5,914 research outputs found
On the Expressiveness of Joining
The expressiveness of communication primitives has been explored in a common
framework based on the pi-calculus by considering four features: synchronism
(asynchronous vs synchronous), arity (monadic vs polyadic data), communication
medium (shared dataspaces vs channel-based), and pattern-matching (binding to a
name vs testing name equality vs intensionality). Here another dimension
coordination is considered that accounts for the number of processes required
for an interaction to occur. Coordination generalises binary languages such as
pi-calculus to joining languages that combine inputs such as the Join Calculus
and general rendezvous calculus. By means of possibility/impossibility of
encodings, this paper shows coordination is unrelated to the other features.
That is, joining languages are more expressive than binary languages, and no
combination of the other features can encode a joining language into a binary
language. Further, joining is not able to encode any of the other features
unless they could be encoded otherwise.Comment: In Proceedings ICE 2015, arXiv:1508.04595. arXiv admin note:
substantial text overlap with arXiv:1408.145
Phenomenology of retained refractoriness: On semi-memristive discrete media
We study two-dimensional cellular automata, each cell takes three states:
resting, excited and refractory. A resting cell excites if number of excited
neighbours lies in a certain interval (excitation interval). An excited cell
become refractory independently on states of its neighbours. A refractory cell
returns to a resting state only if the number of excited neighbours belong to
recovery interval. The model is an excitable cellular automaton abstraction of
a spatially extended semi-memristive medium where a cell's resting state
symbolises low-resistance and refractory state high-resistance. The medium is
semi-memristive because only transition from high- to low-resistance is
controlled by density of local excitation. We present phenomenological
classification of the automata behaviour for all possible excitation intervals
and recovery intervals. We describe eleven classes of cellular automata with
retained refractoriness based on criteria of space-filling ratio, morphological
and generative diversity, and types of travelling localisations
Properties of Distributed Time Arc Petri Nets
In recent work we started a research on a distributed-timed extension of Petri nets where time parameters are associated with tokens and arcs carry constraints that qualify the age of tokens required for enabling. This formalism enables to model e.g. hardware architectures like GALS. We give a formal definition of process semantics for our model and investigate several properties of local versus global timing: expressiveness, reachability and coverability
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