2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93876The higher than classical efficiency exhibited by some quantum algorithms is here ascribed to their non-mechanistic character, which becomes evident by joining the notions of entanglement and quantum measurement. Measurement analogically sets a (partial) constraint on the output of the computation of a hard-to-reverse function. This constraint goes back in time along the reversible computation process, computing the reverse function, which yields quantum efficiency. The evolution, comprising wave function collapse (here a revamped notion), is non-mechanistic as it is driven by both an initial condition and a final constraint. It seems that the more the output is constrained by measurement, the higher can be the efficiency. Setting a complete constraint, by means of a special Zeno effect, yields (speculatively) NP-complete=P.revision 4: further developed the notion that quantum efficiency comes from driving the computation process through a final condition; various clarifications after receiving comments; reduced the number of figures; 10 text pages (1 file), 2 figures (1 additional file); submitted for the Proceedings of the International Quantum Structures Association Conference, Liptovsky Jan, September 1998Quantum Physicstext