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2224 discussions

[Settimanale] AVVISO DI SEMINARIO
by Giulia Curciarello 20 Nov '06

20 Nov '06

martedi' 21-11-2006 (15:00) - sala seminari Emanuele Delucchi (Universita' Zurigo) : Combinatorial remarks on a classical theorem of Pierre Deligne. (Or: The Importance of Being Simplicial) ABSTRACT: An arrangement is a set of linear hyperplanes in complex n-space. If the defining equations of the planes have real coefficient, the arrangement is called complexified. Deligne proved in 1972 that the complement of a complexified arrangement in n-dimensional complex space is aspherical (i.e., all higher homotopy group vanish) whenever a simple geometric condition ('simpliciality') on the associated real arrangement is satisfied. We will outline Deligne's proof, that consists of two steps. The first step is rather algebraic, the second is more topological in nature. We will approach the first step in Deligne's argument replacing the geometric condition of simpliciality by an equivalent combinatorial condition. Exploiting some combinatorial tools we can prove the converse of Deligne's statement, answering to a question posed by Luis Paris. Moreover, the standard techniques of topological combinatorics allow to state (and reprove) the second step of Deligne's proof in a very quick way. One might then suspect that a weaker condition than simpliciality suffices for the result to hold. We investigate a possible way towards this generalization. No special prerequisites are requested from the audience. _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] Fw: Avviso Seminario di Matematica, dr. Tanja Eisner (24.11.06)
by Giulia Curciarello 15 Nov '06

15 Nov '06

SEMINARIO DI MATEMATICA venerdì 24 novembre 2006 ore 11.00 Scuola Normale Superiore Pisa (Aula Mancini) Tanja Eisner University of Tübingen, Germany Terrà un seminario dal titolo: "Weak convergence for C0-semigroups" Tutti gli interessati sono invitati a partecipare. _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] Avviso - Colloquium di Dipartimento Nils Dencker
by Giulia Curciarello 15 Nov '06

15 Nov '06

martedi' 28-11-2006 (16:30) - Aula Magna Nils Dencker (Universita' di Lund) : Colloquium di Dipartimento -Solvability and the Nirenberg-Treves Conjecture In the 50's, the consensus was that all linear partial differential equations were solvable. Therefore, it came as a surprise 1957 when Hans Lewy found a non-solvable complex vector field. The vector field is a natural one, it is the Cauchy-Riemann operator on the boundary of a strictly pseudo-convex domain. The fact is that almost all linear PDE's are unsolvable, because of the Hörmander bracket condition. A rapid development in the 60's lead to the conjecture by Nirenberg and Treves in 1969: condition ($\Psi$) is necessary and sufficient for the solvability of partial differential equations of principal type. This is a condition which involves only the sign changes of the imaginary part of the highest order term of the operator along the bicharacteristics of the real part. The Nirenberg-Treves conjecture has recently been proved, see Annals of Mathematics, 163:2, 2006. We shall present the background and the ideas of the proof. ********************************************* Giulia Curciarello Segreteria Didattica tel-050-2213219 email: curciare(a)dm.unipi.it _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] errata corrige orario
by Giulia Curciarello 15 Nov '06

15 Nov '06

mercoledi' 29-11-2006 (16:00) - aula P1, I piano Polo Fibonacci Alberto D'Onofrio (IEO-Milano) : Immunoterapia dei tumori e competizione tumore-sistema immune: oncologia matematica e applicazioni cliniche _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] Avviso di seminario
by Giulia Curciarello 15 Nov '06

15 Nov '06

Mercoledi' 22 novembre 2006, ore 15.00, Sala Seminari Gianluca Pacienza (IRMA - Strasbourg) "La congettura di Green per curve eccezionali su superfici K3" Abstract: In un lavoro in collaborazione con Marian Aprodu dimostriamo lacongettura di Green per curve eccezionali su superfici K3. Tali curve figurano tra i pochi esempi di curve aventi dimensione di Clifford superiore o uguale a 3. Nel seminario presentero' le idee principali della dimostrazione, che si basa su un approccio infinitesimale introdotto da Pareschi,unito alla versione per curve nodali di un teorema di Hirschowitz-Ramanan-Voisin. _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] GIORNATA IN RICORDO DI ENNIO DE GIORGI
by Giulia Curciarello 15 Nov '06

15 Nov '06

Giovedi' 30 Novembre Aula magna del Dipartimento L.Tonelli GIORNATA IN RICORDO DI ENNIO DE GIORGI 10.00 Interventi di benvenuto 10.45 Giorgio Letta Introduzione 11.00 Sergio Spagnolo I classici teoremi di De Giorgi sulle equazioni differenziali 11.45 pausa 12.15 Antonio Marino "Anche la scienza ha bisogno di sognare" 13.00 intervallo 14.15 Marco Forti Le teorie fondazionali di Ennio De Giorgi 15.00 Luigi Ambrosio De Giorgi e la moderna Teoria Geometrica della Misura _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] avvisi di seminari
by Giulia Curciarello 14 Nov '06

