In this paper, a block-based watermarking scheme based on the Singular Value Decomposition (SVD) is proposed. Our watermark, a pseudo-random Gaussian sequence, is embedded by modifying the angles formed by the right singular vectors of each block of the original image. The orthogonality property of the right singular vector matrix is preserved during the… (More)
In this work 1 we present an approach for the formal specification and verification of the reconfiguration protocols in Grid component systems. We consider Fractal, a modular and extensible component model. As a specification tool we invoke a specific temporal language, separated clausal normal form, which has been shown to be capable of expressing any ECTL… (More)
Providing valuable recommendations in the DVR domain is quite straightforward when enough information about users and/or contents is known. In this work, we discuss the possibility of recommending future live events without knowing anything else but past user programmed recording schedules .
Recommendation Systems can be one of the killer applications for a new generation of PVRs. Unfortunately, these systems do not apply directly to this domain because of the unreliability of EPGs and registrations set on temporal basis instead of discrete objects. We propose a method for discretizing temporal and volatile events and the preliminary version of… (More)
In this paper we present a natural deduction calculus for branching-time deontic logic, a combination of the branching-time logic CTL and deontic modalities. We show how this new proof technique can be applied as a reasoning tool in modeling dynamic normative systems, namely, Grid Component System. We formally define behaviour of state-ful components and a… (More)
Is it possible to implement practical Internet Polls that fulfill even the weakest security requirements? The technology available today would lead to a negative answer, because of the following practical constraints: standard, unmodified browsers are used, it is not economically possible to distribute certificates or even just user names and passwords,… (More)
This work attempts to find a practical and effective solution to prevent massive and automated access to web resources. The basic idea is to avoid that a large quantity of contents is transferred without explicit authorization. This is generally possible due to the widespread use of automated tools, widely exploited to achieve an almost infinite range of… (More)