What if the CSP observerwere lazy? This paperconsidersthe consequences of altering the behavior of the CSP observer. Specifically, what implications would this new behavior have on CSP's traces? Laziness turns out to be a useful metaphor. We show how laziness permits transforming CSP into a model of true concurrency (i.e., non-interleavedtrace semantics). Furthermore, the notion of a lazy observer supports tenets of view-centric reasoning (VCR): parallel events (i.e., true concurrency), multiple observers (i.e., different views), and the possibility of imperfect observation. We know from the study of programming languages that laziness is not necessarily a negative quality; it provides the possibility of greater expression and power in the programswe write. Similarly, within the contextof the UnifyingTheoriesof Programming, a model of true concurrency — VCR — becomes possible by permitting (even encouraging) the CSP observer to be lazy.
IOS Press, Inc.
6751 Tepper Drive
Clifton, VA 20124
Tel.: +1 703 830 6300
Fax: +1 703 830 2300 email@example.com
(Corporate matters and books only) IOS Press c/o Accucoms US, Inc.
For North America Sales and Customer Service
West Point Commons
Lansdale PA 19446
Tel.: +1 866 855 8967
Fax: +1 215 660 5042 firstname.lastname@example.org