The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We present the first optimally resilient, bounded, wait-free implementation of a distributed atomic register, tolerating Byzantine readers and (up to one-third of) Byzantine servers, without the use of unproven cryptographic primitives or requiring communication among servers. Unlike previous (non-optimal) solutions, the sizes of messages sent to writers depend only on the actual number of active...
We describe and analyze a 3-state one-way population protocol for approximate majority in the model in which pairs of agents are drawn uniformly at random to interact. Given an initial configuration of x’s, y’s and blanks that contains at least one non-blank, the goal is for the agents to reach consensus on one of the values x or y. Additionally, the value chosen should be the majority non-blank initial...
We consider the problem of designing scalable and robust information systems based on multiple servers that can survive even massive denial-of-service (DoS) attacks. More precisely, we are focusing on designing a scalable distributed hash table (DHT) that is robust against so-called past insider attacks. In a past insider attack, an adversary knows everything about the system up to some time point...
We present a model of a mobile ad-hoc network in which nodes can move arbitrarily on the plane with some bounded speed. We show that without any assumption on some topological stability, it is impossible to solve the geocast problem despite connectivity and no matter how slowly the nodes move. Even if each node maintains a stable connection with each of its neighbours for some period of time, it is...
Distributed computing must adapt its techniques to networks of mobile agents. Indeed, we are facing new problems like the small size of memory and the lack of computational power. In this paper, we extend the results of Angluin et al (see [4,3,2,1]) by finding self-stabilizing algorithms to count the number of agents in the network. We focus on two different models of communication, with a fixed base...
We introduce the problem of load-distance balancing in assigning users of a delay-sensitive networked application to servers. We model the service delay experienced by a user as a sum of a network-incurred delay, which depends on its network distance from the server, and a server-incurred delay, stemming from the load on the server. The problem is to minimize the maximum service delay among all users...
This paper presents an improved and time-optimal self-stabilizing algorithm for a major task in distributed computing- a rooted spanning tree construction. Our solution is decentralized (“truly distributed”), uses a bounded memory and is not based on the assumption that either n (the number of nodes), or diam (the actual diameter of the network), or an existence of cycles in the network are known...
A group of identical mobile agents moving asynchronously among the nodes of an anonymous network have to gather together in a single node of the graph. This problem known as the (asynchronous anonymous multi-agent) rendezvous problem has been studied extensively but only for networks that are safe or fault-free. In this paper, we consider the case when some of the edges in the network are dangerous...
In this paper, we propose the partition approach and define several new classes of partitioned failure detectors weaker than existing failure detectors for the k-set agreement problem in both the shared-memory model and the message-passing model. In the shared-memory model with n + 1 processes, for any 2 ≤ k ≤ n, we first propose a partitioned failure detector ΠΩk...
Distributed storage algorithms implement the abstraction of a shared register over distributed base objects. We study a specific class of storage algorithms, which we call amnesic: these have the pragmatic property that old values written in the implemented register might be eventually forgotten, i.e., they are not permanently kept in the storage and might be overwritten in the base objects by more...
We give a distributed approximation algorithm for the vertex-packing problem in unit-disk graphs. Given a graph H, the algorithm finds in a unit-disk graph G a collection of pairwise disjoint copies of H of size which is approximately equal to the packing number of H in G. The algorithm is deterministic and runs in a poly-logarithmic number of rounds in the message passing model.
This paper studies the impact of omission failures on asynchronous distributed systems with crash-stop failures. We provide two different transformations for algorithms, failure detectors, and problem specifications, one of which is weakest failure detector preserving. We prove that our transformation of failure detector Ω [1] is the weakest failure detector for consensus in environments with crash-stop...
The paper presents a deterministic distributed algorithm that given an n node unweighted graph constructs an O(n3/2) edge 3-spanner for it in O(logn) time. This algorithm is then extended into a deterministic algorithm for computing an O(kn1 + 1/k) edge O(k)-spanner in 2O(k)logk − 1n time for every integer parameter...
Consider a distributed network of n nodes that is connected to a global source of “beats”. All nodes receive the “beats” simultaneously, and operate in lock-step. A scheme that produces a “pulse” every Cycle beats is shown. That is, the nodes agree on “special beats”, which are spaced Cycle beats apart. Given such a scheme, a clock synchronization algorithm is built. The “pulsing” scheme is self-stabilized...
We study oblivious deterministic gossip algorithms for multi-channel radio networks with a malicious adversary. In a multi-channel network, each of the n processes in the system must choose, in each round, one of the c channels of the system on which to participate. Assuming the adversary can disrupt one channel per round, preventing communication on that channel, we establish a tight bound of ...
The timestamp problem captures a fundamental aspect of asynchronous distributed computing. It allows processes to label events throughout the system with timestamps that provide information about the real-time ordering of those events. We consider the space complexity of wait-free implementations of timestamps from shared read-write registers in a system of n processes. We prove an $\Omega(\sqrt{n})$...
We study adaptive routing algorithms in a round-based model. Suppose we are given a network equipped with load-dependent latency functions on the edges and a set of commodities each of which is defined by a collection of paths (represented by a DAG) and a flow rate. Each commodity is controlled by an agent which aims at balancing its traffic among its paths such that all used paths have the same latency...
The paper considers broadcasting protocols in radio networks with known topology that are efficient in both time and energy. The radio network is modelled as an undirected graph G = (V,E) where |V| = n. It is assumed that during execution of the communication task every node in V is allowed to transmit at most once. Under this assumption it is shown that any radio broadcast protocol requires $D+\Omega(\sqrt{n-D})$...
Communication in networks suffers if a link fails. When the links are edges of a tree that has been chosen from an underlying graph of all possible links, a broken link even disconnects the network. Most often, the link is restored rapidly. A good policy to deal with this sort of transient link failures is swap rerouting, where the temporarily broken link is replaced by a single swap link from the...
Many recommend planning for the worst and hoping for the best. In this paper we devise efficient indulgent consensus algorithms that can tolerate crash failures and arbitrarily long periods of asynchrony, and yet perform (asymptotically) optimally in well-behaved, synchronous executions with few failures. We present two such algorithms: In synchronous executions, the first has optimal message complexity...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.