CGSigma: Casson-Gordon Signature Calculator

A Python script to compute Casson-Gordon sigma signatures of two-bridge knots using the formula from [CG1986, p. 188]. The formula expresses the signatures in terms of a weighted count of lattice points in a planar triangle determined by the knot.

The script can optionally generate plots of these triangles and their corresponding lattice points using matplotlib.

Example plot of triangle and lattice points, generated by the script.

References

[CG1986] Casson, A.J. and Gordon, C. McA., "Cobordism of Classical Knots", Progress in Mathematics, Vol. 62, pp. 181–199, 1986.

Source Code

For more details and to view the source code, please visit the GitHub repository.