| | Group Theory at the Library of Math (Free Online Mathematics) (Site not responding. Last check: 2007-10-20) |
 | | In this topic, many examples are given to explain the importance of permutation groups when the underlying set is a finite set of counting numbers; and the matrix form and cycle notation of such permutations are detailed so as to fully explore the groups of permutations of finite sets of counting numbers (called symmetric groups). |
 | | Basically, the center of a group is the collection of elements in the group that commute with all elements in the group and the centralizer of a given element in the group is the collection of all elements in the group that commute with that given element. |
 | | Finally, homomorphisms, kernels, normal subgroups, and quotient groups are defined; and lastly, using a quotient group, it is shown that normal subgroups are kernels of homomorphisms. |
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