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Topic: Normal subgroup


  
  Characteristic subgroup - Wikipedia, the free encyclopedia
In mathematics, a characteristic subgroup of a group G is a subgroup H that is invariant under each automorphism of G.
In this case the subgroup H is invariant under the applications of surjective endomorphisms.
The derived subgroup (or commutator subgroup) of a group is always a fully characteristic subgroup, as is the torsion subgroup of an abelian group.
en.wikipedia.org /wiki/Characteristic_subgroup   (468 words)

  
 Normal subgroup - Wikipedia, the free encyclopedia
In mathematics, a normal subgroup N of a group G is a subgroup invariant under conjugation; that is, for each element n in N and each g in G, the element g
However, a characteristic subgroup of a normal subgroup is normal.
In particular, a normal subgroup of a direct factor is normal.
en.wikipedia.org /wiki/Normal_subgroup   (754 words)

  
 Normal morphism - Wikipedia, the free encyclopedia
In category theory and its applications to mathematics, a normal monomorphism or normal epimorphism is a particularly well-behaved type of morphism.
In that case, we say that a monomorphism is normal if it is the kernel of some morphism, and an epimorphism is normal (or conormal) if it is the cokernel of some morphism.
Suppose that G is a group and H is a subgroup of G.
en.wikipedia.org /wiki/Normal_morphism   (292 words)

  
 Characteristic Subgroups and Normal Structure
However, if G is intransitive or imprimitive, the minimal normal subgroups are found by computing the conjugacy classes of G and looking at the normal subgroups generated by each class.
The normal subgroup lattice of G. The subgroups are found by first determining the minimal normals using the conjugacy classes of G and then extending these layer by layer until G is reached.
Given a group G and a subnormal subgroup H of G, return a sequence of subgroups commencing with G and terminating with H, such that each subgroup is normal in the previous one.
www.math.uiuc.edu /Software/magma/text246.html   (918 words)

  
 Normal and Subnormal Subgroups
The minimal normal subgroups of G. These are obtained by first computing the socle of G and then splitting off the normal factors.
The normal subgroups of G. These are determined by the method of Cannon and Souvignier [CS].
Given a group G, a normal subgroup M of G and a normal subgroup N of G, that is strictly contained in M, the function returns a sequence comprising representatives for the conjugacy classes of complements of M/N in G/N, as subgroups of G. HasComplement(G, M) : GrpPerm, GrpPerm -> BoolElt, GrpPerm
magma.maths.usyd.edu.au /magma/htmlhelp/text279.htm   (2308 words)

  
 [No title]
A finite nilpotent group in which the lattice of normal subgroups is a chain is a cyclic $p$-group.
All examples I found had the property that their normal subgroup lattice was a chain which coincided with its derived series.
Then the normal subgroups of G are its p + 1 maximal subgroups and the terms of the lower central series.
www.bath.ac.uk /~masgcs/problem/commentary10.html   (2226 words)

  
 normal
Normal subgroups of the above groups: 1) The group of all rotational symmetries of the tetrahedron such that each edge get mapped either onto itself or onto the opposing edge (This group of 4 rotations is isomorphic to Z/2 x Z/2 and is a normal subgroup of group 1 above.
Subgroups that aren't normal (aka "abnormal" subgroups): 1) Pick any of the 4 axes of the tetrahedron which pass through a vertex and the center of a face.
N is a normal subgroup iff For every element n of N, there is no element in G which both lies outside of N and which "looks exactly like n does" if you view the polytope from the appropriate angle.
math.ucr.edu /home/baez/normal.html   (2662 words)

  
 A Review of ``Subgroup Lattices of Groups'' by Roland Schmidt
Every normal subgroups is a modular element of the subgroup lattice, and more generally every permutable subgroup (a subgroup M with MH=HM for every subgroup H) is a modular element.
The image of a normal subgroup under a projectivity is not necessarily normal, while, of course, the image of a modular subgroup is modular.
Fortunately it is possible to characterize subgroups of finite index lattice theoretically (and thus the projective image of a subgroup of finite index has finite index).
www.math.hawaii.edu /~ralph/schmidt/sch-protter/sch-protter.html   (1914 words)

