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Difference between revisions of "Subnormal subgroup"

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''attainable subgroup''
 
''attainable subgroup''
  
Any member of any [[Subnormal series|subnormal series]] of a group. To indicate the subnormality of a subgroup <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909701.png" /> in a group <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909702.png" />, the notation <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909703.png" /> is used.
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Any member of any [[subnormal series]] of a group. To indicate the subnormality of a subgroup $H$ in a group $G$, the notation $H \lhd\!\lhd G$ is used.
  
 
====References====
 
====References====
<table><TR><TD valign="top">[1]</TD> <TD valign="top">  M.I. Kargapolov,  J.I. [Yu.I. Merzlyakov] Merzljakov,  "Fundamentals of the theory of groups" , Springer  (1979)  (Translated from Russian)</TD></TR></table>
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<table>
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<TR><TD valign="top">[1]</TD> <TD valign="top">  M.I. Kargapolov,  J.I. [Yu.I. Merzlyakov] Merzljakov,  "Fundamentals of the theory of groups" , Springer  (1979)  (Translated from Russian)</TD></TR>
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</table>
  
  
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A subnormal subgroup is also called a subinvariant subgroup.
 
A subnormal subgroup is also called a subinvariant subgroup.
  
A subnormal subgroup of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909704.png" /> that coincides with its commutator subgroup and whose quotient by its centre is simple is called a component of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909705.png" />. The product of all components of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909706.png" /> is known as the layer of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909707.png" />. It is an important characteristic subgroup of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/s/s090/s090970/s0909708.png" /> in the theory of finite simple groups, see e.g. [[#References|[a1]]].
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A subnormal subgroup of $G$ that coincides with its commutator subgroup and whose quotient by its centre is simple is called a component of $G$. The product of all components of $G$ is known as the layer of $G$. It is an important [[characteristic subgroup]] of $G$ in the theory of finite simple groups, see e.g. [[#References|[a1]]].
  
 
====References====
 
====References====
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  M. Suzuki,  "Group theory" , '''1–2''' , Springer  (1986)</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  J.C. Lennox,  S.E. Stonehewer,  "Subnormal subgroups of groups" , Clarendon Press  (1987)</TD></TR><TR><TD valign="top">[a3]</TD> <TD valign="top">  D.J.S. Robinson,  "A course in the theory of groups" , Springer  (1982)</TD></TR></table>
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<table>
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<TR><TD valign="top">[a1]</TD> <TD valign="top">  M. Suzuki,  "Group theory" , '''1–2''' , Springer  (1986)</TD></TR>
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<TR><TD valign="top">[a2]</TD> <TD valign="top">  J.C. Lennox,  S.E. Stonehewer,  "Subnormal subgroups of groups" , Clarendon Press  (1987)</TD></TR>
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<TR><TD valign="top">[a3]</TD> <TD valign="top">  D.J.S. Robinson,  "A course in the theory of groups" , Springer  (1982)</TD></TR>
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</table>
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Revision as of 19:37, 28 February 2018

attainable subgroup

Any member of any subnormal series of a group. To indicate the subnormality of a subgroup $H$ in a group $G$, the notation $H \lhd\!\lhd G$ is used.

References

[1] M.I. Kargapolov, J.I. [Yu.I. Merzlyakov] Merzljakov, "Fundamentals of the theory of groups" , Springer (1979) (Translated from Russian)


Comments

A subnormal subgroup is also called a subinvariant subgroup.

A subnormal subgroup of $G$ that coincides with its commutator subgroup and whose quotient by its centre is simple is called a component of $G$. The product of all components of $G$ is known as the layer of $G$. It is an important characteristic subgroup of $G$ in the theory of finite simple groups, see e.g. [a1].

References

[a1] M. Suzuki, "Group theory" , 1–2 , Springer (1986)
[a2] J.C. Lennox, S.E. Stonehewer, "Subnormal subgroups of groups" , Clarendon Press (1987)
[a3] D.J.S. Robinson, "A course in the theory of groups" , Springer (1982)
How to Cite This Entry:
Subnormal subgroup. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Subnormal_subgroup&oldid=42877
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