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In mathematical finite group theory, a rank 3 permutation group acts transitively on a set such that the stabilizer of a point has 3 orbits. The study of these groups was started by Higman (1964, 1971). Several of the sporadic simple groups were discovered as rank 3 permutation groups.
The primitive rank 3 permutation groups are all in one of the following classes:
If G is any 4-transitive group acting on a set S, then its action on pairs of elements of S is a rank 3 permutation group.[1] In particular most of the alternating groups, symmetric groups, and Mathieu groups have 4-transitive actions, and so can be made into rank 3 permutation groups.
The projective general linear group acting on lines in a projective space of dimension at least 3 is a rank-3 permutation group.
Several 3-transposition groups are rank-3 permutation groups (in the action on transpositions).
It is common for the point-stabilizer of a rank-3 permutation group acting on one of the orbits to be a rank-3 permutation group. This gives several "chains" of rank-3 permutation groups, such as the Suzuki chain and the chain ending with the Fischer groups.
Some unusual rank-3 permutation groups (many from (Liebeck & Saxl 1986)) are listed below.
For each row in the table below, in the grid in the column marked "size", the number to the left of the equal sign is the degree of the permutation group for the permutation group mentioned in the row. In the grid, the sum to the right of the equal sign shows the lengths of the three orbits of the stabilizer of a point of the permutation group. For example, the expression 15 = 1+6+8 in the first row of the table under the heading means that the permutation group for the first row has degree 15, and the lengths of three orbits of the stabilizer of a point of the permutation group are 1, 6 and 8 respectively.
Group Point stabilizer size Comments A6 = L2(9) = Sp4(2)' = M10' S4 15 = 1+6+8 Pairs of points, or sets of 3 blocks of 2, in the 6-point permutation representation; two classes A9 L2(8):3 120 = 1+56+63 Projective line P1(8); two classes A10 (A5×A5):4 126 = 1+25+100 Sets of 2 blocks of 5 in the natural 10-point permutation representation L2(8) 7:2 = Dih(7) 36 = 1+14+21 Pairs of points in P1(8) L3(4) A6 56 = 1+10+45 Hyperovals in P2(4); three classes L4(3) PSp4(3):2 117 = 1+36+80 Symplectic polarities of P3(3); two classes G2(2)' = U3(3) PSL3(2) 36 = 1+14+21 Suzuki chain U3(5) A7 50 = 1+7+42 The action on the vertices of the Hoffman-Singleton graph; three classes U4(3) L3(4) 162 = 1+56+105 Two classes Sp6(2) G2(2) = U3(3):2 120 = 1+56+63 The Chevalley group of type G2 acting on the octonion algebra over GF(2) Ω7(3) G2(3) 1080 = 1+351+728 The Chevalley group of type G2 acting on the imaginary octonions of the octonion algebra over GF(3); two classes U6(2) U4(3):22 1408 = 1+567+840 The point stabilizer is the image of the linear representation resulting from "bringing down" the complex representation of Mitchell's group (a complex reflection group) modulo 2; three classes M11 M9:2 = 32:SD16 55 = 1+18+36 Pairs of points in the 11-point permutation representation M12 M10:2 = A6.22 = PΓL(2,9) 66 = 1+20+45 Pairs of points, or pairs of complementary blocks of S(5,6,12), in the 12-point permutation representation; two classes M22 24:A6 77 = 1+16+60 Blocks of S(3,6,22) J2 U3(3) 100 = 1+36+63 Suzuki chain; the action on the vertices of the Hall-Janko graph Higman-Sims group HS M22 100 = 1+22+77 The action on the vertices of the Higman-Sims graph M22 A7 176 = 1+70+105 Two classes M23 M21:2 = L3(4):22 = PΣL(3,4) 253 = 1+42+210 Pairs of points in the 23-point permutation representation M23 24:A7 253 = 1+112+140 Blocks of S(4,7,23) McLaughlin group McL U4(3) 275 = 1+112+162 The action on the vertices of the McLaughlin graph M24 M22:2 276 = 1+44+231 Pairs of points in the 24-point permutation representation G2(3) U3(3):2 351 = 1+126+244 Two classes G2(4) J2 416 = 1+100+315 Suzuki chain M24 M12:2 1288 = 1+495+792 Pairs of complementary dodecads in the 24-point permutation representation Suzuki group Suz G2(4) 1782 = 1+416+1365 Suzuki chain G2(4) U3(4):2 2016 = 1+975+1040 Co2 PSU6(2):2 2300 = 1+891+1408 Rudvalis group Ru 2F4(2) 4060 = 1+1755+2304 Fi22 2.PSU6(2) 3510 = 1+693+2816 3-transpositions Fi22 Ω7(3) 14080 = 1+3159+10920 Two classes Fi23 2.Fi22 31671 = 1+3510+28160 3-transpositions G2(8).3 SU3(8).6 130816 = 1+32319+98496 Fi23 PΩ8+(3).S3 137632 = 1+28431+109200 Fi24' Fi23 306936 = 1+31671+275264 3-transpositionsRetroSearch is an open source project built by @garambo | Open a GitHub Issue
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