We explore an identity between two branching graphs and propose a physical
meaning in the context of the gauge-gravity correspondence. From the
mathematical point of view, the identity equates probabilities associated with
GT, the branching graph of the unitary groups, with probabilities
associated with Y, the branching graph of the symmetric groups. In
order to furnish the identity with physical meaning, we exactly reproduce these
probabilities as the square of three point functions involving certain
hook-shaped backgrounds. We study these backgrounds in the context of LLM
geometries and discover that they are domain walls interpolating two AdS spaces
with different radii. We also find that, in certain cases, the probabilities
match the eigenvalues of some observables, the embedding chain charges. We
finally discuss a holographic interpretation of the mathematical identity
through our results.Comment: 34 pages. version published in journa