Checking if two fans have the same support

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MattLarson
Posts: 13
Joined: 03 Jun 2018, 22:57

Checking if two fans have the same support

Postby MattLarson » 21 Jul 2021, 19:55

Hi,

Is there a way to check if two fans have the same support?

The fans I am interested are pure and full-dimensional.

One could take a common refinement, and then check if both fans are subdivisions of the common refinement. But I don't know how to check if one fan is a subdivision of another either.

Thank you!

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joswig
Main Author
Posts: 250
Joined: 24 Dec 2010, 11:10

Re: Checking if two fans have the same support

Postby joswig » 27 Jul 2021, 12:19

Indeed, currently polymake does not have such a function. Of course, it is absolutely desirable.

We started to discuss the matter within the developer's team. There are several ways to implement this, all of which are computationally costly, except for small fans in very low dimensions.

We are in the middle of putting together the roadmap for the next release. We might be able to add at least a proof of concept implementation.

I'll come back with more details next week. Please stay tuned.

lkastner
Developer
Posts: 11
Joined: 27 May 2012, 23:35

Re: Checking if two fans have the same support

Postby lkastner » 10 Sep 2021, 22:58

Since we are still figuring out the details of our final implementation, I made posted a jupyter notebook that should do the trick for small examples:
https://github.com/lkastner/jupyter-not ... t_pm.ipynb

There might still be boundary cases missing. Also note that this is really a brute force approach that is likely to fail for large examples. Let me know if anything is unclear.

MattLarson
Posts: 13
Joined: 03 Jun 2018, 22:57

Re: Checking if two fans have the same support

Postby MattLarson » 13 Sep 2021, 04:27

That works for my purposes, thank you!


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