Past Seminars
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Tiago Reis
Coin Flipping Over the Telephone
Thursday, 10th May 2007Is it possible for two people to flip a coin over the telephone? Can this be done in such a way that whoever chooses "heads" or "tails" does not question the honesty of the other person?
In this seminar, I will present a solution to this problem and show why the participants can't cheat at coin flipping.
Lastly, I will use the Coin Flipping protocol to introduce the cryptographic notions of Bit Commitment and Oblivious Transfer and discuss some of their applications. -
Marco Volpe
Pillole di Logica Modale
(ovvero: Passeggiando per i mondi possibili)
Thursday, 24th May 2007Quando parliamo di logica, siamo solitamente (classicamente!) interessati a ragionare sulla verità o sulla falsità di un'affermazione. Tuttavia, in molti casi, questo non ci basta. Potremmo ad esempio voler stabilire se un'affermazione sia necessaria (oppure possibile, obbligatoria, proibita, "ritenuta" vera, vera da un certo punto in poi, vera ad un certo istante, vera per sempre...). In questo seminario, si fornirà un'introduzione alle idee di base della Logica Modale, che nasce proprio dal bisogno espresso sopra. In particolare, l'attenzione sarà rivolta agli aspetti semantici di tale logica, tipicamente modellati tramite strutture di mondi possibili (semantica alla Kripke). Infine, si farà qualche cenno alla definizione di sistemi deduttivi etichettati, nei quali l'idea dei mondi possibili viene utilizzata esplicitamente all'interno della sintassi.
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Enrico Visentini
Abstract Interpretation a prima vista
Thursday, 7th June 2007Abstract Interpretation is a very general methodology for modeling approximation processes algebraically. It has provided promising results in the approximation of the semantics of discrete dynamic systems.
In this seminar I will introduce the basic notions of Abstract Interpretation by showing how to abstract integer numbers by their sign. Through a couple of functions we will be able to correlate the concrete domain of integers and the abstract domain of signs. Then we will see how concrete-domain functions can be correctly turned into abstract-domain functions. Terminology and notations will be almost left out, whereas lots of figures will convey (hopefully) all the basic intuitions.
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Andrea Turrini
Approximated Computationally Bounded Simulation Relations for Probabilistic Automata
Thursday, 21th June 2007We study simulation relations for Probabilistic Automata that require transitions to be matched up to negligible sets provided that computation lengths are polynomially bounded. These relations are meant to provide rigorous grounds to parts of correctness proofs for cryptographic protocols that are usually carried out by semi-formal arguments. We illustrate our ideas by recasting a correctness proof of Bellare and Rogaway based on the notion of matching conversation.
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Margherita Zorzi
Beam me up, Scotty! A journey with Quantum Teleportation.
Thursday, 5th July 2007Come farà il Capitano Kirk a mandare un messaggio al Signor Spock senza essere intercettato dai Romulani? Ma usando il Teletrasporto Quantistico! Ovvero, un affascinante protocollo del Quantum Computing che permette di comunicare una superinformazione quantistica (il qubit) inviando semplicemente dei bit... Il segreto: gli stati aggrovigliati EPR (dove E sta per Einstein).. Quindi, grazie ad Albert anche per questo e benvenuti ai confini della Galassia.
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Davide Zerbato
Deformable Models In Surgical Simulators
Thursday, 19th July 2007Surgical simulators rely on deformable models to render realistic, physics-based environments. It is not difficult to mimic the behaviour of soft tissues. However, when the computation of deformable objects is required at high rates a tradeoff has to be chosen between realism and speed.
In this talk I will introduce the problems that are related to the simulation of soft human organs, from the extraction of the shape from medical images to the implementation of the temporal integrator, and how we are facing them in Altair lab for the development of a prototype of surgical simulator.
Vicious and bloody images and video will be left out whereas lots of movies will present the state of the art in surgical simulation. -
Luca Irsara
An Uncalibrated View-Synthesis Pipeline
Thursday, 6th September 2007View synthesis consists in acquiring some reference images of a given scene and rendering new images of the same scene as if they were taken from a virtual viewpoint which is different from all the viewpoints of the reference images.
In this talk I will deal with the process of view synthesis based on the relative affine structure. In particular, I will describe a complete pipeline that, starting with uncalibrated images, produces a virtual sequence with viewpoint control. -
Alessandro Perina
Tecniche di machine learning per gli studi di associazione: dai genotipi alle malattie complesse
Thursday, 20th September 2007Gli esseri umani differiscono per lo 0.1% dei loro genomi. In questa piccola percentuale di variazione sono codificate le nostre predisposizioni a malattie complesse come asma, ipertensione e malattie cardiovascolari. Esaminando in individui sani e malati le variazioni nei geni che si suppone abbiano a che fare con una data malattia, possiamo tentare di identificare quali configurazioni genetiche sono associate alla malattia. Questo tipo di studi sono chiamati studi di associazione.
In questo MiDi talk verrà illustrato brevemente il nostro sistema genetico. In seguito verrà spiegato cosa siano genotipi, aplotipi e single nucleotide polimorphism (SNP) e perché e come questi siano legati alle malattie complesse. Verrà quindi illustrato cosa siano gli studi di associazioni, quali siano i sotto-problemi principali da risolvere quando si affrontano tali studi e come le tecniche di machine learning ci possano venire in aiuto per risolvere tali problemi.
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Eleonora Sibilio
Understanding Trust Management Systems
Thursday, 11th October 2007, at 14h00 in "Sala Verde"Trust, defined as the expectation that an entity has to respect the behaviour of another entity, has became popular in recent years, because existing authorization mechanisms fail to provide powerful and robust tools for handling security in the setting of distributed systems. Often in these systems (i.e. Internet) safety critical decisions have to be made under a partial knowledge: for example, identity-based authentications are inadequate in Internet, where identities are usually not known. The trust management approach is a possible answer to these limitations, specifying and interpreting security policies, credentials and relationships to take critical decisions and allow direct authorizations.
In this talk, I will introduce the notion of trust. I will present a very flexible mathematical framework for easily understanding and comparing trust management systems. The framework defines the semantics of a trust management engine via a least fixpoint in a lattice, which, in some situations, leads to an efficient implementation.
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Alberto Castellini
Comparing Models in Computational Systems Biology
Thursday, 31th October 2007, at 12h00 in "Sala Verde"Computational systems biology aims to assist biology and medicine in systems understanding by providing computational approaches to knowledge discovery and simulation-based analysis. Metabolic P systems are a special class of P systems developed to model dynamics of biological phenomena related to metabolism and signaling transduction in the living cell. The main target of this model is to give an intuitive representation of biochemical pathways in order to facilitate the comprehension of biological mechanisms. A new notation of MP graphs will be defined as a graphical representation of MP systems and the graphical user interface we devised to draw MP graphs while working with our MP simulator Psim will be described. We will propose also a comparison between MP systems and Hybrid Functional Petri Nets (HFPN), which are an extension of Petri nets for biopathways simulation, to highlight several similarities between the two formalisms. Finally, a definition of equivalence between MP systems and HFPN will conclude the talk.