Need Help in Direct Product and Quotient (factor) Group

In summary, the conversation discusses various questions and attempts related to abstract algebra. The first question asks about the relationship between direct products of Z3 and Z7 and whether Z4 x Z2 is equal to Z8. The second question asks for clarification on the elements in Z2 x Z4 and whether it is a Cartesian product. The third question discusses the quotient/factor group Z/nZ and how to find its elements, using the example of Z/5Z = Z5. The speaker requests further explanations for clarification.
  • #1
Kenji Liew
25
0
Hi All. I have several questions on abstract algebra.

Here are my questions and the attempts I had done so far.

(1)Let denote Z as the integer.According to theorem, the direct product of Z3 X Z7 = Z21.
Hence, is Z4 X Z2 is equal to Z8?
Z2X Z2 is equal to Z4?

(2)For Z4 ={0,1,2,3 }, and Z2 ={0,1}.
Then what are the elements will be for Z2 x Z4? Is this a Cartesian product?

(3) We know Z/nZ =Zn, it's a quotient/factor group where nz can be defined as (aH)(bH) = (ab)H. To have a numerical example, we have Z/5Z= Z5.
As usual Z5= {0,1,2,3,4}. But what is the elements contain in Z/5Z and how to find the elements so that the Z/5Z= Z5?

I need some explanations to make me clearer. Thanks a lot ;)
 
Last edited:
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  • #2
(3) Just consider addition in Z modulo 5.
 

1. What is a direct product group?

A direct product group is a mathematical concept that combines two or more groups to form a new group. It is denoted by the symbol "x" and represents the Cartesian product of the individual groups. This means that the elements of the direct product group are ordered pairs of elements from the original groups.

2. What is the purpose of a direct product group?

The purpose of a direct product group is to combine the structures and properties of two or more groups to form a new group. This allows for a more comprehensive understanding of the original groups and can be used to solve more complex mathematical problems.

3. How do you find the order of a direct product group?

The order of a direct product group is equal to the product of the orders of the individual groups. For example, if Group A has an order of 4 and Group B has an order of 3, the direct product group (AxB) will have an order of 12.

4. What is a quotient (factor) group?

A quotient (factor) group is a mathematical concept that results from dividing a group by one of its normal subgroups. It is denoted by the symbol "G/N" where G is the original group and N is the normal subgroup. The elements of the quotient group are the cosets of N in G.

5. How do you determine the order of a quotient group?

The order of a quotient group is equal to the index of the normal subgroup in the original group. This can be calculated by dividing the order of the original group by the order of the normal subgroup. For example, if Group G has an order of 12 and N is a normal subgroup with an order of 3, the quotient group (G/N) will have an order of 4.

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