Groups and Inner Automorphisms

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In summary, in this conversation, the problem of showing that G/Z(G) \cong Inn(G) is being discussed. The attempt at a solution involves finding a surjective homomorphism and applying the first isomorphism theorem. However, the attempt provided does not seem to be correct. Instead, the problem can be solved by identifying an element g of G with an inner automorphism of G and showing that different elements g1 and g2 can define the same automorphism.
  • #1
Locoism
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Homework Statement


Let G be a group. Show that G/Z(G) [itex]\cong[/itex] Inn(G)


The Attempt at a Solution


G/Z(G) = gnZ(G) for some g ε G and for any n ε N
choose some g-1 such that
g(g-1h) = g(hg-1)
and the same can be done switching the g and g-1

This doesn't feel right at all...
 
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  • #2
Locoism said:

The Attempt at a Solution


G/Z(G) = gnZ(G) for some g ε G and for any n ε N
choose some g-1 such that
g(g-1h) = g(hg-1)
and the same can be done switching the g and g-1

This doesn't feel right at all...

I don't see what this has to do with the problem??

Can you find a surjective homomorphism

[tex]f:G\rightarrow Inn(G)[/tex]

and then apply the first isomorphism theorem?
 
  • #3
Locoism said:

Homework Statement


Let G be a group. Show that G/Z(G) [itex]\cong[/itex] Inn(G)


The Attempt at a Solution


G/Z(G) = gnZ(G) for some g ε G and for any n ε N
choose some g-1 such that
g(g-1h) = g(hg-1)
and the same can be done switching the g and g-1

This doesn't feel right at all...

No, not right. Given an element g of G can you name an inner automorphism of G corresponding to g? When do two different elements of G, g1 and g2 give define the same automorphism?
 

1. What is a group?

A group is a mathematical structure that consists of a set of elements and a binary operation that combines any two elements in the set to produce a third element. Groups are important in many areas of mathematics, including algebra, geometry, and physics.

2. What is an inner automorphism?

An inner automorphism is a type of automorphism, which is a bijective mapping from a mathematical structure to itself. In the context of groups, an inner automorphism is a mapping that takes an element in the group and maps it to another element in the group by conjugation. In simpler terms, it is a transformation of a group that preserves its structure and operations.

3. How are groups and inner automorphisms related?

Groups and inner automorphisms are closely related because inner automorphisms form a subgroup of the larger group. This subgroup is known as the inner automorphism group, and it consists of all the automorphisms that can be obtained by conjugating elements of the group. In other words, the inner automorphism group is a subgroup of the group that preserves its structure.

4. What is the importance of studying groups and inner automorphisms?

Groups and inner automorphisms are essential tools in mathematics and have many practical applications. In algebra, they are used to study symmetry and properties of equations. In geometry, they are used to understand the structure of shapes and objects. In physics, they are used to describe the symmetries and transformations of physical systems.

5. Can you give an example of a group and its inner automorphism group?

One example of a group and its inner automorphism group is the group of rotations of a regular hexagon. The group consists of six elements, which are the different ways the hexagon can be rotated. The inner automorphism group consists of three elements, which are the rotations by 120, 240, and 360 degrees. These rotations preserve the structure of the hexagon and can be obtained by conjugating elements of the group.

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