Geodesic
COMPUTING WITH SUBGROUPS OF THE MODULAR GROUP
Glasgow mathematical journal, Tome 57 (2015) no. 1, pp. 173-180

Voir la notice de l'article provenant de la source Cambridge University Press

We give several algorithms for finitely generated subgroups of the modular group PSL2(Z) given by sets of generators. First, we present an algorithm to check whether a finitely generated subgroup H has finite index in the full modular group. Then we discuss how to parametrise the right cosets of H in PSL2(Z), whether the index is finite or not. Further, we explain how an element in H can be written as a word in a given set of generators of H.
DOI : 10.1017/S0017089514000202
Mots-clés : 20-04, 20H05 
KIRSCHMER, MARKUS; LEEDHAM-GREEN, CHARLES. COMPUTING WITH SUBGROUPS OF THE MODULAR GROUP. Glasgow mathematical journal, Tome 57 (2015) no. 1, pp. 173-180. doi: 10.1017/S0017089514000202
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