# Ptolemy coordinates, Dehn invariant and the A-polynomial

@article{Zickert2014PtolemyCD,
title={Ptolemy coordinates, Dehn invariant and the A-polynomial},
author={Christian K. Zickert},
journal={Mathematische Zeitschrift},
year={2014},
volume={283},
pages={515-537}
}
• C. Zickert
• Published 30 April 2014
• Mathematics
• Mathematische Zeitschrift
We define Ptolemy coordinates for representations that are not necessarily boundary-unipotent. This gives rise to a new algorithm for computing the $${{\mathrm{SL}}}(2,{\mathbb {C}})\;A$$SL(2,C)A-polynomial, and more generally the $${{\mathrm{SL}}}(n,{\mathbb {C}})\;A$$SL(n,C)A-varieties. We also give a formula for the Dehn invariant of an $${{\mathrm{SL}}}(n,{\mathbb {C}})$$SL(n,C)-representation.

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