Boundary slopes of Montesinos knots

Hatcher and Oertel in their paper Boundary slopes of Montesinos knots gave an algorithm for computing the boundary slopes of a given Montesinos knot. At the end of their paper, they provided a table which gave the boundary slopes for each knot of 10 or fewer crossings which is a Montesinos knot. Unfortunately, this table contains several errors. This page provides two things.

Important Note: Prior to January 2, 2008 this program contained a number of bugs. The current version is most likely correct. The below paper was revised with the new program in June 2010.


The paper is available from the arXiv, and was revised in June 2010.


The program can compute the boundary slopes of a two-bridge knot or Montesinos knot. The program is written in the programming language Python. You will need a Python interpreter (version 1.5 or newer) to run these programs. These are free and available for virtually every platform from the Python home page. If you're using UNIX, you can see if your system has python installed by typing which python (Linux systems almost always have Python installed). To install, download all the files below into the same directory (folder). Then do The program will then give you all the instructions you will need. Here are the files you'll need: For those using a command-line based operating system, such as UNIX, and prefer a command line version of, I offer: (instructions at the top of each file)

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