An instance is a machine instance of the NP core: a finite structure describing a Turing machine, by its transitions and their attributes, together with its input and a linear order of positions that bounds both the tape and the number of steps. The machine is deterministic when it has at most one start state, at most one transition applicable in a given state on a given symbol, and each transition has at most one destination state and one written symbol. The instance is a yes-instance of deterministic machine acceptance when it is well-formed, deterministic, and the machine accepts its input within the bounds; the problem is the decision problem of the structures isomorphic to such an instance. Determinism is part of the problem, not a promise.