Free group:F2: Difference between revisions
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The free group of rank two is a [[SQ-universal group]]. In particular, it has subgroups that are free of every finite rank as well as a free subgroup of countable rank. | The free group of rank two is a [[SQ-universal group]]. In particular, it has subgroups that are free of every finite rank as well as a free subgroup of countable rank. | ||
==Arithmetic functions== | |||
{| class="wikitable" border="1" | |||
! Function !! Value !! Explanation | |||
|- | |||
| [[order of a group|order]] || infinite (countable) || | |||
|- | |||
| [[exponent of a group|exponent]] || infinite (countable) || | |||
|- | |||
| [[Fitting length]] || not defined || There is a nontrivial [[nilpotent normal subgroup]]. | |||
|} | |||
==Group properties== | |||
{| class="wikitable" border="1" | |||
! Property !! Satisfied !! Explanation !! Comment | |||
|- | |||
| [[dissatisfies property::cyclic group]] || No || || | |||
|- | |||
| [[dissatisfies property::abelian group]] || No || || | |||
|- | |||
| [[dissatisfies property::nilpotent group]] || No || || | |||
|- | |||
| [[dissatisfies property::solvable group]] || No || || | |||
|- | |||
| [[satisfies property::free group]] || Yes || || | |||
|- | |||
| [[satisfies property::hypocentral group]] || Yes || || | |||
|- | |||
| [[satisfies property::hypoabelian group]] || Yes || || | |||
|- | |||
| [[satisfies property::imperfect group]] || Yes || || | |||
|} | |||
==GAP implementation== | ==GAP implementation== | ||
Revision as of 00:13, 10 September 2009
This article is about a particular group, i.e., a group unique upto isomorphism. View specific information (such as linear representation theory, subgroup structure) about this group
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Definition
The free group of rank two, also written as , is defined as the free group on a generating set of size two. is the smallest possible rank for a free non-abelian group (the free groups of rank and are respectively the trivial group and the group of integers).
The free group of rank two is a SQ-universal group. In particular, it has subgroups that are free of every finite rank as well as a free subgroup of countable rank.
Arithmetic functions
| Function | Value | Explanation |
|---|---|---|
| order | infinite (countable) | |
| exponent | infinite (countable) | |
| Fitting length | not defined | There is a nontrivial nilpotent normal subgroup. |
Group properties
| Property | Satisfied | Explanation | Comment |
|---|---|---|---|
| cyclic group | No | ||
| abelian group | No | ||
| nilpotent group | No | ||
| solvable group | No | ||
| free group | Yes | ||
| hypocentral group | Yes | ||
| hypoabelian group | Yes | ||
| imperfect group | Yes |
GAP implementation
The free group of rank two can be constructed using GAP with the GAP:FreeGroup command:
FreeGroup(2);
Further, the generators can also be referred to. For instance, if we use:
F := FreeGroup(2);
Then the two generators can be referred to as and .