What is the First Isomorphism Theorem?

In summary, the 1st isomorphism theorem states that if there is a homomorphism from group G to group H, then the kernel of the homomorphism is a normal subgroup of G, the image of the homomorphism is a subgroup of H, and the quotient group G/K is isomorphic to the image of the homomorphism. This means that G/K and I have the same structure, or they are essentially the same group.
  • #1
proplaya201
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Homework Statement



can someone explain the 1st isomorphism theorem to me(in simple words) i really don't get it

Homework Equations





The Attempt at a Solution

 
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  • #2
Why don't you write down the 1st isomorphism theorem, so people here will actually know what are you talking about. Not everybody might have learned that theorem adressed with the same name as you!
 
  • #3
If G and H are groups and f is a homomorphism from G to H, then the kernel K of f is a normal subgroup of G, the image of f is a subgroup of H, and the quotient group G /K is isomorphic to the image of f.
 
  • #4
If f: G-> H, then

The kernel, K, of f is a subgroup of G - {x in G such that f(G)= eH}

The Image, I, of f is a subgroup of H- {y in H such that y= f(x) for some x in G}

1) K is a normal subgroup of G.

2) G/K is isomorphic to I.

Do you understand what "homomorphism" and "isomorphism" mean? Do you understand what a "normal subgroup" is and what "G/K" is?
 
  • #5
can you specify G/K is isomorphic to I.
 

Related to What is the First Isomorphism Theorem?

What is the First Isomorphism Theorem?

The First Isomorphism Theorem is a fundamental theorem in abstract algebra that states that given two groups G and H and a homomorphism φ: G → H, there exists a unique group isomorphism Φ: G/ker(φ) → im(φ), where ker(φ) is the kernel of φ and im(φ) is the image of φ.

What is a homomorphism?

A homomorphism is a function between two algebraic structures, such as groups, rings, or fields, that preserves the operations of the structures. In other words, a homomorphism maps elements in one structure to elements in another structure in a way that respects the operations of the structures.

What is the kernel of a homomorphism?

The kernel of a homomorphism φ: G → H is the set of elements in G that are mapped to the identity element in H. In other words, it is the set of elements in G that are "ignored" by the homomorphism.

What is the image of a homomorphism?

The image of a homomorphism φ: G → H is the set of elements in H that are the result of applying the homomorphism to elements in G. In other words, it is the set of elements in H that are "hit" by the homomorphism.

How is the First Isomorphism Theorem useful?

The First Isomorphism Theorem is useful in understanding the structure and relationships between different groups. It allows us to simplify the study of complex groups by breaking them down into smaller, isomorphic groups. It also helps to classify groups and identify important properties and structures within them.

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