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MAK Crypto Seminar

By: Giulia Traverso (TU Darmstadt, Germany) Title: Dynamic and Verifiable Hierarchical Secret Sharing

By: Giulia Traverso (TU Darmstadt, Germany) Title: Dynamic and Verifiable Hierarchical Secret Sharing

Quan
18/03/2016 des de/d' 12:00" (Europe/Madrid / UTC100)
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Campus Nord UPC, Building C3, Room 204a (2nd floor)
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By: Giulia Traverso (TU Darmstadt, Germany)

Title: Dynamic and Verifiable Hierarchical Secret Sharing

Abstract

In this work we provide a framework for dynamic secret sharing and present the first dynamic and verifiable hierarchical secret sharing scheme based on Birkhoff interpolation. Since the scheme is dynamic it allows, without reconstructing the message distributed, to add and remove shareholders, to renew shares, and to modify the conditions for accessing the message. Furthermore, each shareholder can verify its share received during these algorithms protecting itself against malicious dealers and shareholders. While these algorithms were already available for classical Lagrange interpolation based secret sharing, corresponding techniques for Birkhoff interpolation based schemes were missing. Note that Birkhoff interpolation is currently the only technique available that allows to construct hierarchical secret sharing schemes that are efficient and allow to provide shares of equal size for all shareholder in the hierarchy. Thus, our scheme is an important contribution to hierarchical secret sharing and to other techniques using this primitive, such as social secret sharing based cloud storage.

Computational geometry seminar: Carlos Seara

Quan
17/03/2016 de 13:15 a 14:15 (Europe/Madrid / UTC100)
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hursday, March 17, 2016, 13:15-14:15 (15 minutes delayed with respect to the usual schedule) Room S215 Omega Building, Campus Nord UPC (equiv.: Room 215 Floor -2)

Title: Covering points with rotating polygons
Speaker: Carlos Seara (Universitat Politècnica de Catalunya)

Abstract

 We study the problem of rotating a simple polygon to contain the maximum number of elements from a given point set. We consider variations of this problem where the rotation center is a given point or lies on a line segment, a line, or a polygonal chain. This is a joint work with Carlos Alegría, David Orden, Leonidas Palios, and Jorge Urrutia.

Activities are regularly announced at
http://www-ma2.upc.edu/dccg/upc-seminar-on-computational-geometry/http://www-ma2.upc.edu/dccg/upc-seminar-on-computational-geometry/

CRM Colloquium

Quan
17/03/2016 des de/d' 12:00" (Europe/Madrid / UTC100)
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Auditorium at the Centre de Recerca Matemàtica
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CRM Colloquium to be held next Thursady, March 17, 2016.
Place: Auditorium at the Centre de Recerca Matemàtica
Time: 12 pm
Title: Could the subprime crisis have been foreseen?
Talk delivered by Dr. Jordi Molins.

You can find the information on the abstract and talk here
http://www.crm.cat/en/Activities/Curs_2015-2016/Documents/Poster%20CRM%20Colloquium.pdf

LIMDA Joint Seminar Announcement

Christoph Spiegel (Freie Universität Berlin): Threshold functions for systems of equations in random sets

Christoph Spiegel (Freie Universität Berlin): Threshold functions for systems of equations in random sets

Quan
17/03/2016 des de/d' 12:00" (Europe/Madrid / UTC100)
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Room C3-005, Campus Nord UPC
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Abstract

We present a unified framework to deal with threshold functions for the existence of solutions to systems of linear equations in random sets. This covers the study of several fundamental combinatorial families such as k-arithmetic progressions, k-sum-free sets, B_h(g)- sequences and Hilbert cubes of dimension k.

We show that there exists a threshold function for the property "A^m contains a non-trivial solution of Mx=0" where A is a random set. This threshold function depends on a parameter maximized over all subsystems, a notion previously introduced by Rödl and Rucinski. The talk will contain a formal definition of trivial solutions for any combinatorial structure, extending a previous definition by Ruzsa.

Joint work with Juanjo Rué Perna and Ana Zumalacárregui.

