LogiCIC/LIRa double session: Jeremy Seligman and Thomas Ågotnes.

On Tuesday, September 9, we will have a LogiCIC/LIRa seminar with 2 talks by Jeremy Seligman and Thomas Ågotnes.

Everyone is cordially invited!


Venue: Science Park 107, Room F1.15

Date and Time: Tuesday, September 9, 2014, 12:00-14:00 :

12:00-13:00: Jeremy Seligman (University of Auckland)
Title: Exploiting and maintaining network Ignorance
Abstract: Suppose you want to send a message to someone in your extended social network secretly i.e. without others coming to know it. Can this be done and if so how? Addressing this question raises many others. What do you know about the structure of the network and the knowledge of other agents? What kind of message can you send? And what do you really mean by “secretly”? Is it acceptable that other agents get to know some but not all of your message? What sense can be given to their knowing none of it? We offer a formalisation of perhaps the simplest answers to these questions, which exhibits interesting complexity nonetheless, in particular concerning the concepts of potential social knowledge. (Joint work with Thomas Agotnes and Mostafa Raziebrahimsaraei.)

13:00-14:00: Thomas Ågotnes (University of Bergen)
Title: From Distributed to Common Knowledge
Abstract: The topic of the talk is standard notions of group knowledge and belief, with a focus on distributed knowledge. First, I will discuss a natural range of group belief concepts with distributed and general (“everybody-believes”) as the two extreme endpoints and with many intermediate concepts in between. Distributed knowledge is sometimes described as what the members of the group would know of they “pool their knowledge together”. This is inaccurate at best: for example, it is consistent that a group has distributed knowledge of a Moore sentence involving one of the members of the group (a sentence which cannot be known by that member, no matter how much “pooling” has taken place). In the second part of the talk, based on joint work with Yi Wáng, I discuss a new group modality that actually captures what is true after the group have fully shared their information with each other — after their distributed knowledge has been resolved. A key question is: when does distributed knowledge become common knowledge?