Re: Semigroup problem

On May 11, 6:23 pm, José Carlos Santos <jcsan...@xxxxxxxx> wrote:
On 11-05-2008 15:41, marc...@xxxxxxxxx wrote:

Let * be a semigroup operation that satisfies the following
properties:

all z exists x exists y (x * y = z).
all x all y (F(x) * G(y) = y * x).

The problem is: prove that * is commutative or find a counterexample
(finite if it is possible) to this claim.

What are F and G?

Capital letters from the English alphabet.

Marc
.

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