SUBGROUPS OF FINITE INDEX IN (2, 3, n)-TRIANGLE GROUPS
Glasgow mathematical journal, Tome 54 (2012) no. 3, pp. 693-714
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For an integer n ≥ 7, let Δ(n) denote the (2, 3, n)-triangle group, and let M(n) be the positive integer determined by the conditions that Δ(n) has a subgroup of index m for all m ≥ M(n), but no subgroup of index M(n) − 1. The main purpose of the paper is to obtain information (bounds, in some cases explicit values) concerning the function M(n) (cf. Theorem 1). We also show that Δ(n) is replete (i.e., has a subgroup of index m for every integer m ≥ 1) if, and only if, n is divisible by 20 or by 30 (see Theorem 2).
STOTHERS, W. WILSON. SUBGROUPS OF FINITE INDEX IN (2, 3, n)-TRIANGLE GROUPS. Glasgow mathematical journal, Tome 54 (2012) no. 3, pp. 693-714. doi: 10.1017/S0017089512000298
@article{10_1017_S0017089512000298,
author = {STOTHERS, W. WILSON},
title = {SUBGROUPS {OF} {FINITE} {INDEX} {IN} (2, 3, {n)-TRIANGLE} {GROUPS}},
journal = {Glasgow mathematical journal},
pages = {693--714},
year = {2012},
volume = {54},
number = {3},
doi = {10.1017/S0017089512000298},
url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089512000298/}
}
TY - JOUR AU - STOTHERS, W. WILSON TI - SUBGROUPS OF FINITE INDEX IN (2, 3, n)-TRIANGLE GROUPS JO - Glasgow mathematical journal PY - 2012 SP - 693 EP - 714 VL - 54 IS - 3 UR - http://geodesic.mathdoc.fr/articles/10.1017/S0017089512000298/ DO - 10.1017/S0017089512000298 ID - 10_1017_S0017089512000298 ER -
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