[igraph] trees

[Keith Paton]

Hello igraph,

I am interested in how to draw a tree, as discussed below. Who can help?

Thanks,

Keith Paton

Independent researcher

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A tree is a connected graph without cycles; it can be drawn in the plane in many different ways. Somewhat remarkably, the drawings of all the trees with up to ten nodes published by Harary and by Schlick are remarkably similar; the former were drawn by Harary’s artist, the latter by the program Python.igraph.

How does that come about? Harary wrote in 1969 so did not have access to Python.igraph. What rules are used by Python.igraph and how does it come about that the drawings it generates are identicalto those in Haray, even down to the five cases where IMHO both systems make a mistake and draw the tree wrongly.

Harary F (1969) Graph Theory Chapman & Hall

Tamar Schlick runs the RNA research group at NYU. Her group maintains a database of trees with up to ten nodes, all drawn by Python.igraph