Colloquia and Seminars

To join the email distribution list of the cs colloquia, please visit the list subscription page.

Upcoming Colloquia & Seminars

  • ceClub: Crowdsourcing a Meeting of Minds

    Speaker:
    Michael Bernstein (CS, Stanford University)
    Date:
    Monday, 22.12.2014, 13:30
    Place:
    Room 337-8 Taub Bld.

    Crowdsourcing is an increasingly powerful method for combining amateurs' efforts to recreate an expert's abilities. However, across domains from design to engineering to art, few goals are truly the effort of just one person — even one expert. If we can now crowdsource simple tasks such as image labeling, how might we coordinate many peoples' abilities toward far more complex and interdependent goals? In this talk, I present computational systems for gathering and guiding crowds of experts --- including professional programmers, designers, singers and artists. The resulting collectives tackle problems modularly and at scale, dynamically grow and shrink depending on task demands, and combine into larger organizations. I'll demonstrate how these expert crowds, which we call Flash Teams, can pursue goals such as designing new user experiences overnight and producing animated shorts in two days.

    Bio:
    Michael Bernstein is an Assistant Professor of Computer Science at Stanford University, where he co-directs the Human-Computer Interaction group and is a Robert N. Noyce Family Faculty Scholar. His research in human-computer interaction focuses on the design of crowdsourcing and social computing systems. This work has received Best Paper awards and nominations at premier venues in human-computer interaction and social computing (ACM UIST, ACM CHI, ACM CSCW, AAAI ISWSM). Michael has been recognized with the NSF CAREER award, as well as the George M. Sprowls Award for best doctoral thesis in Computer Science at MIT. He holds Ph.D. and M.S. degrees in Computer Science from MIT, and a B.S. in Symbolic Systems from Stanford University.

    Light refreshments will be served.

  • ceClub:Majority is not Enough: Bitcoin Mining is Vulnerable

    Speaker:
    Ittay Eyal (Cornell University)
    Date:
    Wednesday, 24.12.2014, 11:30
    Place:
    EE Meyer Building 1007

    The Bitcoin cryptocurrency records its transactions in a public log called the blockchain. Its security rests critically on the distributed protocol that maintains the blockchain, run by participants called miners. Conventional wisdom had asserted that the protocol was incentive-compatible and secure against colluding minority groups, i.e., it incentivized miners to follow the protocol as prescribed.

    I will show that the Bitcoin protocol is not incentive-compatible by presenting an attack with which colluding miners obtain a revenue larger than their fair share. This attack can have significant consequences for Bitcoin: Rational miners would prefer to join the selfish miners, and the colluding group would increase in size until it became a majority. At this point, the Bitcoin system ceases to be a decentralized currency.

    Selfish mining may be feasible for any group size of colluding miners. However, a practical modification to the Bitcoin protocol can protect against selfish mining pools that command less than 1/4 of the resources. This threshold is lower than the wrongly assumed 1/2 bound, but better than the current reality where a group of any size can compromise the system.

    Bio:
    Ittay is a post-doctoral associate in the Department of Computer Science in Cornell University. He completed his PhD in the Technion in 2012 under the supervision of Prof. Idit Keidar and Prof. Raphi Rom. Ittay's main research interests are the security and scalability of the Blockchain protocol (on which Bitcoin runs) and consistent distributed storage algorithms.

  • Theory Seminar:Inapproximability of Nash Equilibrium

    Speaker:
    Aviad Rubinstein (UC Berkeley)
    Date:
    Wednesday, 24.12.2014, 12:30
    Place:
    Taub 401

    We prove that finding an epsilon-approximate Nash equilibrium is PPAD-complete for constant epsilon and a particularly simple class of games: polymatrix, degree 3 graphical games, in which each player has only two actions. As corollaries, we also prove similar inapproximability results for Bayesian Nash equilibrium in a two-player incomplete information game with a constant number of actions, for market equilibrium in a non-monotone market, for the generalized circuit problem defined in [Chen, Deng, Teng, 2009], and for approximate competitive equilibrium from equal incomes with indivisible goods.

