Janna Burman

On utilizing speed in networks of mobile agents

Population protocols are a model presented recently for networks with a very large, possibly unknown number of mobile agents having small memory. This model has certain advantages over alternative models (such as DTN) for such networks. However, it was shown that the computational power of this model is limited to semi-linear predicates only. Hence, various extensions were suggested. We present a model that enhances the original model of population protocols by introducing a (weak) notion of speed of the agents. This enhancement allows us to design fast converging protocols with only weak requirements (for example, suppose that there are different types of agents, say agents attached to sick animals and to healthy animals, two meeting agents just need to be able to estimate which of them is faster, e.g., using their types, but not to actually know the speeds of their types). Then, using the new model, we study the gathering problem, in which there is an unknown number of anonymous agents that have values they should deliver to a base station (without replications). We develop efficient protocols step by step searching for an optimal solution and adapting to the size of the available memory. The protocols are simple, though their analysis is somewhat involved. We also present a more involved result - a lower bound on the length of the worst execution for any protocol. Our proofs introduce several techniques that may prove useful also in future studies of time in population protocols.

Asynchronous and fully self-stabilizing time-adaptive majority consensus

We study the scenario where a batch of transient faults hits an asynchronous distributed system by corrupting the state of some f nodes. We concentrate on the basic majority consensus problem, where nodes are required to agree on a common output value which is the input value of the majority of them. We give a fully self-stabilizing adaptive algorithm, i.e., the output value stabilizes in O(f) time at all nodes, for any unknown f. Moreover, a state stabilization occurs in time proportional to the (unknown) diameter of the network. Both upper bounds match known lower bounds to within a constant factor. Previous results (stated for a slightly less general problem called “persistent bit”) assumed the synchronous network model, and that f

Self-stabilizing Leader Election in Population Protocols over Arbitrary Communication Graphs

This paper considers the fundamental problem of self-stabilizing leader election (

Self-stabilizing synchronization in mobile sensor networks with covering

\mathcal{SSLE}

Brief announcement: non-self-stabilizing and self-stabilizing gathering in networks of mobile agents--the notion of speed

) in the model of population protocols. In this model, an unknown number of asynchronous, anonymous and finite state mobile agents interact in pairs over a given communication graph.

Power-Aware Population Protocols

\mathcal{SSLE}

The Weakest Oracle for Symmetric Consensus in Population Protocols

has been shown to be impossible in the original model. This impossibility can been circumvented by a modular technique augmenting the system with an oracle - an external module abstracting the added assumption about the system. Fischer and Jiang have proposed solutions to

Time optimal asynchronous self-stabilizing spanning tree

\mathcal{SSLE}

Making Population Protocols Self-stabilizing

, for complete communication graphs and rings, using an oracle Ω?, called the eventual leader detector. In this work, we present a solution for arbitrary graphs, using a composition of two copies of Ω?. We also prove that the difficulty comes from the requirement of self-stabilization, by giving a solution without oracle for arbitrary graphs, when an uniform initialization is allowed. Finally, we prove that there is no self-stabilizing implementation of Ω? using

Time and Space Optimal Counting in Population Protocols.

\mathcal{SSLE}