The classical modular group as a subgroup of GL(2, Z)†
Glasgow mathematical journal, Tome 26 (1985), pp. 161-164
Voir la notice de l'article provenant de la source Cambridge University Press
The title is somewhat misleading, since the classical modular group Г= PSL(2, Z) is certainly not a subgroup of GL(2, Z). What is meant of course are the faithful representations of F as a subgroup of GL(2, Z), where Г is to be thought of as the free product of a cyclic group of order 2 and a cyclic group of order 3. No such representation is possible as a subgroup of SL(2, Z); it is necessary to have matrices of determinant −1 as well.
Newman, Morris. The classical modular group as a subgroup of GL(2, Z)†. Glasgow mathematical journal, Tome 26 (1985), pp. 161-164. doi: 10.1017/S0017089500006157
@article{10_1017_S0017089500006157,
author = {Newman, Morris},
title = {The classical modular group as a subgroup of {GL(2,} {Z){\textdagger}}},
journal = {Glasgow mathematical journal},
pages = {161--164},
year = {1985},
volume = {26},
doi = {10.1017/S0017089500006157},
url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500006157/}
}
[1] 1.Newman, M., Some free products of cyclic groups, Michigan Math. J. 9 (1962), 369–373. Google Scholar | DOI
[2] 2.Newman, M., Integral Matrices (Academic Press, 1972). Google Scholar
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