Introduction

  1)Multimedia system integrates different kinds of media items. The temporal interrelation between these items becomes more and more important. Incorrect synchronization of sound and image in a movie will make it terrible or impossible to watch. Some formal specification methods should be provided to describle the temporal relation.

  2)Point-based temporal framework and Interval-based temporal framework are proposed to deal with the theoretical possible temporal relations. 

  3)The elemetary units in point-based temporal model are events which are points in a time space.And given one pair of events, one is before ,simultaneous or after the other.Also it is possible for more than one relation is true because of nondeterminacy.

  4)In interval-based temporal framework, the basic units are interval,which is a time duration. The basic temporal operators between these intervals are before,meet,overlap,finish,during,starts and equals [Thomas94]. Because one interval can be represented by its begining and end, some relation exists between the point-based framework and interval-based framework. The expressiveness of temporal model can be assesed by how many point-based temporal operators or interval-based temporal operators can be expressed.                               

  5) In MSE, the hypergraph is used to represent the tmeporal relations between different parts of multimedia documents.