Let \funnyGamma be a torsion-free finite-index subgroup of \SL_{n} (\Z ) or \GL_{n} (\Z ), and let \nu be the cohomological dimension of \funnyGamma . We present an algorithm to compute the eigenvalues of the Hecke operators on H^{\nu -1} (\funnyGamma ;\Z ), for n= 2, 3, and 4. In addition, we describe a modification of the modular symbol algorithm of Ash and Rudolph for computing Hecke eigenvalues on H^{\nu } (\funnyGamma ;\Z ).
@article{1045604670,
author = {Gunnells, Paul E.},
title = {Computing Hecke eigenvalues below the cohomological dimension},
journal = {Experiment. Math.},
volume = {9},
number = {3},
year = {2000},
pages = { 351-367},
language = {en},
url = {http://dml.mathdoc.fr/item/1045604670}
}
Gunnells, Paul E. Computing Hecke eigenvalues below the cohomological dimension. Experiment. Math., Tome 9 (2000) no. 3, pp. 351-367. http://gdmltest.u-ga.fr/item/1045604670/