Abstract
The IEC 61508 standard recognizes the programming languages defined in IEC 61131-3 as being appropriate for safety-related applications, and suggests the use of static data type analysis of the source code. In this context, we have added a data type semantic verifier to the MatIEC compiler - an open source ST, IL and SFC code translator to ANSI C. In so doing, we have identified several issues related to the definition of the semantics of the IL and ST programming languages, as well as with the data type model defined in IEC 61131-3. In this paper we describe the issues we uncovered, explain how the data type static analyzer of the MatIEC was implemented, explain the options we took, and suggest how the IEC 61131-3 standard could be made more explicit.

Abstract
At the present time virtual communities are overspread in the web, providing users a cyber-place to share common purposes and interact with other users around the world. Interaction in these environments grapple with new challenges concerning to provide their users better tools to interact and fulfil their goals. In this context we propose a model to create regulated interaction environments based on the theatre metaphor: the Social Theatres. A dynamic multi-layer software architecture (ASTeaS) was developed to support this web-based interaction model, allowing easy construction of such social interaction spaces and adaptation to users' devices requirements. In this paper we discuss the usage of interaction regulation in virtual environments supported by the Social Theatres model and evaluate some aspects of the users interaction in two different case study scenarios.

Abstract
This paper addresses the scenario of multi-release anonymization of datasets. We consider dynamic datasets where data can be inserted and deleted, and view this scenario as a case where each release is a small subset of the dataset corresponding, for example, to the results of a query. Compared to multiple releases of the full database, this has the obvious advantage of faster anonymization. We present an algorithm for post-processing anonymized queries that prevents anonymity attacks using multiple released queries. This algorithm can be used with several distinct protection principles and anonymization algorithms, which makes it generic and flexible. We give an experimental evaluation of the algorithm and compare it to m-invariance both in terms of efficiency and data quality. To this end, we propose two data quality metrics based on Shannon's entropy, and show that they can be seen as a refinement of existing metrics. © 2012 ACM.

Abstract
We introduce a simple agent construct associated to a named local database and a "Twitter-style"weak inheritance mechanism between local agents. On top of a remote predicate call layer, connecting distributed agent spaces, we build a replication mechanism allowing agents "visiting" remote spaces to expose their computational capabilities to non-local followers. The resulting protocol has the remarkable property that only updates to the state of the agents are sent over the network through transactional remote predicate calls guaranteed to always terminate, and therefore spawning of multiple threads can be avoided. At the same time, calls to a visiting agent's code by its followers are always locally executed, resulting in performance gains and reduced communication efforts. Copyright 2012 ACM.

Abstract
In this paper we propose a hybrid music recommender system, which combines usage and content data. We describe an online evaluation experiment performed in real time on a commercial music web site, specialised in content from the very long tail of music content. We compare it against two stand-alone recommenders, the first system based on usage and the second one based on content data. The results show that the proposed hybrid recommender shows advantages with respect to usage- and content-based systems, namely, higher user absolute acceptance rate, higher user activity rate and higher user loyalty. Copyright is held by the International World Wide Web Conference Committee (IW3C2).

Abstract
Hydro energy represents a priority in the energy policy of Portugal, with the aim of decreasing the dependence on fossil fuels. In this context, optimal hydro scheduling acquires added significance in moving towards a sustainable environment. A mixed-integer nonlinear programming approach is considered to enable optimal hydro scheduling for the short-term time horizon, including the effect of head on power production, start-up costs related to the units, multiple regions of operation, and constraints on discharge variation. As new contributions to the field, market uncertainty is introduced in the model via price scenarios and risk management is included using Conditional Value-at-Risk to limit profit volatility. Moreover, plant scheduling and pool offering by the hydro power producer are simultaneously considered to solve a realistic cascaded hydro system.