Dear all, currently the sparse graph backend keeps a reversed copy of the graph.
However, the SparseGraph itself does not have access to it and thus the reversed structure should be moved there for obvious optimizations. See #28904 <https://trac.sagemath.org/ticket/28904>. As the sparse graph backend is the only backend actually using the reversed structure, it would make sense to remove this. However, it is very well possible that people use the unsafe methods of SparseGraph directly and code will break. E.g. in graphs/trees.py the undirected trees are generated by manually adding an arc in each direction. I think, if we remove the reversed graph attribute in CGraph altogether, people are more likely to catch on that something changed. But in an undirected graph it can very well happen that they add two edges instead of one (as they used to add one arc for each direction). Any thoughts? Jonathan -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/2964eb6e-e5d1-433e-9105-59952169c2db%40googlegroups.com.
