Composition of q-entropies and hyperbolic orthogonality

We point out that the q-entropy composition for independent events has exactly the same form as the Pythagorean theorem in hyperbolic geometry. We justify the formal relation of hyperbolic geometry with the q-entropy through the use of the κ-entropy, which is directly related to the hyperboloid model of hyperbolic space. We comment on the relation between orthogonality in this form of the Pythagorean theorem and the independence of the probability distributions appearing in the q-entropy composition through the use of the Dvoretzky-Rogers lemma.