When does an orthomorphism of the cyclic group exist? Prove that orthomorphisms of <mi

skylsn

skylsn

Answered question

2022-06-24

When does an orthomorphism of the cyclic group exist?
Prove that orthomorphisms of Z n exist if and only if n is odd.
An orthomorphism of the cyclic group Z n is a permutation σ : Z n Z n such that i σ ( i ) i is also a permutation.
Actually, one direction is easy: σ ( i ) = 2 i is an orthomorphism of Z n when n is odd. So what's left is to prove the non-existence of orthomorphisms of Z n when n is even.

Answer & Explanation

Layla Love

Layla Love

Beginner2022-06-25Added 29 answers

Suppose you are talking about the additive group Z n (i.e. the numbers modulo n).
If n is even then i = 1 n i 0 mod n. So if σ ( i ) i were a permutation we would have that i = 1 n ( σ ( i ) i ) 0 mod n, but it is 0 as σ ( i ) is a permutation too.

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?