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2022-10-26 08:45:39 +0100 asked a question Isomorphism of planar graphs

Isomorphism of planar graphs Is there a way to check if two planar graphs (so plane graphs embedded in the 2-sphere) are

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2020-10-29 18:14:21 +0100 commented answer Generators of simplicial homology

This is perfect, thank a lot!

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2020-10-29 14:02:45 +0100 asked a question Generators of simplicial homology

I have this code to compute the homology of a simplicial complex

S = SimplicialComplex([[5, 2], [5, 2, 1], [5, 0], [5, 1], [4, 3], [4, 3, 0], [4, 2], [4, 0], [3, 0], [3, 1], [2, 1],])
S.homology(generators = True)

The output only consists of the homology, and does not contain the generators. Am I missing something?

2014-12-12 11:07:06 +0100 commented answer compiling problems with new versions

Thanks! This was really helpful!!

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2014-11-26 18:09:42 +0100 commented answer compiling problems with new versions

This does not seem to work either, and the same problem arises: the output on the sagenb site (and on the older version) is different from the one on the SMC (and on a 6.3 version on a VM). Which sort of details could be useful? The program basically just computes the homology of a complex and then does operations (such as computing Lefschetz polynomials) on the outputted homology groups.

2014-11-25 22:38:00 +0100 commented question compiling problems with new versions

@John It seems like both solutions do not solve my problem (but I am anyways really thankful for the efforts and the disturb caused!): I do not know in advance which degrees are going to be useful, and the sucessive computations are concerned with the whole outputted homology.

2014-11-25 16:55:24 +0100 commented question compiling problems with new versions

Thanks for the quick clarification! is there any possible known quick way to bypass the problem (I guess I could try to fix my problem somehow, but I would not like to create more mess if it is not necessary)

2014-11-25 16:23:16 +0100 commented question compiling problems with new versions

I tried to cut of the project a minimal case, but after some more debugging it seems that the problem is that the .homology() function of an acyclic chain complex is an empty dictionary, while according to the documentation it should be a dictionary containing the value 0 in the appropriate degrees. In other terms, i would like the output of: sage: D = ChainComplex({0: identity_matrix(ZZ, 4), 4: identity_matrix(ZZ, 30)}) sage: D.homology()

to be {0: 0, 1: 0, 4: 0, 5: 0}, while on cloud.sagemath it gives back just {}

2014-11-25 10:19:58 +0100 asked a question compiling problems with new versions

Hi, I've been developing a project on my university's computers (which unfortunately run a 4.7.1 version) and on the site, and everything went fine. But as soon as I tried to run the project on cloud.sagemath I ran into problems (like a "keyerror 0" message). After some work I think that these problems are somehow due to the .ngens() function, so I'd like to know if there are some known issues regarding versions update and/or with this particular function. thanks