26,706 research outputs found
A Note on the Expressiveness of BIP
We extend our previous algebraic formalisation of the notion of
component-based framework in order to formally define two forms, strong and
weak, of the notion of full expressiveness. Our earlier result shows that the
BIP (Behaviour-Interaction-Priority) framework does not possess the strong full
expressiveness. In this paper, we show that BIP has the weak form of this
notion and provide results detailing weak and strong full expressiveness for
classical BIP and several modifications, obtained by relaxing the constraints
imposed on priority models.Comment: In Proceedings EXPRESS/SOS 2016, arXiv:1608.0269
Towards a Theory of Glue
We propose and study the notions of behaviour type and composition operator
making a first step towards the definition of a formal framework for studying
behaviour composition in a setting sufficiently general to provide insight into
how the component-based systems should be modelled and compared. We illustrate
the proposed notions on classical examples (Traces, Labelled Transition Systems
and Coalgebras). Finally, the definition of memoryless glue operators, takes us
one step closer to a formal understanding of the separation of concerns
principle stipulating that computational aspects of a system should be
localised within its atomic components, whereas coordination layer responsible
for managing concurrency should be realised by memoryless glue operators.Comment: In Proceedings ICE 2012, arXiv:1212.345
3-D facial expression representation using B-spline statistical shape model
Effective representation and recognition of human faces are essential in a number of applications including human-computer interaction (HCI), bio-metrics or video conferencing. This paper presents initial results obtained for a novel method of 3-D facial expressions representation based on the shape space vector of the statistical shape model. The statistical shape model is constructed based on the control points of the B-spline surfaces of the train-ing data set. The model fitting for the data is achieved by a modified iterative closest point (ICP) method with the surface deformations restricted to the es-timated shape space. The proposed method is fully automated and tested on the synthetic 3-D facial data with various facial expressions. Experimental results show that the proposed 3-D facial expression representation can be potentially used for practical applications
Intuitions and the modelling of defeasible reasoning: some case studies
The purpose of this paper is to address some criticisms recently raised by
John Horty in two articles against the validity of two commonly accepted
defeasible reasoning patterns, viz. reinstatement and floating conclusions. I
shall argue that Horty's counterexamples, although they significantly raise our
understanding of these reasoning patterns, do not show their invalidity. Some
of them reflect patterns which, if made explicit in the formalisation, avoid
the unwanted inference without having to give up the criticised inference
principles. Other examples seem to involve hidden assumptions about the
specific problem which, if made explicit, are nothing but extra information
that defeat the defeasible inference. These considerations will be put in a
wider perspective by reflecting on the nature of defeasible reasoning
principles as principles of justified acceptance rather than `real' logical
inference.Comment: Proceedings of the 9th International Workshop on Non-Monotonic
Reasoning (NMR'2002), Toulouse, France, April 19-21, 200
Musings on Encodings and Expressiveness
This paper proposes a definition of what it means for one system description
language to encode another one, thereby enabling an ordering of system
description languages with respect to expressive power. I compare the proposed
definition with other definitions of encoding and expressiveness found in the
literature, and illustrate it on a case study: comparing the expressive power
of CCS and CSP.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244
Simplicity-Expressiveness Tradeoffs in Mechanism Design
A fundamental result in mechanism design theory, the so-called revelation
principle, asserts that for many questions concerning the existence of
mechanisms with a given outcome one can restrict attention to truthful direct
revelation-mechanisms. In practice, however, many mechanism use a restricted
message space. This motivates the study of the tradeoffs involved in choosing
simplified mechanisms, which can sometimes bring benefits in precluding bad or
promoting good equilibria, and other times impose costs on welfare and revenue.
We study the simplicity-expressiveness tradeoff in two representative settings,
sponsored search auctions and combinatorial auctions, each being a canonical
example for complete information and incomplete information analysis,
respectively. We observe that the amount of information available to the agents
plays an important role for the tradeoff between simplicity and expressiveness
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