  • Lessons Learned from and for Requirements Engineering and Building Construction: A Case Study of Requirements Engineering for a Synagogue Kitchen with Use Cases and Scenarios

    Speaker:
    Daniel M. Berry - Colloquium Lecture -
    Date:
    Wednesday, 24.12.2014, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20141224_14_30_Berry.html
  • An Algorithmic Approach for Analyzing Social Phenomena

    Speaker:
    Sigal Oren - CS-Lecture
    Date:
    Sunday, 28.12.2014, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20141228_14_30_Oren.html
  • Machine-Learning the Hidden Universal Semantics of Natural Languages

    Speaker:
    Omri Abend - CS-Lecture -
    Date:
    Monday, 29.12.2014, 14:30
    Place:
    Room 401 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20141229_14_30_Abend.html
  • How to reach unreachable computers

    Speaker:
    Prof. Adi Shamir - Colloquium Lecture -
    Date:
    Tuesday, 30.12.2014, 14:30
    Place:
    Room Auditorium 1 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20141230_14_30_Shamir.html
  • Fast matrix multiplication: Limitations of the Coppersmith-Winograd approach

    Speaker:
    Yuval Filmus - CS-Lecture -
    Date:
    Wednesday, 31.12.2014, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20141231_14_30_Filmus.html
  • Regression Testing of Security Updates Using Deterministic Record/Replay Infrastructure

    Speaker:
    Ilia Kravets, M.Sc. Thesis Seminar
    Date:
    Wednesday, 31.12.2014, 15:30
    Place:
    Taub 601
    Advisor:
    Dan Tsafrir

    After a software product is shipped, it typically goes into a maintenance phase whereby related software updates are made available form time to time. Such updates should in principle have a positive effect (e.g. fixing bugs), but in reality the users often favor stability over the possible improvements brought by updates, worrying about the possibility of updates somehow adversely affecting their systems. However, leaving security vulnerabilities fixes unapplied might lead to highly undesirable consequences, such as denial of service or system compromise. To lower the risk of an update a staging environment can be created, containing the system replica to which an update is first applied. Then a regression testing is performed, ensuring the updated system still behaves correctly. This testing is usually a laborious manual process, limiting a frequency at which it can be performed. Deterministic Record/Replay is an ability of the system to precisely reproduce its previous execution. Such systems usually employ a combination of state snapshots with an event log, populated during record phase and used to guide the execution of replay phase. In this work we study security updates of a real life systems and applicability of deterministic record/replay techniques for automating regression testing of such updates.

  • Aspects of Submodular Maximization Subject to a Matroid Constraint

    Speaker:
    Moran Feldman - CS-Lecture
    Date:
    Thursday, 1.1.2015, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150101_14_30_Feldman.html
  • Exponential Separation of Information and Communication

    Speaker:
    Gillat Kol- CS-Lecture -
    Date:
    Monday, 5.1.2015, 14:30
    Place:
    Room Class 4, Floor 1, Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150105_14_30_Kol.html
  • Uncertainty, Strategy, and Bounded Rationality

    Speaker:
    Reshef Meir - CS-Lecture
    Date:
    Tuesday, 6.1.2015, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150106_14_30_Reshef.html
  • Parallel Repetition From Fortification

    Speaker:
    Dana Moshkovitz - Colloquium Lecture -
    Date:
    Thursday, 8.1.2015, 12:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150108_12_30_Moshkovitz.html
  • When Exactly Do Quantum Computers Provide a Speedup?

    Speaker:
    Scott Aaronson - Colloquium Lecture
    Date:
    Thursday, 8.1.2015, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150108_14_30_Aaronson.html
  • CGGC Seminar: Voronoi diagram of line segments and convex polygons with convex polygon-offset distance functions

    Speaker:
    Minati De (CS, Technion)
    Date:
    Sunday, 11.1.2015, 14:30
    Place:
    Taub 401

    Voronoi diagrams are one of the most powerful data structures in computational geometry. Barequet, Dickerson, and Goodrich [D&CG 2001] introduced the notion of polygon-offset distance function for points. The polygon-offset distance function is more natural than scaling and is useful to model many problems which arise in manufacturing tolerances. Using this distance function, they studied the nearest- and farthest-site Voronoi diagrams of point sites in the plane. In this talk, I will generalize the polygon-offset distance function to convex polygonal objects and present the combinatorial complexity of the nearest - and farthest-site Voronoi diagrams of line segments and convex polygons.

  • Coding For Interactive Communication

    Speaker:
    Klim Efremenko - CS-Lecture -
    Date:
    Monday, 12.1.2015, 14:30
    Place:
    Room 337-8 Taub Bld.
    Link:
    http://www.cs.technion.ac.il/~colloq/20150112_14_30_Efremenko.html