LIRa Session: Hans van Ditmarsch

Speaker: Hans van Ditmarsch

Date and Time: Thursday, April 1st 2021, 16:30-18:00, Amsterdam time.

Venue: online.

Title: Everyone Knows that Everyone Knows: Gossip Protocols for Super Experts.

Abstract. A gossip protocol is a procedure for sharing secrets in a network. The basic action in a gossip protocol is a telephone call wherein the calling agents exchange all the secrets they know. An agent who knows all secrets is an expert. The usual termination condition is that all agents are experts.
Instead, we explore protocols wherein the termination condition is that all agents know that all agents are experts. We call such agents super experts. Additionally, we model that agents who are super experts do not make and do not answer calls. Such agents are called engaged agents. We also model that such gossip protocols are common knowledge among the agents. We investigate conditions under which protocols terminate, both in the synchronous case, where there is a global clock, and in the asynchronous case, where there is not. We show that a commonly known protocol with engaged agents may terminate faster than the same protocol without engaged agents.

This is a joint work Malvin Gattinger and Rahim Ramezanian, available at The slides of the talk can be downloaded here.