Namespaces
Variants
Actions

Difference between revisions of "Shmidt group"

From Encyclopedia of Mathematics
Jump to: navigation, search
m (tex encoded by computer)
(→‎Comments: latexify)
 
Line 25: Line 25:
 
$$  
 
$$  
 
C _ {p  ^ {i}  }  = \  
 
C _ {p  ^ {i}  }  = \  
\mathbf Z / ( p  ^ {i} )  \rightarrow  \mathbf Z / ( p  ^ {i+} 1 )  = \  
+
\mathbf Z / ( p  ^ {i} )  \rightarrow  \mathbf Z / ( p  ^ {i+ 1} )  = \  
C _ {p  ^ {i+} 1 } .
+
C _ {p  ^ {i+  1} } .
 
$$
 
$$
  
Line 40: Line 40:
 
\mathbf Q _ {p} / \mathbf Z _ {p}  $$
 
\mathbf Q _ {p} / \mathbf Z _ {p}  $$
  
(where $ \mathbf Z _ {p} $
+
(where $\mathbf Z_{p} $is the ring of integers of the $p$-adic completion  $  \mathbf Q _ {p} $
is the ring of integers of the $ p $-
 
adic completion  $  \mathbf Q _ {p} $
 
 
of the rational numbers). A group is locally finite if every finite subset generates a finite subgroup. One now has the result that if an infinite locally finite group has only finite subgroups, then it is one of the quasi-cyclic groups  $  C _ {p  ^  \infty  } $.  
 
of the rational numbers). A group is locally finite if every finite subset generates a finite subgroup. One now has the result that if an infinite locally finite group has only finite subgroups, then it is one of the quasi-cyclic groups  $  C _ {p  ^  \infty  } $.  
 
Such a group is also called a Prüfer group.
 
Such a group is also called a Prüfer group.

Latest revision as of 18:45, 11 April 2023


A finite non-nilpotent group all proper subgroups of which are nilpotent (cf. Nilpotent group). A Shmidt group is a solvable group of order $ p ^ \alpha q ^ \beta $, where $ p $ and $ q $ are different prime numbers. In any finite non-nilpotent group there are subgroups that are Shmidt groups. They were introduced by O.Yu. Shmidt in 1924.

References

[1] O.Yu. Shmidt, , Selected works on mathematics , Moscow (1959) pp. 221–227 (In Russian)

Comments

Shmidt's problem (also spelled Smidt's problem) asks which infinite groups are such that every proper subgroup is finite. These groups are sometimes also called Shmidt groups (in the Russian literature). The answer is as follows. Let $ p $ be a prime number. There is a unique imbedding of cyclic groups

$$ C _ {p ^ {i} } = \ \mathbf Z / ( p ^ {i} ) \rightarrow \mathbf Z / ( p ^ {i+ 1} ) = \ C _ {p ^ {i+ 1} } . $$

The direct limit is the quasi-cyclic group

$$ C _ {p ^ \infty } = \ \lim\limits _ {\begin{array}{c} \rightarrow \\ i \end{array} } C _ {p ^ {i} } = \ \mathbf Q _ {p} / \mathbf Z _ {p} $$

(where $\mathbf Z_{p} $is the ring of integers of the $p$-adic completion $ \mathbf Q _ {p} $ of the rational numbers). A group is locally finite if every finite subset generates a finite subgroup. One now has the result that if an infinite locally finite group has only finite subgroups, then it is one of the quasi-cyclic groups $ C _ {p ^ \infty } $. Such a group is also called a Prüfer group.

References

[a1] B.A.F. Wehrfritz, "Locally finite groups" , North-Holland (1973) pp. Chapt. 2, Thm. 2.6
[a2] M.I. Kargapolov, J.I. [Yu.I. Merzlyakov] Merzljakov, "Fundamentals of the theory of groups" , Springer (1979) pp. Chapt. 1, §2 (Translated from Russian)
How to Cite This Entry:
Shmidt group. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Shmidt_group&oldid=48687
This article was adapted from an original article by N.N. Vil'yams (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article