1,704 research outputs found
A Note on Limited Pushdown Alphabets in Stateless Deterministic Pushdown Automata
Recently, an infinite hierarchy of languages accepted by stateless
deterministic pushdown automata has been established based on the number of
pushdown symbols. However, the witness language for the n-th level of the
hierarchy is over an input alphabet with 2(n-1) elements. In this paper, we
improve this result by showing that a binary alphabet is sufficient to
establish this hierarchy. As a consequence of our construction, we solve the
open problem formulated by Meduna et al. Then we extend these results to
m-state realtime deterministic pushdown automata, for all m at least 1. The
existence of such a hierarchy for m-state deterministic pushdown automata is
left open
Relating BIP and Reo
Coordination languages simplify design and development of concurrent systems.
Particularly, exogenous coordination languages, like BIP and Reo, enable system
designers to express the interactions among components in a system explicitly.
In this paper we establish a formal relation between BI(P) (i.e., BIP without
the priority layer) and Reo, by defining transformations between their semantic
models. We show that these transformations preserve all properties expressible
in a common semantics. This formal relation comprises the basis for a solid
comparison and consolidation of the fundamental coordination concepts behind
these two languages. Moreover, this basis offers translations that enable users
of either language to benefit from the toolchains of the other.Comment: In Proceedings ICE 2015, arXiv:1508.0459
Undecidability of model-checking branching-time properties of stateless probabilistic pushdown process
In this paper, we settle a problem in probabilistic verification of
infinite--state process (specifically, {\it probabilistic pushdown process}).
We show that model checking {\it stateless probabilistic pushdown process}
(pBPA) against {\it probabilistic computational tree logic} (PCTL) is
undecidable.Comment: Author's comments on referee's report added, Interestin
Failover in cellular automata
A cellular automata (CA) configuration is constructed that exhibits emergent
failover. The configuration is based on standard Game of Life rules. Gliders
and glider-guns form the core messaging structure in the configuration. The
blinker is represented as the basic computational unit, and it is shown how it
can be recreated in case of a failure. Stateless failover using primary-backup
mechanism is demonstrated. The details of the CA components used in the
configuration and its working are described, and a simulation of the complete
configuration is also presented.Comment: 16 pages, 15 figures and associated video at
http://dl.dropbox.com/u/7553694/failover_demo.avi and simulation at
http://dl.dropbox.com/u/7553694/failover_simulation.ja
A state of a dynamic computational structure distributed in an environment: a model and its corollaries
Currently there is great interest in computational models consisting of
underlying regular computational environments, and built on them distributed
computational structures. Examples of such models are cellular automata,
spatial computation and space-time crystallography. For any computational model
it is natural to define a functional equivalence of different but related
computational structures. In the finite automata theory an example of such
equivalence is automata homomorphism and, in particular, automata isomorphism.
If we continue to stick to the finite automata theory, a fundamental question
arise, what a state of a distributed computational structure is. This work is
devoted to particular solution of the issue.Comment: 11 pages, 5 figure
Refinement Calculus of Reactive Systems
Refinement calculus is a powerful and expressive tool for reasoning about
sequential programs in a compositional manner. In this paper we present an
extension of refinement calculus for reactive systems. Refinement calculus is
based on monotonic predicate transformers, which transform sets of post-states
into sets of pre-states. To model reactive systems, we introduce monotonic
property transformers, which transform sets of output traces into sets of input
traces. We show how to model in this semantics refinement, sequential
composition, demonic choice, and other semantic operations on reactive systems.
We use primarily higher order logic to express our results, but we also show
how property transformers can be defined using other formalisms more amenable
to automation, such as linear temporal logic (suitable for specifications) and
symbolic transition systems (suitable for implementations). Finally, we show
how this framework generalizes previous work on relational interfaces so as to
be able to express systems with infinite behaviors and liveness properties
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