Remark: Reversible recycling

A specified complete unitary may be uncomputed when its required registers remain available. This is reversible recycling of a coherent computation, not deletion of its unknown input.

A local operation on $B$, with all outputs ignored, cannot improve the pre-existing channel $\mathcal{N}$. Exact recovery from $R$ requires a constant complete complement. A fixed mixed complement gives the syndrome form (eq:normalform); it does not assert that every physical work register has already been reset to a pure blank state.

These channel facts are compatible with irreversible erasure costs. They establish neither those costs nor a holographic encoding.