TIME, QUANTUM-MECHANICS, AND DECOHERENCE

State-reduction and the notion of ''actuality'' are compared to ''pass age'' through time and the notion of ''the present''; already in class ical relativity the latter give rise to difficulties. The solution pro posed here is to treat both tense and value-definiteness as relational properties or ''facts as relations''; likewise the notions of change and probability. In both cases ''essential'' characteristics are absen t: temporal relations are tenselessly true; probabilistic relations ar e deterministically true. The basic ideas go back to Everett, although the technical development makes use of the decoherent histories theor y of Griffiths, Omnes, and Gell-Mann and Hartle. Alternative interpret ations of the decoherent histories framework are also considered.