Ports, instruments, and conservative predecessors

Quantum channels, instruments, and their finite-dimensional norms use the usual conventions Watrous. Classical stochastic maps are included as channels on commutative algebras.

For an elementary operation, a conservative predecessor graph connects each input port to every output port. A finer predecessor declaration is valid only if the corresponding factorization or no-influence property of the operation has been justified.

A declared temporal order and a dependency graph are different objects. Two events may be ordered by the experimental clock without a system or control wire running from the earlier event to the later one.