***************************************************************************** * www.FindStat.org - The Combinatorial Statistic Finder * * * * Copyright (C) 2019 The FindStatCrew * * * * This information is distributed in the hope that it will be useful, * * but WITHOUT ANY WARRANTY; without even the implied warranty of * * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * ***************************************************************************** ----------------------------------------------------------------------------- Statistic identifier: St001789 ----------------------------------------------------------------------------- Collection: Finite Cartan types ----------------------------------------------------------------------------- Description: The number of types of reflection subgroups of the associated Weyl group. Let $\mathcal{R} \subseteq W$ be the set of reflections in the Weyl group $W$. A (possibly empty) subset $X \subseteq \mathcal{R}$ generates a subgroup of $W$ that is again a reflection group of some (not necessarily reduced) finite type. This is the number of all pairwise different types of subgroups of $W$ obtained this way (including type $A_0$). ----------------------------------------------------------------------------- References: ----------------------------------------------------------------------------- Code: ----------------------------------------------------------------------------- Statistic values: ['A',1] => 2 ['A',2] => 3 ['B',2] => 4 ['G',2] => 5 ['A',3] => 5 ['B',3] => 9 ['C',3] => 9 ['A',4] => 7 ['B',4] => 17 ['C',4] => 17 ['D',4] => 8 ['F',4] => 19 ['A',5] => 11 ['B',5] => 31 ['C',5] => 31 ['D',5] => 14 ['A',6] => 15 ['B',6] => 57 ['C',6] => 57 ['D',6] => 23 ['E',6] => 21 ['A',7] => 22 ['B',7] => 98 ['C',7] => 98 ['D',7] => 35 ['E',7] => 41 ['A',8] => 30 ['B',8] => 166 ['C',8] => 166 ['D',8] => 56 ['E',8] => 72 ['C',2] => 4 ----------------------------------------------------------------------------- Created: May 03, 2022 at 14:44 by Dennis Jahn ----------------------------------------------------------------------------- Last Updated: May 04, 2022 at 11:29 by Dennis Jahn