Automorphisms of simplicial complexes

[chapoton]

It would be good to have a method to compute the automorphism group of a simplicial complex.

This patch implements that.

And also a procedure to check wether two simplicial complexes are isomorphic

[chapoton]

Better version, acting on vertices. Thanks, Nathann !

[chapoton]

It would be good to have a method to compute the automorphism group of a simplicial complex.

This patch implements that.

And also a procedure to check wether two simplicial complexes are isomorphic.

[ncohen]

Excellent ! Well, it seems good to go, it will certainly be useful eventually, and at the very least in #13888. Passes all tests, does its job :-)

Nathann

[jdemeyer]

Sphinx is unhappy:

/release/merger/sage-5.7.beta1/local/lib/python2.7/site-packages/sage/homology/simplicial_complex.py:docstring of sage.homology.simplicial_complex:3: WARNING: Bullet list ends without a blank line; unexpected unindent.

[chapoton]

I think I have corrected the sphinx issue in the new patch.

[ncohen]

Just checked again, and there's no warning... Sorry for that ^^;

Nathann

[jdemeyer]

On rosemary (RHEL 5.6 x86_64):

sage -t  --long -force_lib devel/sage/sage/homology/simplicial_complex.py
**********************************************************************
File "/home/buildbot/build/sage/rosemary-1/rosemary_full/build/sage-5.7.beta1/devel/sage-main/sage/homology/simplicial_complex.py", line 2914:
    sage: Z1.is_isomorphic(Z2, certify=True)
Expected:
    (True, {'a': 't', 1: 'e', 2: 4, 3: 'r'})
Got:
    (True, {'a': 'r', 2: 4, 3: 't', 1: 'e'})
**********************************************************************
File "/home/buildbot/build/sage/rosemary-1/rosemary_full/build/sage-5.7.beta1/devel/sage-main/sage/homology/simplicial_complex.py", line 2972:
    sage: Z.automorphism_group()
Expected:
    Permutation Group with generators [(3,4)]
Got:
    Permutation Group with generators [(1,4)]
**********************************************************************
File "/home/buildbot/build/sage/rosemary-1/rosemary_full/build/sage-5.7.beta1/devel/sage-main/sage/homology/simplicial_complex.py", line 2974:
    sage: Z.automorphism_group(translation=True)
Expected:
    (Permutation Group with generators [(3,4)], {'a': 4, 1: 1, 2: 2, 3: 3})
Got:
    (Permutation Group with generators [(1,4)], {'a': 1, 1: 2, 2: 3, 3: 4})
**********************************************************************

[chapoton]

I have tried to make more intrinsic doctests, and I hope they will pass.

[chapoton]

new patch, with good tests

[ncohen]

Well, it looks good to me again. The first dictionary in the doctests should not be a problem as the hash function of an integer is the integer itself, and the other tests are now isomorphism tests, returning True/False?.

Sooooooooo I guess it's good to go again !

Nathann