2021-04-09 13:33:48 +0200 | answered a question | RecursionError long lists I have found the problem. Sorry for wasting your time everyone. The lists themselves were not too long. There was a frea |

2021-04-09 05:53:19 +0200 | asked a question | RecursionError long lists RecursionError long lists I am working with long lists, and getting the error "RecursionError: maximum recursion depth e |

2021-04-05 07:54:18 +0200 | commented answer | simplifying a simplicial set I am relieved, that sounds much faster than I had expected!! I am fixing up an error I make labelling and enumerating si |

2021-04-04 07:08:59 +0200 | commented answer | simplifying a simplicial set Thanks very much for your help! My problem is with the large number of 4- and 5- dimensional simplices; there are not ne |

2021-04-03 10:21:48 +0200 | asked a question | simplifying a simplicial set simplifying a simplicial set The starting point to this question is a simplicial set with a large number of simplices. S |

2021-03-26 11:38:00 +0200 | commented answer | Constructing words or strings using iteration Thanks Sam |

2021-03-26 11:37:45 +0200 | marked best answer | Constructing words or strings using iteration It is not allowed to label simplices with numbers or lists, and I want to enter a few thousand simplices. I am therefore trying to do something that naively looks like this: I have also tried using strings. Does anyone know how to do this? |

2021-03-26 09:42:43 +0200 | asked a question | Constructing words or strings using iteration Constructing words or strings using iteration It is not allowed to label simplices with numbers or lists, and I want to |

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2021-02-24 03:41:48 +0200 | commented answer | alternative to jupyter notebook? I haven't got jupyterlab working yet, but yes, I do have thousands of lines. If everything works out, I will want to put the results into a .tex file Long term this definitely sounds like what I need. Thanks. |

2021-02-24 03:15:27 +0200 | commented question | alternative to jupyter notebook? Thanks, saving does help. I have no understanding of this process; why most of my stuff can be saved individually but is not saved when I save the session, or the ipynb file. For the moment, as long as it works. I've started on a newer computer, with more RAM, which also helps with some of the issues. Learning Linux will have to wait until we get IT support :-) |

2021-02-23 06:11:34 +0200 | asked a question | alternative to jupyter notebook? I have a number of problems using Jupyter notebook, windows 10. When my .ipynb file reaches a certain length, sage basically grinds to a halt, and I need to start a new file. When doing a long calculation, where each bit needs the calculations from the previous part, this isn't practical. Also, when I "save" an .ipynb file, the actual calculations aren't saved, and each file takes about half a day to go through and recalculate everything again. I have about 5 files now, and the power keeps flickering on and off briefly... Also, it happens constantly that sage won't let me type anything in. This can last for up to 10 minutes at a time, and seems to have something to do with the way the file is saved. I haven't even reached the final part of my calculation, which is the part I expect to be the slowest by far. My husband tells me to stop messing around with windows and learn Linux. Any other suggestions? Thanks very much! |

2021-02-10 12:37:36 +0200 | commented answer | cell complexes vs simplicial complexes Thanks, both of you, for confirming what I was beginning to be afraid of. I don't know how to describe continuous functions in sage, but for all the examples I can think of, the maps can be described as being piecewise linear. |

2021-02-09 11:56:32 +0200 | received badge | ● Nice Question (source) |

2021-02-09 08:02:06 +0200 | commented answer | Polyhedra, facets and vertices Thanks a lot John, I should have realised that. |

2021-02-09 06:41:25 +0200 | asked a question | cell complexes vs simplicial complexes I have spent several days googling, but am not able to find any basic information for working with cell complexes in sage. I am using windows 10 , sage 9.1 where the help function doesn't work. What I need to be able to do is to enter a cell complex, add cells, delete cells and subdivide. I already have functions defined that could be used to specify the gluing maps. There seems to be slightly more information available for working with simplicial complexes. If I were to subdivide my cell complex, I would get a simplicial complex; there are no exotic gluing maps. However, because the cells are high dimensional, the number of simplicies is huge after subdivision, and I am not sure I could correctly enter all that information by hand. Any suggestions would be very appreciated! If anyone has a file to share in which they have worked with cell complexes or simplicial complexes, that would also be really helpful to me to learn the syntax. |

2021-02-08 04:19:45 +0200 | commented answer | Polyhedra, facets and vertices Ah, ok. It would be best if I could share the ipynb file, but I can't put anything on my website without help from someone who speaks Chinese, and everyone is on holiday for the new year celebrations. Cocalc wants a lot of money for me to share files. P1=Polyhedron(ieqs=Lconstraints, base_ring=QQ) I've put the list Lconstraints here: https://pastebin.com/Uc8ANHcv When I enter P1.faces(5).vertices() or P1.faces(5).vertices_list() I get the error AttributeError: 'tuple' object has no attribute 'vertices' Thanks a lot everyone! |

