Contexts, work processes, and workspaces

In this paper a framework for the conceptual modelling of organizational contexts is provided and it is embodied into an extension of the TOSCA organizational handbook.The context of a work process is relevant since the effectiveness of the cooperation among its actors is highly dependent on their awareness of it. It requires, on the one hand, that the context is made available in terms of visibility and/or transparency; on the other, that at any time a selection is made so that only what is relevant to the context is provided, leaving the rest in the background. With respect to the first requirement a model of the organizational context is needed, so that all the information regarding its dimensions can be linked together. With respect to the second requirement, a work process model provides some guidelines for designing a system offering a selective access to the context of a work process. The workspace metaphor is a good paradigm to make that information ready at hand, since it is the natural framework within which people do their work.     

A Theorem and Its Different Proofs: History,Mathematics Education,and the Semiotic-Cultural Perspective

Abstract

Several studies claim that integrating the history of mathematics into mathematics education is an important matter. In this article, some theoretical approaches are presented and the importance of the correct cultural contextualization is emphasized. Our purpose is to discuss, from an educational viewpoint, the problem of knowledge development within specific cultural contexts; cultural aspects play a cognitive and epistemological role in the way we think mathematically. More specifically, we provide a comparison of some strategies used by mathematicians in different periods in order to prove that primes are infinitely many. We conclude that historical examples should be understood in their cultural and social context and that the standards of symbolization and rigor depend on this context. In order to emphasize the use of history in education as a real tool for the teacher, we propose an outline of educational opportunities. The perspective presented requires a good level of epistemological skill on the part of teachers; therefore, it should be considered in teacher education.     

Applying real-time interface and calculus for dynamic power management in hard real-time systems

Power dissipation has been an important design issue for a wide range of computer systems in the past decades. Dynamic power consumption due to signal switching activities and static power consumption due to leakage current are the two major sources of power consumption in a CMOS circuit. As CMOS technology advances towards deep sub-micron domain, static power dissipation is comparable to or even more than dynamic power dissipation. This article explores how to apply dynamic power management to reduce static power for hard real-time systems. We propose online algorithms that adaptively control the power mode of a system, procrastinating the processing of arrived events as late as possible. To cope with multiple event streams with different characteristics, we provide solutions for preemptive earliest-deadline-first and fixed-priority scheduling policies. By adopting a worst-case interval-based abstraction, our approach can not only tackle arbitrary event arrivals, e.g., with burstiness, but also guarantee hard real-time requirements with respect to both timing and backlog constraints. We also present extensive simulation results to demonstrate the effectiveness of our approaches.     

Teaching a humanoid robot to draw ‘Shapes’

The core cognitive ability to perceive and synthesize ‘shapes’ underlies all our basic interactions with the world, be it shaping one’s fingers to grasp a ball or shaping one’s body while imitating a dance. In this article, we describe our attempts to understand this multifaceted problem by creating a primitive shape perception/synthesis system for the baby humanoid iCub. We specifically deal with the scenario of iCub gradually learning to draw or scribble shapes of gradually increasing complexity, after observing a demonstration by a teacher, by using a series of self evaluations of its performance. Learning to imitate a demonstrated human movement (specifically, visually observed end-effector trajectories of a teacher) can be considered as a special case of the proposed computational machinery. This architecture is based on a loop of transformations that express the embodiment of the mechanism but, at the same time, are characterized by scale invariance and motor equivalence. The following transformations are integrated in the loop: (a) Characterizing in a compact, abstract way the ‘shape’ of a demonstrated trajectory using a finite set of critical points, derived using catastrophe theory: Abstract Visual Program (AVP); (b) Transforming the AVP into a Concrete Motor Goal (CMG) in iCub’s egocentric space; (c) Learning to synthesize a continuous virtual trajectory similar to the demonstrated shape using the discrete set of critical points defined in CMG; (d) Using the virtual trajectory as an attractor for iCub’s internal body model, implemented by the Passive Motion Paradigm which includes a forward and an inverse motor model; (e) Forming an Abstract Motor Program (AMP) by deriving the ‘shape’ of the self generated movement (forward model output) using the same technique employed for creating the AVP; (f) Comparing the AVP and AMP in order to generate an internal performance score and hence closing the learning loop. The resulting computational framework further combines three crucial streams of learning: (1) motor babbling (self exploration), (2) imitative action learning (social interaction) and (3) mental simulation, to give rise to sensorimotor knowledge that is endowed with seamless compositionality, generalization capability and body-effectors/task independence. The robustness of the computational architecture is demonstrated by means of several experimental trials of gradually increasing complexity using a state of the art humanoid platform.     

