Weekly research seminar

2017-11-09, 10:15, 4790

Tomasz Wąs (Instytut Informatyki, Uniwersytet Warszawski)

**An Axiomatization of the Eigenvector and Katz Centralities**Feedback centralities are one of the key classes of centrality measures. They assess the importance of a vertex recursively, based on the importance of its neighbours. Feedback centralities includes the Eigenvector Centrality, as well as its variants, such as the Katz Centrality or the PageRank, and...

2017-10-26, 10:15, 4790

Krzysztof R. Apt (Instytut Informatyki, Uniwersytet Warszawski)

**Self-Stabilization Through the Lens of Game Theory**In 1974 E.W. Dijkstra introduced the seminal concept of self-stabilization that turned out to be one of the main approaches to fault-tolerant computing. We show here how his three solutions can be formalized and reasoned about using the concepts of game theory. We also determine the precise number o...

2017-10-12, 10:15, 4790

Leonie Baumann (University of Cambridge)

**Identifying the best agent in a network**This paper develops a mechanism for a principal to assign a prize to the most valuable agent from a set of heterogeneously valued agents in a network. The principal does not know the value of any agent. Agents are competing for the prize and they have a "knowledge network": If two agents are linked,...

2017-10-05, 10:15, 4790

Tomasz Janus (Instytut Informatyki UW)

**On Strong Equilibria and Improvement Dynamics in Network Creation Games**We study strong equilibria in network creation games. These form a classical and well-studied class of games where a set of players form a network by buying edges to their neighbors at a cost of a fixed parameter a. The cost of a player is defined to be the cost of the bought edges plus the sum of d...

2017-06-22, 10:15, 1780

Krzysztof Puchta (Instytut Informatyki, UW)

**A cooperative solution for the three-nation problem of exploitation of the southern bluefin tuna**W trakcie seminarium zaprezentowany zostanie artykuł "A Cooperative Solution for the Three-Nation Problem of Exploitation of the Southern Bluefin Tuna" autorstwa J. Krawczyka i B. Tolwinskiego W pracy: 1.) Rozwiązano problem gry kooperacyjnej. Do dalszych badań zostawiono: 2.) Z...

2017-05-18, 10:15, 1780

Jadwiga Sosnowska (Instytut Informatyki, UW)

**Attachment Centrality for Weighted Graphs**Measuring how central nodes are in terms of connecting a network has recently received increasing attention in the literature and a few dedicated centrality measures have been proposed. One of them is the Attachment Centrality that is the only one that satisfies certain natural axioms desirable for ...

2017-05-11, 10:15, 1780

Oskar Skibski (Instytut Informatyki, UW)

**Axiomatic Characterization of Distance-based Centralities**I will present our initial results concerning the characterization of the distance-based centralities. First, we characterize distance based centralities using Sabidussi's operations of adding and moving edges. Then, by adding one axiom we obtain a natural class of additive distance-based centraliti...

2017-04-20, 10:15, 1780

Tomasz Michalak (Instytut Informatyki, UW)

**Strategic Social Network Analysis**How can individuals and communities protect their privacy against graph-theoretic network analysis tools? How do criminals or terrorists organizations evade detection by such tools? Under which conditions can these tools be made strategy proof? These fundamental questions have attracted little atte...

2017-04-06, 10:15, 1780

Marcin Waniek (Instytut Informatyki, UW)

**On the Construction of Covert Networks**Centrality measures are widely used to identify leaders of covert networks. We study how a group of such leaders can avoid being detected. In more detail, we study the hardness of modifying the network in order to decrease the leaders' ranking positions according to three fundamental centrality meas...

2017-03-30, 10:15, 1780

Marcin Dziubiński (Instytut Informatyki, UW)

**Spectrum of equilibria in Colonel Blotto game**We study Nash equilibria of a symmetric Colonel Blotto game. In this game two players, with N≥1 units of resources each, distribute their resources simultaneously across K≥2 battlefields. We introduce a characteristic of equilibria in this game called spectrum which stands for the fraction of ba...