6,642 research outputs found
SCC: A Service Centered Calculus
We seek for a small set of primitives that might serve as a basis for formalising and programming service oriented applications over global computers. As an outcome of this study we introduce here SCC, a process calculus that features explicit notions of service definition, service invocation and session handling. Our proposal has been influenced by Orc, a programming model for structured orchestration of services, but the SCCâs session handling mechanism allows for the definition of structured interaction protocols, more complex than the basic request-response provided by Orc. We present syntax and operational semantics of SCC and a number of simple but nontrivial programming examples that demonstrate flexibility of the chosen set of primitives. A few encodings are also provided to relate our proposal with existing ones
Expressivity in Natural and Artificial Systems
Roboticists are trying to replicate animal behavior in artificial systems.
Yet, quantitative bounds on capacity of a moving platform (natural or
artificial) to express information in the environment are not known. This paper
presents a measure for the capacity of motion complexity -- the expressivity --
of articulated platforms (both natural and artificial) and shows that this
measure is stagnant and unexpectedly limited in extant robotic systems. This
analysis indicates trends in increasing capacity in both internal and external
complexity for natural systems while artificial, robotic systems have increased
significantly in the capacity of computational (internal) states but remained
more or less constant in mechanical (external) state capacity. This work
presents a way to analyze trends in animal behavior and shows that robots are
not capable of the same multi-faceted behavior in rich, dynamic environments as
natural systems.Comment: Rejected from Nature, after review and appeal, July 4, 2018
(submitted May 11, 2018
Expressiveness of Temporal Query Languages: On the Modelling of Intervals, Interval Relationships and States
Storing and retrieving time-related information are important, or even critical, tasks on many areas of Computer Science (CS) and in particular for Artificial Intelligence (AI). The expressive power of temporal databases/query languages has been studied from different perspectives, but the kind of temporal information they are able to store and retrieve is not always conveniently addressed. Here we assess a number of temporal query languages with respect to the modelling of time intervals, interval relationships and states, which can be thought of as the building blocks to represent and reason about a large and important class of historic information. To survey the facilities and issues which are particular to certain temporal query languages not only gives an idea about how useful they can be in particular contexts, but also gives an interesting insight in how these issues are, in many cases, ultimately inherent to the database paradigm. While in the area of AI declarative languages are usually the preferred choice, other areas of CS heavily rely on the extended relational paradigm. This paper, then, will be concerned with the representation of historic information in two well known temporal query languages: it Templog in the context of temporal deductive databases, and it TSQL2 in the context of temporal relational databases. We hope the results highlighted here will increase cross-fertilisation between different communities. This article can be related to recent publications drawing the attention towards the different approaches followed by the Databases and AI communities when using time-related concepts
- âŠ