Seminari de Sistemes Dinàmics UB-UPC: David Chillingworth

Quan
16/03/2016 des de/d' 16:00" (Europe/Madrid / UTC100)
On
Aula T2, Facultat de Matemàtiques, UB
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Seminari de Sistemes Dinàmics UB-UPC: David Chillingworth. Geometry of grazing and chatter for a simple impact oscillator


Dimecres 16 de març de 2016 a les 16h, Aula T2, Facultat de Matemàtiques, UB
Més informació a http://www.maia.ub.es/ssd.shtml

BARCCSYN 2016

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16/03/2016 a 17/03/2016 (Europe/Madrid / UTC100)
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We would like to inform that we are organizing the fifth session of the Barcelona Computational, Cognitive and Systems Neuroscience (BARCCSYN 2016), which will be held at the Institut d’Estudis Catalans (Barcelona), on June 16 and 17, 2016.

BARCCSYN is about bringing together researchers from computational, systems and cognitive neuroscience. Our goal is to provide a forum for lively discussion and promote active collaboration between Barcelona-based research groups, especially between theorists and experimentalists.

Please note the following deadlines:

  • May 15: Deadline to present a poster or short communication.  
  • June 5: Deadline to register (or until all available seats are filled). 

Registration fee: 60 € (includes: documentation package, lunch tickets, and coffee breaks) 

You can find more information and register at:http://www.crm.cat/en/Activities/Curs_2015-2016/Pages/BARCCSYN-2016.aspx 
We hope that this information is of your interest and we hope to see you soon in Barcelona, 

Organisers

  • Gemma Huguet (Universitat Politècnica de Catalunya), 
  • Roser Nadal (Universitat Autònoma de Barcelona), 
  • Vicky Puig (Institut Hospital del Mar d’Investigacions Mèdiques), 
  • Alex Roxin (Centre de Recerca Matemàtica) 

GREDPA: Existence and regularity theories of mean curvature flow

A càrrec de Yoshihiro Tonegawa (Tokyo Institute of Technology)

A càrrec de Yoshihiro Tonegawa (Tokyo Institute of Technology)

Quan
10/03/2016 des de/d' 15:00" (Europe/Madrid / UTC100)
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Aula S01, FME-UPC
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Seminari de Sistemes dinàmics UB-UPC: Singularities in planar piecewise smooth systems

John Hogan (University of Bristol): Singularities in planar piecewise smooth systems.

John Hogan (University of Bristol): Singularities in planar piecewise smooth systems.

Quan
09/03/2016 des de/d' 16:00" (Europe/Madrid / UTC100)
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Aula S01, FME, UPC
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John Hogan (University of Bristol): Singularities in planar piecewise smooth systems.

Més informació a http://www.maia.ub.es/ssd.shtml

Data d'inici

09/03/2016 16:00

Lloc

Aula S01, FME, UPC

Lectura tesi doctoral: Bin Li

Quan
08/03/2016 des de/d' 17:00" (Europe/Madrid / UTC100)
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Sala 002 Modul C1, Campus Nord
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s informem de la propera lectura de tesi doctoral:
Títol: The variational approach to brittle fracture in materials with anisotropic surface energy and in thin sheets
Doctorand: Bin Li

Directors: Marino Arroyo i Irene Arias 

Dia : 08-03-2016
 Hora : 17:00
Lloc : Sala 002 Modul C1, Campus Nord

http://doctorat.upc.edu/tesi/llistats-de-tesis/tesis-autoritzades-per-lectura

Seminari Teoria de Grups: Normal subgroups of groups of piecewise projective homeomorphisms of R

Quan
08/03/2016 des de/d' 15:00" (Europe/Madrid / UTC100)
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FME-UPC room 101
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Date: Tuesday March 8th, 2016, 15h
Place: FME-UPC room 101
Title: "Normal subgroups of groups of piecewise projective homeomorphisms of R"
Speaker: Pep Burillo (UPC)

Abstract: In this talk we will explore subgroups of the Lodha-Moore groups G and G_0\. The group G_0 presents many similarities with Thompson's group F, and we will prove that, as it happens with F, its commutator subgroup is simple. This fact has some consequences, namely, that every proper quotient is abelian, or that every finite-index subgroup is normal. In the case of G, is its second commutator subgroup the one which is simple. We will extend these results to the whole family of groups H(A) introduced by Monod in 2012\. This is joint work with Yash Lodha and Lawrence Reeves.