# Groups of order 100

## Contents

See pages on algebraic structures of order 100| See pages on groups of a particular order

## Statistics at a glance

The number 100 has 2 and 5 as its only prime factors. The prime factorization is as follows: $\! 100 = 2^2 \cdot 5^2 = 4 \cdot 25$

There are only two prime factors of this number. Order has only two prime factors implies solvable (by Burnside's $p^aq^b$-theorem) and hence all groups of this order are solvable groups (specifically, finite solvable groups). Another way of putting this is that the order is a solvability-forcing number. In particular, there is no simple non-abelian group of this order.

Quantity Value Explanation
Total number of groups up to isomorphism 16
Number of abelian groups up to isomorphism 4 (number of abelian groups of order $2^2$) $\times$(number of abelian groups of order $5^2$) = (number of unordered integer partitions of 2) $\times$ (number of unordered integer partitions of 2) = $2 \times 2 = 4$.
See classification of finite abelian groups and structure theorem for finitely generated abelian groups.
Number of nilpotent groups up to isomorphism 4 (number of groups of order 4) $\times$ (number of groups of order 25) = $2 \times 2 = 4$.
See number of nilpotent groups equals product of number of groups of order each maximal prime power divisor, which in turn follows from equivalence of definitions of finite nilpotent group.
Number of supersolvable groups up to isomorphism 16
Number of solvable groups up to isomorphism 16

## GAP implementation

The order 100 is part of GAP's SmallGroup library. Hence, any group of order 100 can be constructed using the SmallGroup function by specifying its group ID. Also, IdGroup is available, so the group ID of any group of this order can be queried.

Further, the collection of all groups of order 100 can be accessed as a list using GAP's AllSmallGroups function.

Here is GAP's summary information about how it stores groups of this order, accessed using GAP's SmallGroupsInformation function:

gap> SmallGroupsInformation(100);

There are 16 groups of order 100.
They are sorted by their Frattini factors.
1 has Frattini factor [ 10, 1 ].
2 has Frattini factor [ 10, 2 ].
3 has Frattini factor [ 20, 3 ].
4 has Frattini factor [ 20, 4 ].
5 has Frattini factor [ 20, 5 ].
6 has Frattini factor [ 50, 3 ].
7 has Frattini factor [ 50, 4 ].
8 has Frattini factor [ 50, 5 ].
9 - 16 have trivial Frattini subgroup.

For the selection functions the values of the following attributes
are precomputed and stored:
IsAbelian, IsNilpotentGroup, IsSupersolvableGroup, IsSolvableGroup,
LGLength, FrattinifactorSize and FrattinifactorId.

This size belongs to layer 2 of the SmallGroups library.
IdSmallGroup is available for this size.