathematically quite simple.

[Simon King]

Does http://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html help?

Cheers,
Simon

[Simon Brandhorst]

Thank you Simon :).
Probably, it will take me some time to read/understand though.
Would you review the ticket when it is done?

[Simon Brandhorst]

It helps a bit. Though my problem right now is that fgp_modules do not have a construction defined in the tutorial this is the case. So I have to give fgp_modules a construction functor? Or is there an easier way to get a pushout?

On Monday, October 9, 2017 at 12:45:17 PM UTC+2, Simon King wrote:

[David Roe]

On Mon, Oct 9, 2017 at 1:38 PM, Simon Brandhorst <sbran...@web.de> wrote:

It helps a bit. Though my problem right now is that fgp_modules do not have a construction defined in the tutorial this is the case. So I have to give fgp_modules a construction functor? Or is there an easier way to get a pushout?

Nope, that's how you get pushouts.  You can take a look at the QuotientFunctor in sage/categories/pushout.py for inspiration.

David

On Monday, October 9, 2017 at 12:45:17 PM UTC+2, Simon King wrote:

On 2017-10-09, Simon Brandhorst <sbran...@web.de> wrote:
> Would someone please guide me through this?
> I would like to learn now to implement such a thing in sage. Yet I wouldn't
> know where to start here.
> It is mathematically quite simple.

Does http://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html help?

Cheers,
Simon

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[Simon Brandhorst]

I see. I have found an easy solution by defining a method ._pushout_
It works. I have uploaded the branch so you can take a look.

On Monday, October 9, 2017 at 7:55:13 PM UTC+2, David Roe wrote:

On Mon, Oct 9, 2017 at 1:38 PM, Simon Brandhorst <sbran...@web.de> wrote:

It helps a bit. Though my problem right now is that fgp_modules do not have a construction defined in the tutorial this is the case. So I have to give fgp_modules a construction functor? Or is there an easier way to get a pushout?

Nope, that's how you get pushouts.  You can take a look at the QuotientFunctor in sage/categories/pushout.py for inspiration.

David

On Monday, October 9, 2017 at 12:45:17 PM UTC+2, Simon King wrote:

On 2017-10-09, Simon Brandhorst <sbran...@web.de> wrote:
> Would someone please guide me through this?
> I would like to learn now to implement such a thing in sage. Yet I wouldn't
> know where to start here.
> It is mathematically quite simple.

Does http://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html help?

Cheers,
Simon

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[Simon Brandhorst]

OK I have implemented the less easy version with construction functors. That seems to be the best practice. The ticket is ready for review.

On Monday, October 9, 2017 at 7:55:13 PM UTC+2, David Roe wrote:

On Mon, Oct 9, 2017 at 1:38 PM, Simon Brandhorst <sbran...@web.de> wrote:

It helps a bit. Though my problem right now is that fgp_modules do not have a construction defined in the tutorial this is the case. So I have to give fgp_modules a construction functor? Or is there an easier way to get a pushout?

Nope, that's how you get pushouts.  You can take a look at the QuotientFunctor in sage/categories/pushout.py for inspiration.

David

On Monday, October 9, 2017 at 12:45:17 PM UTC+2, Simon King wrote:

On 2017-10-09, Simon Brandhorst <sbran...@web.de> wrote:
> Would someone please guide me through this?
> I would like to learn now to implement such a thing in sage. Yet I wouldn't
> know where to start here.
> It is mathematically quite simple.

Does http://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html help?

Cheers,
Simon

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