Is H a Free Commutative Group of Rank n in Z^n?

In summary, a subgroup of finite index is a subset of a larger group that has a finite number of elements and cosets. The index of a subgroup is determined by dividing the order of the larger group by the order of the subgroup. This has important implications in understanding the structure and properties of the group. While a subgroup of finite index can have infinite order, the index can still provide insight into its role within the larger group.
  • #1
charlamov
11
0
show that H is subgroup of finite index in Z^n exactly when H is free comutative group of rank n
 
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  • #2
charlamov said:
show that H is subgroup of finite index in Z^n exactly when H is free comutative group of rank n


What've you done? Do you know the elementary divisors theorem for fin. gen, abelian groups?

DonAntonio
 
  • #3
charlamov said:
show that H is subgroup of finite index in Z^n exactly when H is free comutative group of rank n



THis question doesn't belong at all in science education, but in "Abstract Algebra" in the math department
 

What is a subgroup of finite index?

A subgroup of finite index is a subset of a larger group that contains a finite number of elements and has a finite number of cosets, or distinct left or right translates.

How is the index of a subgroup determined?

The index of a subgroup is determined by dividing the order of the larger group by the order of the subgroup. This gives the number of cosets, or distinct left or right translates, of the subgroup within the larger group.

What is the significance of a subgroup having finite index?

A subgroup of finite index has several important properties, including being normal and having finite cohomological dimension. This makes it a useful tool in studying the structure and properties of a larger group.

Can a subgroup of finite index have infinite order?

Yes, a subgroup of finite index can have infinite order. The index of a subgroup only determines the number of cosets, not the order of the elements within the subgroup.

How does the index of a subgroup affect its role within a larger group?

The index of a subgroup can give insight into the structure and properties of the larger group. A subgroup with a small index may be more influential in the overall behavior of the group, while a subgroup with a larger index may have less impact.

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