Proofs of observational equivalence of behaviour expressions in
Milner's Calculus of Communicating Systems can be quite lengthy,
and as larger and more practical systems of agents are considered
the need for shorter proof techniques becomes more important. In
this thesis a number of results about the calculus are proved
which give rise to give more natural techniques. Three
principal areas of research are presented:(i) A study of strong confluence and determinacy is made,
extending Hilner's work to the whole calculus - the
appropriate modifications to take value-passing into account
are motivated and defined, and a strong confluence theorem
is proved. It is shown that a useful subcalculus of CCS is
strongly confluent.(ii) An investigation into criteria for uniqueness of solution of
equations pf the form b = Fib] is performed. To do this a
concept of derivations of an agent A "causing" derivations
of FlAl is defined; using this, conditions are imposed on F
which imply uniqueness, and a study follows of how these
conditions relate to the structure of F.(iii) By using an alternative, stronger, definition of
observational equivalence as a maximal fixed point it is
found that equivalences can be demonstrated by constructing
bisimulations between agents, and results leading to an
algorithm for such constructions are presented. Also, using
this alternative definition a weaker form of confluence can
be defined very easily, and this is investigated.The theoretical material in this thesis is supplemented by
examples demonstrating how the results proved can be applied to
give proof techniques for use within the calculus
