Maria Alberta Alberti

A neural algorithm for MAX-2SAT: performance analysis and circuit implementation

Abstract A neural algorithm for solving approximately the maximum 2-satisfiability problem is presented and its performance is analysed: the worst case relative error is 0.25 and the computation time is bounded by nm 4 , where n is the number of variables and m the number of clauses of a problem instance. Simulation experiments show a very good average case performance. We design a uniform family of circuits of small size and depth to implement the algorithm and present an efficient realization on field programmable gate arrays.

A semiotic approach to narrative manipulation

In the design of multimedia communication artifacts few, if any, tools support the early stage of a creative process: the heuristic project. In this work we give a proof of concept of an application addressed to a specific kind of heuristic project: given the logical sequence of episodes of a narrative, the fabula, the goal is to obtain different plots expressed in multi-modal language. The case study is provided by the task of transposing a written synopsis to the multi-modal language of a movie. We adopted the semiotic theory of Greimas to analyze the narrative and reveal its deep structure. The application enables users to interact with this structure in order to simulate and anticipate the effects of meaning resulting from their manipulation.

A neural circuit for the maximum 2-satisfiability problem

In this paper we discuss a uniform family of circuits, realizing neural networks to solve approximately the maximum 2-satisfiability problem. An implementation on FPGA for the problem instances of 16 variables and 480 clauses is presented. The circuit shows a good performance solving problem instances in 20 /spl mu/s with relative error less than 0.003.<<ETX>>

Towards object-oriented modelling of euclidean geometry

This paper presents an object-oriented approach to interactive modelling of geometric objects. The objects are specified by geometric constructions that are built by mimicing the compass-and-ruler manual approach in a direct manipulation graphical interface. The system adopts a programming-by-example paradigm to enrich construction methods incrementally. New constructions can be used to define new classes of objects or new methods for an existing class. Messages exchanged among objects specify geometric relationships among entities. Messages sent at construction time implicitly form a relationship network, which is preserved during subsequent geometric transformations, so that geometric constraints can be satisfied without resorting to numerical methods. The prototype GEObject is implemented under Actor in a Windows 3.0 environment.

Knowledge Representation in a Learning Environment for Euclidean Geometry

Virtual laboratories uncover some new problems of system and interface design because they can induce misleading mental images of the subject matter. Rooting a system design on the analysis of the knowledge domain allows a clean internal design. Object-oriented methodology to represent the geometric knowledge and Petri nets formalism to represent geometric constructions helped us to solve the conceptual problem of formalizing the knowledge structure, minimizing inconsistencies between the content matter and its representation. The prototypal system implemented adopts a “programming by example” paradigm to incrementally enrich construction methods; new constructions can be used to define new classes of objects or new methods for an existing class.

Modelling constrained geometric objects with OBJSA nets

In this paper we introduce a formal specification of the problem of modelling geometric constrained objects adopting OBJSA nets, a high level Petri net. The geometric objects are defined imperatively while constructing them. The approach is innovative in that it solves constraints during manipulation, propagating messages among the objects involved in the geometric figure and it does not require numerical techniques. The formalization of the geometric constructions with OBJSA nets has been an important step to validate the system and in particular the constraint maintenance algorithm. Each class of the system is modelled by a OBJSA component and their compositions allows to describe a generic construction. The algorithm specified in OBJSA can be simulated in the ONE (OBJSA Net Environment) environment.

Genova 2004: a test-bed for industrial design students to integrate cultural content and information technologies in cross-media platforms

The event Genoa 20041 is a tantalizing occasion to stimulate students enrolled in a five-year program in Industrial Design at Politecnico di Milano to produce original content to compliment the official program and to experiment with technology using a variety of media. The official Genoa 2004 calendar is structured in three main themes: Genoa, the City of Arts; the Capital of the Sea; and the Contemporary City. Students had to choose one of the three areas, make proposals of new concepts of cultural products and services, and implement the prototype.

Controsenso, but not too much: digital artifacts to ease communication and exchange with seeing-impaired people

Controsenso means contradiction or counter-sense and alludes to the idea, only apparently strange, to have a blind person as your guide through their home town. Controsenso: Genoa as you have never seen it, is a virtual tour of the city of Genoa to reveal in poetry the everyday life experience of seeing-impaired people. The choice is story telling through sound and images of what blind people see and perceive of their city. It conveys strong feelings in terms of noises, smells, lights and shadows, and pavement and walls textures. These represent known objects, places, people and shops: the thousands of details that go unseen at a conscious level for most of us.