17,042 research outputs found
On the role of domain ontologies in the design of domain-specific visual modeling langages
Domain-Specific Visual Modeling Languages should provide notations and abstractions that suitably support problem solving in well-defined application domains. From their user’s perspective, the language’s modeling primitives must be intuitive and expressive enough in capturing all intended aspects of domain conceptualizations. Over the years formal and explicit representations of domain conceptualizations have been developed as domain ontologies. In this paper, we show how the design of these languages can benefit from conceptual tools developed by the ontology engineering community
An Approach to Select Cost-Effective Risk Countermeasures Exemplified in CORAS
Risk is unavoidable in business and risk management is needed amongst others
to set up good security policies. Once the risks are evaluated, the next step
is to decide how they should be treated. This involves managers making
decisions on proper countermeasures to be implemented to mitigate the risks.
The countermeasure expenditure, together with its ability to mitigate risks, is
factors that affect the selection. While many approaches have been proposed to
perform risk analysis, there has been less focus on delivering the prescriptive
and specific information that managers require to select cost-effective
countermeasures. This paper proposes a generic approach to integrate the cost
assessment into risk analysis to aid such decision making. The approach makes
use of a risk model which has been annotated with potential countermeasures,
estimates for their cost and effect. A calculus is then employed to reason
about this model in order to support decision in terms of decision diagrams. We
exemplify the instantiation of the generic approach in the CORAS method for
security risk analysis.Comment: 33 page
Embedding object-oriented design in system engineering
The Unified Modeling Language (UML) is a collection of techniques intended to document design decisions about software. This contrasts with systems engineering approaches such as for exampleStatemate and the Yourdon Systems Method (YSM), in which the design of an entire system consisting of software and hardware can be documented. The difference between the system- and the software level is reflected in differences between execution semantics as well as in methodology. In this paper, I show how the UML can be used as a system-level design technique. I give a conceptual framework for engineering design that accommodates the system- as well as the software level and show how techniques from the UML and YSM can be classified within this framework, and how this allows a coherent use of these techniques in a system engineering approach. These ideas are illustrated by a case study in which software for a compact dynamic bus station is designed. Finally, I discuss the consequences of this approach for a semantics of UML constructs that would be appropriate for system-level design
Symbolic Exact Inference for Discrete Probabilistic Programs
The computational burden of probabilistic inference remains a hurdle for
applying probabilistic programming languages to practical problems of interest.
In this work, we provide a semantic and algorithmic foundation for efficient
exact inference on discrete-valued finite-domain imperative probabilistic
programs. We leverage and generalize efficient inference procedures for
Bayesian networks, which exploit the structure of the network to decompose the
inference task, thereby avoiding full path enumeration. To do this, we first
compile probabilistic programs to a symbolic representation. Then we adapt
techniques from the probabilistic logic programming and artificial intelligence
communities in order to perform inference on the symbolic representation. We
formalize our approach, prove it sound, and experimentally validate it against
existing exact and approximate inference techniques. We show that our inference
approach is competitive with inference procedures specialized for Bayesian
networks, thereby expanding the class of probabilistic programs that can be
practically analyzed
A Fast Compiler for NetKAT
High-level programming languages play a key role in a growing number of
networking platforms, streamlining application development and enabling precise
formal reasoning about network behavior. Unfortunately, current compilers only
handle "local" programs that specify behavior in terms of hop-by-hop forwarding
behavior, or modest extensions such as simple paths. To encode richer "global"
behaviors, programmers must add extra state -- something that is tricky to get
right and makes programs harder to write and maintain. Making matters worse,
existing compilers can take tens of minutes to generate the forwarding state
for the network, even on relatively small inputs. This forces programmers to
waste time working around performance issues or even revert to using
hardware-level APIs.
This paper presents a new compiler for the NetKAT language that handles rich
features including regular paths and virtual networks, and yet is several
orders of magnitude faster than previous compilers. The compiler uses symbolic
automata to calculate the extra state needed to implement "global" programs,
and an intermediate representation based on binary decision diagrams to
dramatically improve performance. We describe the design and implementation of
three essential compiler stages: from virtual programs (which specify behavior
in terms of virtual topologies) to global programs (which specify network-wide
behavior in terms of physical topologies), from global programs to local
programs (which specify behavior in terms of single-switch behavior), and from
local programs to hardware-level forwarding tables. We present results from
experiments on real-world benchmarks that quantify performance in terms of
compilation time and forwarding table size
Timed Automata Semantics for Visual e-Contracts
C-O Diagrams have been introduced as a means to have a more visual
representation of electronic contracts, where it is possible to represent the
obligations, permissions and prohibitions of the different signatories, as well
as what are the penalties in case of not fulfillment of their obligations and
prohibitions. In such diagrams we are also able to represent absolute and
relative timing constraints. In this paper we present a formal semantics for
C-O Diagrams based on timed automata extended with an ordering of states and
edges in order to represent different deontic modalities.Comment: In Proceedings FLACOS 2011, arXiv:1109.239
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