Pariah group

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Relationships among the sporadic simple groups. The monster group M is at the top, and the groups which are descended from it are the happy family.
The six which are not connected by an upward path to M (white ellipses) are the pariahs. SporadicGroups.svg
Relationships among the sporadic simple groups. The monster group M is at the top, and the groups which are descended from it are the happy family.
The six which are not connected by an upward path to M (white ellipses) are the pariahs.

In group theory, the term pariah was introduced by Robert Griess in Griess (1982) to refer to the six sporadic simple groups which are not subquotients of the monster group.

The twenty groups which are subquotients, including the monster group itself, he dubbed the happy family.

For example, the orders of J4 and the Lyons Group Ly are divisible by 37. Since 37 does not divide the order of the monster, these cannot be subquotients of it; thus J4 and Ly are pariahs. Three other sporadic groups were also shown to be pariahs by Griess in 1982, and the Janko Group J1 was shown to be the final pariah by Robert A. Wilson in 1986. The complete list is shown below.

List of pariah groups
GroupSizeApprox.
size
Factorized orderFirst
missing
prime
Lyons group, Ly517651790040000005×101628 · 37 · 56 · 7 · 11 · 31 · 37 · 6713
O'Nan group, O'N4608155059205×101129 · 34 · 5 · 73 · 11 · 19 · 3113
Rudvalis group, Ru1459261440001×1011214 · 33 · 53 · 7 · 13 · 2911
Janko group, J4867755710460775628809×1019221 · 33 · 5 · 7 · 113 · 23 · 29 · 31 · 37 · 4313
Janko group, J3502329605×10727 · 35 · 5 · 17 · 197
Janko group, J11755602×10523 · 3 · 5 · 7 · 11 · 1913

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   808,017,424,794,512,875,886,459,904,961,710,757,005,754,368,000,000,000
   = 246 · 320 · 59 · 76 · 112 · 133 · 17 · 19 · 23 · 29 · 31 · 41 · 47 · 59 · 71
   ≈ 8×1053.

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<span class="mw-page-title-main">Sporadic group</span> Finite simple group type not classified as Lie, cyclic or alternating

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<span class="mw-page-title-main">Janko group</span> Index of articles associated with the same name

In the area of modern algebra known as group theory, the Janko groups are the four sporadic simple groups J1, J2, J3 and J4 introduced by Zvonimir Janko. Unlike the Mathieu groups, Conway groups, or Fischer groups, the Janko groups do not form a series, and the relation among the four groups is mainly historical rather than mathematical.

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<span class="mw-page-title-main">Lyons group</span> Sporadic simple group

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In the area of abstract algebra known as group theory, the O'Nan groupO'N or O'Nan–Sims group is a sporadic simple group of order

<span class="mw-page-title-main">Rudvalis group</span> Sporadic simple group

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Pariah may refer to:

Robert Arnott Wilson is a retired mathematician in London, England, who is best known for his work on classifying the maximal subgroups of finite simple groups and for the work in the Monster group. He is also an accomplished violin, viola and piano player, having played as the principal viola in the Sinfonia of Birmingham. Due to a damaged finger, he now principally plays the kora.

<span class="mw-page-title-main">Robert Griess</span> American mathematician

Robert Louis Griess, Jr. is a mathematician working on finite simple groups and vertex algebras. He is currently the John Griggs Thompson Distinguished University Professor of mathematics at University of Michigan.

Janko group J<sub>1</sub> Sporadic simple group

In the area of modern algebra known as group theory, the Janko groupJ1 is a sporadic simple group of order

Janko group J<sub>4</sub> Sporadic simple group

In the area of modern algebra known as group theory, the Janko groupJ4 is a sporadic simple group of order

Janko group J<sub>2</sub> Sporadic simple group

In the area of modern algebra known as group theory, the Janko groupJ2 or the Hall-Janko groupHJ is a sporadic simple group of order

Mathieu group M<sub>24</sub> sporadic simple group

In the area of modern algebra known as group theory, the Mathieu groupM24 is a sporadic simple group of order

<span class="mw-page-title-main">Bernd Fischer (mathematician)</span> German mathematician (1936–2020)

Bernd Fischer was a German mathematician.

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