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Coxeter group
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===Properties=== Some properties of the finite irreducible Coxeter groups are given in the following table. The order of a reducible group can be computed by the product of its irreducible subgroup orders. {{sort-under}} {| class="wikitable sortable sort-under" ! {{verth|Rank ''n''}} || {{verth|Group<br />symbol}} || {{verth|Alternate<br />symbol}} || [[Coxeter notation|Bracket<br />notation]]||Coxeter<br />graph || data-sort-type="number"|Reflections<br />{{math|1=''m'' = {{sfrac|1|2}}''nh''}}<ref>{{cite book|title=Regular Polytopes|last=Coxeter|first=H. S. M.|chapter=12.6. The number of reflections|date=January 1973 |publisher=Courier Corporation |language=en|isbn=0-486-61480-8}}</ref>||data-sort-type="number"|[[Coxeter element|Coxeter number]]<br />''h''||data-sort-type="number"| [[Order (group theory)|Order]] || Group structure<ref name="wilson">{{Citation|last1=Wilson|first1=Robert A.|author-link=Robert Arnott Wilson|title=The finite simple groups|publisher=[[Springer-Verlag]]|location=Berlin, New York|series=[[Graduate Texts in Mathematics]] 251|isbn=978-1-84800-987-5|doi=10.1007/978-1-84800-988-2|year=2009|chapter=Chapter 2|volume=251}}</ref> || Related [[Uniform polytope|polytopes]] |- align=center !1 ||''A''<sub>1</sub> | ''A''<sub>1</sub> || [ ]|| {{CDD|node}} || 1 ||2 || 2 || <math>S_2</math> || { } |- align=center !2 ||''A''<sub>2</sub> | ''A''<sub>2</sub> || [3]|| {{CDD|node|3|node}} || 3 ||3 || 6 || <math>S_3\cong D_6\cong \operatorname{GO}^-_2(2)\cong \operatorname{GO}^+_2(4)</math> || [[equilateral triangle|{3}]] |- align=center !3 ||''A''<sub>3</sub> | ''A''<sub>3</sub> || [3,3]|| {{CDD|node|3|node|3|node}} || 6 ||4 || 24 || <math>S_4</math> || [[regular tetrahedron|{3,3}]] |- align=center !4 ||''A''<sub>4</sub> | ''A''<sub>4</sub> || [3,3,3]|| {{CDD|node|3|node|3|node|3|node}} || 10 ||5 || 120 || <math>S_5</math> || [[5-cell|{3,3,3}]] |- align=center !5 ||''A''<sub>5</sub> | ''A''<sub>5</sub> || [3,3,3,3]|| {{CDD|node|3|node|3|node|3|node|3|node}} || 15 ||6 || 720 || <math>S_6</math> || [[5-simplex|{3,3,3,3}]] |- align=center !''n'' ||''A''<sub>''n''</sub> || ''A''<sub>''n''</sub> || [3<sup>''n''β1</sup>]|| {{CDD|node|3|node|3}}...{{CDD|3|node|3|node}} || ''n''(''n'' + 1)/2 ||''n'' + 1 || (''n'' + 1)! || <math>S_{n+1}</math> || [[simplex|''n''-simplex]] |- align=center !2 ||''B''<sub>2</sub> | ''C''<sub>2</sub> || [4]|| {{CDD|node|4|node}} || 4 ||4 || 8 || <math>C_{2}\wr S_{2} \cong D_8\cong \operatorname{GO}^-_2(3)\cong \operatorname{GO}^+_2(5)</math> || [[square|{4}]] |- align=center !3 ||''B''<sub>3</sub> | ''C''<sub>3</sub> || [4,3]|| {{CDD|node|4|node|3|node}}|| 9 ||6 || 48 || <math>C_{2}\wr S_{3}\cong S_4\times 2</math> || [[cube|{4,3}]] / [[regular octahedron|{3,4}]] |- align=center !4 ||''B''<sub>4</sub> | ''C''<sub>4</sub> || [4,3,3]|| {{CDD|node|4|node|3|node|3|node}}|| 16 ||8 || 384 || <math>C_{2}\wr S_{4}</math> || [[tesseract|{4,3,3}]] / [[16-cell|{3,3,4}]] |- align=center !5 ||''B''<sub>5</sub> | ''C''<sub>5</sub> || [4,3,3,3]|| {{CDD|node|4|node|3|node|3|node|3|node}} || 25 || 10 || 3840 || <math>C_{2}\wr S_{5}</math> || [[5-cube|{4,3,3,3}]] / [[5-orthoplex|{3,3,3,4}]] |- align=center !''n'' ||''B''<sub>''n''</sub>|| ''C''<sub>''n''</sub> || [4,3<sup>''n''β2</sup>]|| {{CDD|node|4|node|3}}...