  
 Normal subgroups   (Site not responding. Last check: 2007-10-22)
Lots of examples of normal subgroups exist since every subgroup of an abelian group is a normal subgroup.
This is a normal subgroup and although we could prove it by calculation it follows from the following result.
Any subgroup N of index 2 in a group G is a normal subgroup of G.
www.math.csusb.edu /notes/advanced/algebra/gp/node14.html   (114 words)

  
 Normal Structure and Characteristic Subgroups
Otherwise, it is computed as the simultaneous fixed point space of the action of the generators of G on the centre of the Fitting subgroup of G [Eic01].
Returns a normal series of G, the factors of which are either elementary abelian p-groups which are semisimple as GF(p)[G]-modules or free abelian groups which are semisimple as Q[G]-modules.
The series is returned as a sequence of subgroups of G. Note that since polycyclic groups satisfy the ascending chain condition for subgroups, every polycyclic group G has a finite upper central series.
magma.maths.usyd.edu.au /magma/htmlhelp/text452.htm   (829 words)

  
 [No title]
group G and a normal subgroup N of G, the quotient group, or factor group, of G over N is a group that intuitively "collapses" the normal subgroup N to the identity element.
A subgroup N of a group G is normal if and only if the coset equality aN = Na holds for all a in G.
There is a bijective correspondence between the subgroups of G that contain N and the subgroups of G/N; if H is a subgroup of G containing N, then the corresponding subgroup of G/N is π(H).
en-cyclopedia.com /wiki/Factor_group   (692 words)

  
 Cube Lovers: Re: Normal Subgroups of G
It is the minimal normal subgroup of G, such that the factor group G/G' is an abelian group.
Thus the closure and the intersection of N1 and N2 are normal subgroups of GCE (and are therefore subgroups that
Thus there cannot be a normal subgroup of G that is not normal in GCE.
www.math.rwth-aachen.de /~Martin.Schoenert/Cube-Lovers/Martin_Schoenert__Re__Normal_Subgroups_of_G.html   (3004 words)

  
 ABSTRACT ALGEBRA ON LINE: Groups (part 2)
The number of left cosets of H in G is called the index of H in G, and is denoted by [G:H].
G. Definition If N is a normal subgroup of G, then the group of left cosets of N in G is called the factor group of G determined by N. It will be denoted by G/N. Example 3.8.5.
(a) K is a normal subgroup of G. (b) The homomorphism
www.math.niu.edu /~beachy/aaol/groups2.html   (602 words)

  
 [No title]
BH^pfactors ov* *er a quotient of G in a modified sense and this factorisation is an injection.
(1) preker(f) is a subgroup of Sp1 G. (2) ker(f) is a p-toral subgroup of SpG.
X^p as in (S), the kernel ker(f) SpG is not a normal subgroup of G in general.
hopf.math.purdue.edu /Notbohm/kernels.txt   (4000 words)

  
 The Center and a Normal Subgroup Intersect   (Site not responding. Last check: 2007-10-22)
Every normal subgroup intersects the center of g, which is all of g.
Since c commutes with everything, the subgroup d, generated by c and k, is indeed the direct product of c and k.
Since k is normal the conjugate of y lies in k, and the conjugate of xy lies in d, hence d is normal in g.
www.mathreference.com /grp-chain,normint.html   (367 words)

  
 ABSTRACT ALGEBRA: OnLine Study Guide, Section 3.8
If N is a normal subgroup of G, then the set of left cosets of N forms a group under the coset multiplication given by
If N is a normal subgroup of G, then the group of left cosets of N in G is called the factor group of G determined by N. It will be denoted by G/N. Example 3.8.5.
Let G be a group, and let N and H be subgroups of G such that N is normal in G. (a) Prove that HN is a subgroup of G. (b) Prove that N is a normal subgroup of HN.
www.math.niu.edu /~beachy/abstract_algebra/study_guide/38.html   (1057 words)

  
 On Groups Without Large Corefree Subgroups   (Site not responding. Last check: 2007-10-22)
A subgroup H of a group G is corefree if H contains no non-trivial normal subgroup of G, or equivalently the transitive permutation representation of G on the cosets of H is faithful.
We call a subgroup D a ``dedekind'' subgroup of G if all subgroups of D are normal in G.
Examples show that the dedekind subgroups need not have index bounded by a function of k, and the result would not be true with one dedekind subgroup instead of two.
www.math-inst.hu /pub/combinatorics/corefree.html   (126 words)

