 Another issue one may want to model is reasoning about a system from the perspective of an agent that has only partial knowledge about the parts of a system. For a running example, think of a plane controller who has only worked with ACME monitors and knows nothing about electronics. The logic such an agent might use to reason about part \(\mathbf{A}\) of a system (actually part Screens in the case of the controller) will in general consist of some constraints that may not even be global, but satisfied only by some subset of instances (the ACME monitors). The agent’s logic may be incomplete in the sense that it might miss some of the global constraints of the classification (like the ones involving inner components of the monitor). The agent’s logic may also be unsound, in the sense that there might be instances out of the awareness of the agent (say monitors of unfamiliar brands) that falsify some of the agent’s constraints (which do hold of all ACME monitors). A local logic \(L\) in \(\mathbf{A}\) can be “moved” along an infomorphism \(f : \mathbf{A} \rightarrow \mathbf{C}\) in the expected way, that is, its constraints are transformed via \(f^{\wedge}\), while its instances are transformed via \(f^{\vee}\). Natural questions studied in channel theory concerning these notions include the preservation (or not), under translation, of some desirable properties of local logics, such as soundness. 