The Linear Time - Branching Time Spectrum I.**This is an extension of [20]. The research reported in this paper has been initiated at CWI in Amsterdam, continued at the Technical University of Munich, and finalized at Stanford University. It has been supported by Sonderforschungsbereich 342 of the TU München and by ONR under grant number N00014-92-J-1974. Part of it was carried out in the preparation of a course Comparative Concurrency Semantics, given at the University of Amsterdam, Spring 1988. A coloured version of this paper is available at http://boole.stanford.edu/pub/spectruml.ps.gz. The Semantics of Concrete, Sequential Processes 论文