@InProceedings{Smith05, title = "{A} {U}nifying {T}heory of {T}rue {C}oncurrency {B}ased on {CSP} and {L}azy {O}bservation", author= "Smith, Marc L.", editor= "Broenink, Jan F. and Roebbers, Herman and Sunter, Johan P. E. and Welch, Peter H. and Wood, David C.", pages = "177--188", booktitle= "{C}ommunicating {P}rocess {A}rchitectures 2005", isbn= "978-1-58603-561-7", year= "2005", month= "sep", abstract= "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\&\#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\&\#8212; VCR \&\#8212; becomes possible by permitting (even encouraging) the CSP observer to be lazy." }