Simultaneity in Event Structures

Various brand of event structures, prime, bundle, flow, asymmetric, inhibitor just to mention some, have been proposed to face the various kinds of causality and conflict arising in computation. The notion of simultaneity, i.e., the faithful representation that certain events have to occur together, is usually left out from the models for concurrent computations, with some notably exceptions like Pratt's Chu spaces or Bruni&Montanari's Zero-Safe nets. In this paper we propose a notion of event, structures with simultaneity to take into account the simultaneity and we relate the introduced notion with the prime event structures and domains.