Symmetric group: Difference between revisions
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===Symbol-free definition=== | ===Symbol-free definition=== | ||
The '''symmetric group''' on a set is the group of all permutations of that set. A group is said to be a symmetric group if it is isomorphic to the symmetric group on some set. | The '''symmetric group''' on a set is the group of all permutations of that set (i.e., bijective maps from the set to itself). A group is said to be a symmetric group if it is isomorphic to the symmetric group on some set. | ||
===Definition with symbols=== | ===Definition with symbols=== | ||
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A group <math>G</math> is termed a '''symmetric group''' if <math>G \cong Sym(S)</math> for some set <math>S</math>. | A group <math>G</math> is termed a '''symmetric group''' if <math>G \cong Sym(S)</math> for some set <math>S</math>. | ||
A bijection between sets gives rise to an isomorphism of the corresponding symmetric groups. Thus, there is only one symmetric group, upto isomorphism, on a set of given cardinality. The symmetric group on a set of cardinality <math>n</math> is denoted <math>Sym(n)</math>, or sometimes <math>S_n</math>. | |||
==Relation with other properties== | ==Relation with other properties== | ||
Revision as of 10:39, 16 June 2008
This article defines a group property: a property that can be evaluated to true/false for any given group, invariant under isomorphism
View a complete list of group properties
VIEW RELATED: Group property implications | Group property non-implications |Group metaproperty satisfactions | Group metaproperty dissatisfactions | Group property satisfactions | Group property dissatisfactions
To get more information on particular symmetric groups, check out Category:Symmetric groups
Definition
Symbol-free definition
The symmetric group on a set is the group of all permutations of that set (i.e., bijective maps from the set to itself). A group is said to be a symmetric group if it is isomorphic to the symmetric group on some set.
Definition with symbols
The symmetric group over a set (denoted as ) is defined as the group of all permutations on , with the multiplication being function composition.
A group is termed a symmetric group if for some set .
A bijection between sets gives rise to an isomorphism of the corresponding symmetric groups. Thus, there is only one symmetric group, upto isomorphism, on a set of given cardinality. The symmetric group on a set of cardinality is denoted , or sometimes .
Relation with other properties
Weaker properties
- Centerless group: All except the symmetric group on two elements are centerless. Further information: Symmetric groups are centerless
- Complete group: All except the symmetric group on two elements and the symmetric group on six elements. Further information: Symmetric groups are complete
Related notions
Alternating group
Finitary symmetric and alternating groups
Subgroups of the symmetric group
IAPS structure
Further information: Permutation IAPS