{{CDD|3|node|3|node}}|| ''n''<sup>2</sup> ||2''n'' || 2<sup>''n''</sup> ''n''! || <math>C_{2}\wr S_{n}</math> || ''n''-cube / [[orthoplex|''n''-orthoplex]] |- align=center !4 ||''D''<sub>4</sub> | ''B''<sub>4</sub> || [3<sup>1,1,1</sup>]|| {{CDD|nodes|split2|node|3|node}}|| 12 ||6 || 192 || <math>C_{2}^3 S_{4}\cong 2^{1+4}\colon S_3</math> || [[16-cell|h{4,3,3}]] / [[16-cell|{3,3<sup>1,1</sup>}]] |- align=center !5 ||''D''<sub>5</sub> | ''B''<sub>5</sub> || [3<sup>2,1,1</sup>]|| {{CDD|nodes|split2|node|3|node|3|node}} || 20 ||8 || 1920 || <math>C_{2}^4 S_{5}</math>|| [[5-demicube|h{4,3,3,3}]] / [[5-orthoplex|{3,3,3<sup>1,1</sup>}]] |- align=center !''n'' ||''D''<sub>''n''</sub> || ''B''<sub>''n''</sub> || [3<sup>''n''β3,1,1</sup>]|| {{CDD|nodes|split2|node|3}}...{{CDD|3|node|3|node}}|| ''n''(''n'' β 1) ||2(''n'' β 1) || 2<sup>''n''−1</sup> ''n''! || <math>C_{2}^{n-1} S_{n}</math> || [[demihypercube|''n''-demicube]] / ''n''-orthoplex |- align=center !6 ||[[E6 (mathematics)|''E''<sub>6</sub>]] |''E''<sub>6</sub> || [3<sup>2,2,1</sup>]|| {{CDD|nodea|3a|nodea|3a|branch|3a|nodea|3a|nodea}} || 36 ||12 || 51840 | <math>\operatorname{GO}_6^{-}(2) \cong \operatorname{SO}_5(3) \cong \operatorname{PSp}_4(3) \colon 2 \cong \operatorname{PSU}_4(2) \colon 2</math> | [[2 21 polytope|2<sub>21</sub>]], [[1 22 polytope|1<sub>22</sub>]] |- align=center !7 ||[[E7 (mathematics)|''E''<sub>7</sub>]] |''E''<sub>7</sub> || [3<sup>3,2,1</sup>]|| {{CDD|nodea|3a|nodea|3a|branch|3a|nodea|3a|nodea|3a|nodea}}|| 63 ||18 || 2903040 || <math> \operatorname{GO}_7(2)\times 2 \cong \operatorname{Sp}_6(2)\times 2 </math>|| [[3 21 polytope|3<sub>21</sub>]], [[2 31 polytope|2<sub>31</sub>]], [[1 32 polytope|1<sub>32</sub>]] |- align=center !8 ||[[E8 (mathematics)|''E''<sub>8</sub>]] | ''E''<sub>8</sub> || [3<sup>4,2,1</sup>]|| {{CDD|nodea|3a|nodea|3a|branch|3a|nodea|3a|nodea|3a|nodea|3a|nodea}}|| 120 ||30 || 696729600 || <math>2\cdot\operatorname{GO}_8^{+}(2)</math>||[[4 21 polytope|4<sub>21</sub>]], [[2 41 polytope|2<sub>41</sub>]], [[1 42 polytope|1<sub>42</sub>]] |- align=center !4 ||[[F4 (mathematics)|''F''<sub>4</sub>]] |''F''<sub>4</sub> || [3,4,3]|| {{CDD|node|3|node|4|node|3|node}} || 24 ||12 || 1152 ||<math>\operatorname{GO}^+_4(3)\cong 2^{1+4}\colon(S_3 \times S_3)</math>|| [[24-cell|{3,4,3}]] |- align=center !2 ||[[G2 (mathematics)|''G''<sub>2</sub>]] || β (''D''{{supsub|6|2}}) || [6]|| {{CDD|node|6|node}} || 6 ||6 || 12 || <math>D_{12}\cong \operatorname{GO}^-_2(5)\cong \operatorname{GO}^+_2(7)</math>|| [[hexagon|{6}]] |- align=center !2 ||''I''<sub>2</sub>(5) || ''G''<sub>2</sub> || [5]||{{CDD|node|5|node}} || 5 || 5 || 10 || <math>D_{10}\cong \operatorname{GO}^-_2(4)</math>|| [[pentagon|{5}]] |- align=center !3 ||''H''<sub>3</sub> | ''G''<sub>3</sub> || [3,5]|| {{CDD|node|5|node|3|node}} || 15 ||10 || 120 || <math>2\times A_5</math>|| [[icosahedron|{3,5}]] / [[dodecahedron|{5,3}]] |- align=center !4 ||''H''<sub>4</sub> | ''G''<sub>4</sub> || [3,3,5]|| {{CDD|node|5|node|3|node|3|node}} || 60 ||30 || 14400 || <math>2\cdot(A_5\times A_5)\colon 2</math>{{efn|an index 2 subgroup of <math>\operatorname{GO}^+_4(5)</math>}}|| [[120-cell|{5,3,3}]] / [[600-cell|{3,3,5}]] |- align=center !2 ||''I''<sub>2</sub>(''n'') || ''D''{{supsub|''n''|2}}|| [''n'']|| {{CDD|node|n|node}} || ''n'' ||''n'' || 2''n'' | <math>D_{2n}</math> <math>\cong \operatorname{GO}^-_2(n-1)</math> when ''n'' = ''p''<sup>''k''</sup> + 1, ''p'' prime <math>\cong \operatorname{GO}^+_2(n+1)</math> when ''n'' = ''p''<sup>''k''</sup> β 1, ''p'' prime | [[regular polygon|{''p''}]] |}
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