Editing X-machine (section)

== 1990s ==
X-machines have received renewed attention since the mid-1990s, when Gilbert Laycock's deterministic [[Stream X-Machine]]<ref name="Lay">Gilbert Laycock (1993) ''The Theory and Practice of Specification Based Software Testing''. PhD Thesis, University of Sheffield. 
  [http://www.mcs.le.ac.uk/people/gtl1/PhDabstract.html Abstract] {{webarchive |url=https://web.archive.org/web/20071105145328/http://www.mcs.le.ac.uk/people/gtl1/PhDabstract.html |date=November 5, 2007 }}</ref> was found to serve as the basis for specifying large software systems that are ''completely'' testable.<ref
  name="HI98">M. Holcombe and F. Ipate (1998)
  ''Correct Systems - Building a Business Process Solution''.
  Springer, Applied Computing Series.</ref>  Another variant,
the [[Communicating X-Machine|Communicating Stream X-Machine]] offers a useful testable model for biological processes<ref name="BeH96">
A. Bell and M. Holcombe (1996) 'Computational models of cellular processing', in ''Computation in Cellular and Molecular Biological Systems'', eds. M. Holcombe, R. Paton and R. Cuthbertson, Singapore, World Scientific Press.</ref> 
and future ''swarm-based'' satellite systems.
<ref
  name="HRRT05">
  M. G. Hinchey, C. A. Rouff, J. L. Rash and W. F. Truszkowski (2005)
  'Requirements of an Integrated Formal Method for Intelligent Swarms', 
  in ''Proceedings of FMICS'05, September 5–6, 2005, Lisbon, Portugal''. 
  Association for Computing Machinery, pp. 125-133.</ref>