The
denotational semantics of the Actor model is the subject of denotational
domain theory for
Actors. The historical development of this subject is recounted in .
Actor fixed point semantics
The denotational theory of computational system semantics is concerned with finding mathematical objects that represent what systems do. Collections of such objects are called
domains. The
Actor uses the domain of event diagram scenarios. It is usual to assume some properties of the domain, such as the existence of limits of chains (see
cpo) and a bottom element. Various additional properties are often reasonable and helpful: the article on
domain theory has more details.
A domain is typically a
partial order, which can be understood as an order of definedness. For instance, given event diagram scenarios <tt>x</tt> and <tt>y</tt>, one might let "<tt>x≤y</tt>" mean that "<tt>y</tt> extends the computations <tt>x</tt>".
The mathematical denotation denoted by a system <tt>S</tt> is found by constructing increasingly better approximations from an initial empty denotation called <tt>⊥<sub>S</sub></tt> using some denotation approximating function <tt>
progression<sub>S</sub></tt> to construct a denotation (meaning ) for <tt>S</tt> as follows:
- :<tt>Denote<sub>S</sub> ≡ ⊔<sub>i∈ω</sub>......
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