Showing that groups are isomorphic

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To show that two groups are isomorphic, finding a single isomorphism between them is sufficient. An example discussed is the infinite cyclic group G with generator g, which is isomorphic to Z. The function f(g) = ord(g) is proposed as a bijective homomorphism. It is confirmed that this function is indeed bijective and a homomorphism, though further explanation on these properties is encouraged. Overall, establishing one isomorphism is adequate for proving the isomorphism of two groups.
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If one wants to show that two groups are isomorphic is simply finding a single isomorphism between them sufficient?

For example.

If G is an infinite cyclic group with generator g show that G is isomorphic to Z.

So suppose f(g)=ord(g)

then f is bijective and a homomorphism I believe?
 
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gottfried said:
If one wants to show that two groups are isomorphic is simply finding a single isomorphism between them sufficient?

Yes.

For example.

If G is an infinite cyclic group with generator g show that G is isomorphic to Z.

So suppose f(g)=ord(g)

then f is bijective and a homomorphism I believe?

Yes, this is true. However, you might want to give a bit of explanation on why it is bijective and a homomorphism.
 
Cool thanks for clearing it up.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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