  
 GAP Manual: 54.8 TestInducedFromNormalSubgroup   (Site not responding. Last check: 2007-10-22)
of the group G is induced from a proper normal subgroup of G.
may also be given as the list of positions of conjugacy classes contained in the normal subgroup in question.
is induced from a proper normal subgroup of the group of
www-groups.dcs.st-and.ac.uk /~gap/Gap3/Manual3/C054S008.htm   (108 words)

  
 [No title]   (Site not responding. Last check: 2007-10-22)
H is a subgroup of G iff H is a sunset of G and H satisfies all the axioms of a group using the multiplication rule of G. Theorems about subgroups: 1.
If H and K are subgroups of G then H intersect K is a subgroup of G. If H is a subgroup of G and N is a normal subgroup of G, then H 2.
intersect N is a normal subgroup of H. If H is a subgroup of G and N is a normal subgroup of G, then NH=HN 3.
www.cs.cmu.edu /People/jcl/classnotes/math/group_theory/subgroup.txt   (117 words)

  
 Joining and Intersecting Subgroups
Using the a/b criterion, the intersection of arbitrarily many subgroups is a subgroup.
Using the x*h/x criterion, the arbitrary intersection of normal subgroups is normal.
Let r be the subgroup generated by k and h, also called k join h, and let j be the intersection of k and h.
www.mathreference.com /grp,join.html   (642 words)

  
 PlanetMath: normal subgroup
More surprisingly, the converse is also true: any normal subgroup
Cross-references: quotient group, projection map, homomorphism, group homomorphism, kernel, conjugacy class, group, subgroup
This is version 6 of normal subgroup, born on 2002-01-05, modified 2002-07-11.
planetmath.org /encyclopedia/NormalSubgroup.html   (77 words)

  
 Chains of Subgroups
Let g be a group, and picture a chain of descending subgroups, each a subgroup of the previous.
Sometimes the phrase "normal series" is used when the distinction between a normal series and a subnormal series is not important.
This is a normal subgroup of index 2.
www.mathreference.com /grp-chain,intro.html   (516 words)

  
 [ref] 72 Monomiality Questions
Monomiality questions usually involve computations in many subgroups and factor groups of a given group, and for these groups often expensive calculations such as that of the character table are necessary.
For example, if you need the normal subgroups of G then they can be computed more efficiently if the character table of G is known, and they can be stored compatibly to the contained G-conjugacy classes.
is not induced from the inertia subgroup of a component of any reducible restriction to a normal subgroup.
www.dma.unina.it /gap4manual/ref/CHAP072.htm   (1754 words)

  
 Math 441 Hw 18
A Group is simple if it has no proper nontrivial normal subgroups.
Show that if a finite group G contains a nontrivial subgroup of index 2 in G, then G is not simple.
Prove: Let H be a normal subgroup of a group G. (a) If G is abelian, then G/H is abelian.
www.andrews.edu /~ohy/math441/Hw18.htm   (62 words)

  
 No Title   (Site not responding. Last check: 2007-10-22)
Let G be a group having a simple subgroup H of index 2.
Let K be another proper normal subgroup of G distinct from H.
Let H be the subgroup of G generated by the chosen Sylow subgroups.
www.math.gatech.edu /~saugata/teaching/fall00/sol3/sol3.html   (736 words)

  
 Some Properties of p-Groups
is not simple because it must have a subgroup of order p and all subgroups must be normal in an abelian group.
maps to a subgroup of the factor group.
Then if H is a normal subgroup of G then H contains a normal subgroup of every divisor p
www-math.cudenver.edu /~rrosterm/simple/node3.html   (231 words)

  
 ABSTRACT ALGEBRA: OnLine Study Guide, §7.4 Solved Problems
Prove that if G is a group of order 56, then G has a normal Sylow 2-subgroup or a normal Sylow 7-subgroup.
Prove that if G is a group of order 105, then G has a normal Sylow 5-subgroup and a normal Sylow 7-subgroup.
Therefore PQ is a subgroup, and it must be normal since its index is the smallest prime divisor of G, so we can apply the result in the previous problem.
www.math.niu.edu /~beachy/abstract_algebra/study_guide/soln74.html   (840 words)

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