An eight-point obstruction to universality of RBM(4,3)

Unrefereed candidate, Anonymous, version 0.2.0-candidate. A finite integer certificate and written analytic argument establish a necessary leakage inequality on the full classical real binary RBM(4,3) visible closure, an eight-point obstruction to universality, a strictly positive excluded law, and non-sharp total-variation lower bounds. A contrasting exact construction represents every distribution on the specified parity-plus-one support. At least four hidden units are necessary; four-hidden sufficiency, smallest excluded support, complete classification, practical training penalties and historical priority are not established.

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