On *Thursday 23* at *2pm (CEST)*, Prof. Thomas Ågotnes, from Bergen
University, will deliver a talk on:
*The Russian Cards Problem: Crossing Hands*
If interested, you're warmly invited to attend in person in *Room 2AB40*
- Torre di Archimede.
===
*Abstract*:
The Russian Cards Problem (RCP), originally introduced in the Moscow
Mathematical Olympiad in 2000, is an example of a problem of an
unconditionally secure protocol where the sender and receiver are able
to transmit secret information safely over a completely non-secure
channel with out any prior exchange of keys or any other information,
without the secret being learned by a third party with access to the
channel. Analysis of the RCP turns out to involve subtle implicit
assumptions about agents knowledge and their reasoning about nested
higher-order knowledge (knowledge about others knowledge), and modal
epistemic logic and in particular public announcement logic, have turned
out to be very useful in this study. In turn the RCP has informed the
developments of these logics. In this talk I will introduce the RCP and
epistemic and public announcement logic, and solutions to the RCP. I
will in particular focus on a new result. It has been a long standing
open problem whether or not there exist protocols of length strictly
greater than two. We resently settled this problem, answering the
question in the affirmative, by presenting a new solution to the
original RCP that involves more than two steps. It starts with an
initial announcement with so-called crossing hands, after which it is
not common knowledge that the protocol can terminate in one more step.
===
*Short Bio*
Thomas Ågotnes is a Professor of Information Science and head of the
Logic and AI research group at the Department of Information Science and
Media Studies, University of Bergen, Norway. He is also a visiting
Professor at the Centre for the study of Logic and Intelligence at
Southwest University, China. His main research interests include formal
knowledge representation and reasoning about different types of
interaction, in particular using modal logic, often combined with other
mathematical models of interaction for example from game theory, with
applications in the fields of artificial intelligence and multi-agent
systems. He has published extensively in these fields. He has been
awarded the Changjiang (Yangtze river) Scholar award by the Chinese
government, and best paper awards at conferences such as AAMAS and CLAR.