Process matrices and access

This is the specific branch fixed in XXII-C CheungXXIIC (def:process, def:class), using the process-matrix probability framework of OCB. Positivity gives nonnegative probabilities; multilinearity and (eq:validity) give normalization.

The access ${\mathsf{A}}_0$ admits every finite-outcome local qubit instrument, with one use of each process port in a selected experiment. Settings are independent of the process resource. The receiver output used for extraction is its local classical record. Sender and other-party outcomes are summed. No postselection, extra shared ancillary resource, or undeclared interparty feed-forward enters the signalling tests.

Local auxiliaries are permitted only insofar as they implement the declared local maps. There is no spatial position, distance, physical speed, or geometric causal relation in this declaration CheungXXIIC (spec:access).

An identifier $e$ is not time or a refinement scale. There is no joint process on all identifiers and no admitted inter-experiment composition. Unrestricted tensor products of valid processes need not be valid processes; a composition requires its own interface and normalization proof JiaSakharwade.