 A generalisation of Deutsch’s problem, called the Deutsch-Jozsa problem (Deutsch and Jozsa 1992), enlarges the class of functions under consideration so as to include all of the functions \(f:\{0,1\}^n\to\{0,1\}\), i.e. rather than only considering \(n = 1\). The best deterministic classical algorithm for determining whether a given such function is constant or balanced requires \(\frac{2^{n}}{2}+1\) queries to an oracle in order to solve this problem. In a quantum computer, however, we can answer the question using one oracle call. Generalising our conclusion regarding the Deutsch algorithm, we may say that the Deutsch-Jozsa algorithm allows one to evaluate a global property of the function in one measurement because the output state is a superposition of balanced and constant states such that the balanced states all lie in a subspace orthogonal to the constant states and can therefore be distinguished from the latter in a single measurement (Bub 2006a)