Search results
Results From The WOW.Com Content Network
The symmetric group on a finite set is the group whose elements are all bijective functions from to and whose group operation is that of function composition. [1] For finite sets, "permutations" and "bijective functions" refer to the same operation, namely rearrangement. The symmetric group of degree is the symmetric group on the set .
The symmetry group of a snowflake is D 6, a dihedral symmetry, the same as for a regular hexagon. In mathematics, a dihedral group is the group of symmetries of a regular polygon, [1][2] which includes rotations and reflections. Dihedral groups are among the simplest examples of finite groups, and they play an important role in group theory and ...
The symmetric group of degree n ≥ 4 has Schur covers of order 2⋅n! There are two isomorphism classes if n ≠ 6 and one isomorphism class if n = 6. The alternating group of degree n has one isomorphism class of Schur cover, which has order n! except when n is 6 or 7, in which case the Schur cover has order 3⋅n!.
For n = 3, 4 there are two additional one-dimensional irreducible representations, corresponding to maps to the cyclic group of order 3: A 3 ≅ C 3 and A 4 → A 4 /V ≅ C 3. For n ≥ 7, there is just one irreducible representation of degree n − 1, and this is the smallest degree of a non-trivial irreducible representation.
For n > 4, the symmetric group of degree n has only the alternating group as a nontrivial normal subgroup (see Symmetric group § Normal subgroups). For n > 4 , the alternating group A n {\displaystyle {\mathcal {A}}_{n}} is simple (that is, it does not have any nontrivial normal subgroup) and not abelian .
A 4 is isomorphic to PSL 2 (3) [1] and the symmetry group of chiral tetrahedral symmetry. A 5 is isomorphic to PSL 2 (4), PSL 2 (5), and the symmetry group of chiral icosahedral symmetry. (See [1] for an indirect isomorphism of PSL 2 (F 5) → A 5 using a classification of simple groups of order 60, and here for a direct proof). A 6 is ...
The group of isometries of space induces a group action on objects in it, and the symmetry group Sym (X) consists of those isometries which map X to itself (as well as mapping any further pattern to itself). We say X is invariant under such a mapping, and the mapping is a symmetry of X. The above is sometimes called the full symmetry group of X ...
V is the symmetry group of this cross: flipping it horizontally (a) or vertically (b) or both (ab) leaves it unchanged.A quarter-turn changes it. In two dimensions, the Klein four-group is the symmetry group of a rhombus and of rectangles that are not squares, the four elements being the identity, the vertical reflection, the horizontal reflection, and a 180° rotation.