Moving-horizon state estimation for nonlinear discrete-time systems: New stability results and approximation schemes

A moving-horizon state estimation problem is addressed for a class of nonlinear discrete-time systems with bounded noises acting on the system and measurement equations. As the statistics of such disturbances and of the initial state are assumed to be unknown, we use a generalized least-squares approach that consists in minimizing a quadratic estimation cost function defined on a recent batch of inputs and outputs according to a sliding-window strategy. For the resulting estimator, the existence of bounding sequences on the estimation error is proved. In the absence of noises, exponential convergence to zero is obtained. Moreover, suboptimal solutions are sought for which a certain error is admitted with respect to the optimal cost value. The approximate solution can be determined either on-line by directly minimizing the cost function or off-line by using a nonlinear parameterized function. Simulation results are presented to show the effectiveness of the proposed approach in comparison with the extended Kalman filter.     

Force feedback exploiting tactile and proximal force/torque sensing

The paper addresses the problem of measuring whole-body dynamics for a multiple-branch kinematic chain in presence of unknown external wrenches. The main result of the paper is to give a methodology for computing whole body dynamics by aligning a model of the system dynamics with the measurements coming from the available sensors. Three primary sources of information are exploited: (1) embedded force/torque sensors, (2) embedded inertial sensors, (3) distributed tactile sensors (i.e. artificial skin). In order to cope with external wrenches applied at continuously changing locations, we model the kinematic chain with a graph which dynamically adapts to the contact locations. Classical pre-order and post-order traversals of this dynamically evolving graph allow computing whole-body dynamics and estimate external wrenches. Theoretical results have been implemented in an open-source software library (iDyn) released under the iCub project. Experimental results on the iCub humanoid robot show the effectiveness of the proposed approach.     

Tracing Field‐Coherent Quad Layouts

Given a cross field over a triangulated surface we present a practical and robust method to compute a field aligned coarse quad layout over the surface. The method works directly on a triangle mesh without requiring any parametrization and it is based on a new technique for tracing field‐coherent geodesic paths directly on a triangle mesh, and on a new relaxed formulation of a binary LP problem, which allows us to extract both conforming quad layouts and coarser layouts containing t‐junctions. Our method is easy to implement, very robust, and, being directly based on the input cross field, it is able to generate better aligned layouts, even with complicated fields containing many singularities. We show results on a number of datasets and comparisons with state‐of‐the‐art methods.     

Social logics and expert systems

My goal is to emphasize the way we generally use the word logic and the sort of problems related to the definition of logic and the sort of problems related to the definition of logic. I also wish to underline the differences between human intelligence and artificial intelligence.I underline what, in my opinion, are the consequences for skill and knowledge transfer when using logic-based methodologies in landscapes deeply different from an input landscape. In this case I use, as a paradigm, the Indian way of logic, that has developed an original form of formal logic different from the Western logic.     

A prototype of an integrated coordination support system

UTUCS is a system for supporting a group of people (an office, a team, etc.) interconnected through a communication network in handling conversations carried on through different communication media. It has been developed with the aim of providing a good coordination support system that pairs the best computer-based tool a group may have in any situation (dispersed versus non dispersed, synchronous versus non synchronous) with the ability to switch from one to another, maintaining integrated and linked the information it creates. As UTUCS is a general system devoted to integrating conversations independently of the communication media exploited, it has been designed in such a way that it can be enhanced by developing a module for any communication medium that can be effectively supported by a computer network. Up to now the Electronic Mail module, the Face to Face Couple Colloquies module, and the Face to Face Group Meetings module have been implemented.