%T A Unifying Theory of True Concurrency Based on CSP and Lazy Observation
%A  Marc L. Smith
%E  Jan F. Broenink,  Herman Roebbers,  Johan P. E. Sunter, Peter H. Welch,  David C. Wood
%B Communicating Process Architectures 2005
%X What if the CSP observer were lazy? This paper considers the
   consequences of altering the behavior of the CSP observer.
   Specifically, what implications would this new behavior have
   on CSP&\[sh]8217;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\-interleaved trace
   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 context of the
   Unifying Theories of Programming, a model of true
   concurrency&\[sh]8212; VCR &\[sh]8212; becomes possible by
   permitting (even encouraging) the CSP observer to be lazy.