14 Nov '06

mercoledi' 22-11-2006 (17:00) - Sala delle Riunioni Vicentiu Radulescu (University of Craiova, Romania) : Combined effects in the study of the Lane-Emden-Fowler equation Abstract. We study the Lane-Emden-Fowler equation with singular nonlinearity and convection term. We establish various existence, non-existence and uniqueness results. Our analysis takes into account the "competition" between the singular, smooth and convection terms, as well as the growth of the gradient term. Related bifurcation results and open problems are also given in this talk. *********************************************************************************** mercoledi' 29-11-2006 (15:00) - aula P1, I piano Polo Fibonacci Generoso Bevilacqua (Dip. di Oncologia- Divisione di Anatomia Patologica) : Ciclo cellulare e cancro *********************************************************************************** mercoledi' 29-11-2006 (18:00) - aula P1, I piano Polo Fibonacci Alberto D'Onofrio (IEO-Milano) : Immunoterapia dei tumori e competizione tumore-sistema immune: oncologia matematica e applicazioni cliniche ************************************************************************************ _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] Fw: Annuncio di Seminario ISTI: Schildknecht.txt
by Giulia Curciarello 09 Nov '06

09 Nov '06

> > > Istituto di Scienza e Tecnologie dell'Informazione "A. Faedo" > Consiglio Nazionale delle Ricerche > Area della Ricerca di Pisa > > > AVVISO DI SEMINARIO > > Data: Mercoledi' 15 novembre 2006, ore 14.30 > Relatore: Dr. Thomas Schildknecht > Affiliazione: Astronomical Institute, University of Bern > Titolo: Optical Observations of Space Debris in High-Altitude > Orbits > Luogo: ISTI - Aula C34 (Ingresso 19 dell'Area di Ricerca) > Riferimento: Alessandro Rossi e-mail: Alessandro.Rossi(a)isti.cnr.it > ABSTRACT > > > In the framework of its space debris research activities ESA established > an optical survey program to study the space debris environment at high > altitudes, in particular in the geostationary ring and in the > geostationary > transfer orbit region. The Astronomical Institute of the University of > Bern > (AIUB) performs these surveys on behalf of ESA using ESA's 1-meter > Telescope > in Tenerife. We will briefly summarize this program and the main results. > The main part of the presentation will be dedicated to a discussion of the > observation techniques used, including the survey scenarios, the object > detection techniques and the correlation procedures. > > _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] AVVISI SEMINARI
by Giulia Curciarello 09 Nov '06

09 Nov '06

Come da precedente annuncio: Oggi pomeriggio alle 15 e alle 16.30, in aula seminari, si terrano i seminari A. Suciu (Northeastern, Boston) , "Some combinatorial constructions in topology and group theory" e S. Papadima (Accademy of Science, Bucharest) "Cohomology jumping loci and fundamental groups of algebraic varieties" _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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[Settimanale] SEMINARI DI SISTEMI DINAMICI OLOMORFI (e dintorni)
by Giulia Curciarello 09 Nov '06

09 Nov '06

SEMINARI DI SISTEMI DINAMICI OLOMORFI (e dintorni) Mercoledi' 15 novembre ore 14.00 Centro di Ricerca Matematica De Giorgi - Sala Conferenze David Sauzin (IMCCE) "Ergodicity and convergence to a Brownian motion in examples of Arnold ì diffusion." Abstract: In the same line of research as [Marco-Sauzin, ETDS 2004], I construct examples of near-integrable Hamiltonian systems with $N+1/2$ degrees of freedom ($N\ge2$), which are as smooth as possible and as ``unstable'' as possible. They are generated by Hamiltonian functions of the form $\frac{1}{2}(I_12+\cdots+I_N2) + f(\theta,I,t)$ with Gevrey functions $f$ which are $1$-periodic in time and arbitrarily small. The Nekhoroshev theorem [Marco-Sauzin, IHES 2002] forces exponential stability. Still, for these particular $f$, one can find probability measures in the phase space such that the first $N-1$ action variables satisfy a functional central limit theorem: when properly rescaled, they converge in law to a Brownian motion (with an exponentially small coefficient of diffusion, as should be). These probability measures are related to the product of the $2(N-1)$-fold Lebesgue measure by a measure supported on a horseshoe on the last degree of freedom. There is a related invariant measure $m$ for the time-$1$ map, which is $\sigma$-finite but not finite. One can show that, when $N=1$ or $N=2$, the time-$1$ map is $m$-ergodic. For $N\ge3$, $m$-almost orbit is biasymptotic to infinity and the system is not ergodic (but there still exist orbits which are dense in the support of $m$, which is the product of the first $N-1$ degrees of freedom by the horseshoe). _______________________________________________ Settimanale mailing list Settimanale(a)mail.dm.unipi.it https://mail.dm.unipi.it/mailman/listinfo/settimanale

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