Clock synchronization is a very fundamental task in distributed system. It thus makes sense to require an underlying clock synchronization mechanism to be highly fault-tolerant. A self-stabilizing algorithm seeks to attain synchronization once lost; a Byzantine algorithm assumes synchronization is never lost and focuses on containing the influence of the permanent presence of faulty nodes. Ther...

This thesis presents a scheme that achieves self-stabilizing Byzantine digital clock synchronization assuming a “synchronous” system. This synchronous system is established by the assumption of a common external “beat” delivered with a regularity in the order of the network message delay, thus enabling the nodes to execute in lock-step. The system can be subjected to severe transient failures w...

We present a scheme that achieves self-stabilizing Byzantine digital clock synchronization assuming a “synchronous” system. This synchronous system is established by the assumption of a common external “beat” delivered with a regularity in the order of the network message delay, thus enabling the nodes to execute in lock-step. The system can be subjected to severe transient failures with a perm...

The growth of data, the need for scalability and the complexity of models used in modern machine learning calls for distributed implementations. Yet, as of today, distributed machine learning frameworks have largely ignored the possibility of arbitrary (i.e., Byzantine) failures. In this paper, we study the robustness to Byzantine failures at the fundamental level of stochastic gradient descent...

Pease et al. introduced the problem of Byzantine Generals (BGP) to study the effects of Byzantine faults in distributed protocols for reliable broadcast. It is well known that BGP among n players tolerating up to t faults is (efficiently) possible if and only if n > 3t. To overcome this severe limitation, Pease et al. introduced a variant of BGP, Authenticated Byzantine General (ABG). Here play...

We introduce a new visual programming system PrologSpace. The system addresses classic issues of visual interfaces: layout, shape, colour, and iconography; and those of particular concern to visual programming: multiple views (visual abstractions), synchronised views, integration of visual and textual dimensions, visual debugging, cognitive dimensions, and the problems of scale. We brieey descr...

ing out Byzantine Behavior Peter Druschel, Andreas Haeberlen, Petr Kouznetsov Max Planck Institute for Software Systems MPI-SWS, Stuhlsatzenhausweg 85, 66123 Saarbrücken, Germany {druschel,ahae,pkouznet}@mpi-sws.mpg.de Abstract. Many distributed systems are designed to tolerate the presence of Byzantine failures: an individual process may arbitrarily deviate Many distributed systems are designe...

Consider a synchronous point-to-point network of n nodes connected by directed links, wherein each node has a binary input. This paper proves a tight necessary and sufficient condition for achieving Byzantine consensus among these nodes in the presence of up to f Byzantine faults. We derive two forms of the necessary condition. We provide a constructive proof of sufficiency by presenting a Byza...

To circumvent the FLP impossibility result in a deterministic way several protocols have been proposed on top of an asynchronous distributed system enriched with additional assumptions. In the context of Byzantine failures for systems where at most t processes may exhibit a Byzantine behavior, two approaches have been investigated to solve the consensus problem.The first, relies on the addition...

We consider a system with n processes where some of them can show a byzantine behavior. A byzantine process can deviate arbitrarily from the protocol, e.g., dropping messages, changing the content of a message (different recipients may receive different content of the same broadcast message), delivering messages not sent by any process or creating fake messages. This paper introduces a new broa...