2021-02-07 04:24:22 +0200 | commented answer | Polyhedra, facets and vertices Is there some way I can upload a file? The list of constraints used to define the polyhedron is too big to fit here. |

2021-02-06 12:05:50 +0200 | answered a question | Polyhedra, facets and vertices Thanks! When I changed to QQ, the two spurious 6-dimensional faces disappeared. However, now I get the error message "AttributeError: 'tuple' object has no attribute 'vertices'" for P1.faces(5)[0].vertices() as well as for P1.faces(5)[0].vertices_list() |

2021-02-06 10:10:56 +0200 | asked a question | Polyhedra, facets and vertices I have a 6-dimensional, convex, compact polyhedron in $\mathbb{R}^{12}$, that I am calling How can there be two 6-dimensional faces, each with a different number of vertices,
on the boundary of Also, when I try to find a list of vertices on the boundary of any 5-dimensional face of I get an error message However, My second question is, how do I get a list of vertices on the boundary of an $n$-dimensional face? |

2020-12-08 11:09:49 +0200 | commented answer | copying lists, embedded multigraphs Thanks heaps!!! |

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2020-12-08 03:34:24 +0200 | asked a question | copying lists, embedded multigraphs I am working with planar, embedded, labelled multigraphs.
I am trying to define a function Here, Thanks a lot for your help! |

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2020-11-30 10:16:09 +0200 | asked a question | 'method' object is not subscriptable Starting with a graph G, I would like to make a list, the ith element of which is the graph G with its ith edge deleted. When I enter the definition above, or a variation of it, I get the error 'method' object is not subscriptable Thanks a lot for any suggestions! |

2020-11-16 04:59:24 +0200 | commented question | Using ? for help in version 9.1 I have exactly the same problem. Also using sage 9.1, windows 10, Jupyter notebook. |

2020-11-11 02:56:22 +0200 | commented question | set_embedding when the embedding is not unique Thanks. That works now! |

2020-11-10 10:30:59 +0200 | asked a question | set_embedding when the embedding is not unique My planar graphs are not uniquely embeddable. The embedding found by sage is not the one I want, and I'm having trouble setting another one. Thanks for any help!!! |

2020-11-10 10:30:58 +0200 | answered a question | get graph combinatorial embedding from position of vertices I am also having trouble with set_embedding. My Graph does not have a unique planar embedding, and I would like to set the embedding to a different one from that found by sage. sage: D3half2=Graph({0:{1:'x2', 2:'x8', 3:'x9', 4:'x5'}, 1:{2:'x3'}, 2:{3:'x6', 4:'x4'}, 3:{4:'x12', 5:'x10'}, 4:{5:'x11'}}) sage: D3half2.is_planar() True sage:D3half2.is_planar(set_embedding=True) D3half2.set_embedding({0:{1, 4, 3, 2}, 1:{2, 0}, 2:{1, 0, 3, 4}, 3:{2, 0, 4, 5}, 4:{2, 5, 3, 0}}) ValueError Traceback (most recent call last) <ipython-input-11-78d1277ebcd7> in <module>() ----> 1 D3half2.set_embedding({Integer(0):{Integer(1), Integer(4), Integer(3), Integer(2)}, Integer(1):{Integer(2), Integer(0)}, Integer(2):{Integer(1), Integer(0), Integer(3), Integer(4)}, Integer(3):{Integer(2), Integer(0), Integer(4), Integer(5)}, Integer(4):{Integer(2), Integer(5), Integer(3), Integer(0)}}) /opt/sagemath-9.1/local/lib/python3.7/site-packages/sage/graphs/generic_graph.py in set_embedding(self, embedding) 2501 ValueError: vertices in ['s'] from the embedding do not belong to the graph 2502 """ -> 2503 self._check_embedding_validity(embedding, boolean=False) 2504 self._embedding = embedding 2505 /opt/sagemath-9.1/local/lib/python3.7/site-packages/sage/graphs/generic_graph.py in _check_embedding_validity(self, embedding, boolean) 2589 raise ValueError("vertices in {} from the embedding do not belong to the graph".format(list(set(embedding).difference(self)))) 2590 else: -> 2591 raise ValueError("vertices in {} have no corresponding entry in the embedding".format(list(set(self).difference(embedding)))) 2592 2593 if self._directed: ValueError: vertices in [5] have no corresponding entry in the embedding Thanks for any help!!!! |

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