As a part of my research I am working with intersection matrices of Heegaard diagrams. Is there some software that could help me compute such matrices for some examples?


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    $\begingroup$ Moira Chas has an applet to compute intersection numbers (although I couldn't get it to work on my laptop!): math.sunysb.edu/~moira $\endgroup$
    – Ian Agol
    Nov 1, 2013 at 22:06

1 Answer 1


Alden Walker's "branched" seems to have similar functionality to Moira Chas's programs mentioned by Ian Agol. It seems to work on my machine. Here is an excerpt from the branched README file:

Moira Chas (Stony Brook) has some Java applets on her web site http://www.math.sunysb.edu/~moira/ which compute self-intersections of a single loop on a surface with one boundary component. branched has been tested to agree with this applet on a bunch of inputs.

More broadly, Nathan Dunfield curates the website www.CompuTop.org that is probably the first place to look if the question is: "Is there software (in low dimensional topology) that does $blank$?"


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