Hi Bruce,

> I have implemented ribbon graphs (aka planar diagrams)
> This is in the repository
>
> https://bitbucket.org/Bruce_Westbury
>
> [...]

I'm working on surface dynamics and need ribbon graphs at different
places. I have an implementation of ribbon graphs which store only
three permutations (as in the book of Lando and Zvonkine "Graphs on
Surfaces and Their Applications"). Actually they are "partial"
permutations (the domain need not be [0,...,n-1] but each permutation
is a list of n elements). More generally, they consider
constellations, which are n-tuples of permutations with the condition
that their product is the identity.

But, at the difference from yours, what I call a ribbon graph is not
necessarily planar (it has a genus) which seems to be standard. It
seems that you are interested in what I would call "ribbon graph of
genus 0" ?

I download your code but it is not clear at all for me what can I do
with it... Could you try to put more examples or explanations ? In
particular the definition of a ribbon graph. And also, what do you
intend to do with your code ?

The part which deals with embedding should be very useful.

I have more technical comments after the reading of your code, but I
first would like to know what are your mathematical and programming
motivations.

Best,
Vincent

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