Tomas Rokicki

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Most standard cluster interconnect technologies are flexible with respect to network topology. This has spawned a substantial amount of research on topology-agnostic routing algorithms, which make no assumption about the network structure, thus providing the flexibility needed to route on irregular networks. Actually, such an irregularity should be often(More)
We give an expository account of our computational proof that every position of Rubik’s Cube can be solved in 20 moves or less, where a move is defined as any twist of any face. The roughly 4.3 × 1019 positions are partitioned into about two billion cosets of a specially chosen subgroup, and the count of cosets required to be treated is reduced by(More)
This paper presents an approach to using Stochastic Petri nets to model large-scale concurrent systems, in our case, a scalable computer interconnect. We show how Stochastic Petri net models can exploit the symmetry of the system to construct a tractable, but approximate, analytic model, and that they can yield results very close to those of a detailed(More)
To be able to model SoS, the whole diversity of their components and structures is represented as Communicating Structures, uniform and systematic compositions of a small number of basic concepts that describe communication, data traffic, and data placement inside SoS. SoS are represented as hierarchical networks of nodes. Each node has memory that may(More)
How many moves does it take to solve Rubik’s Cube? Positions are known that require 20 moves, and it has already been shown that there are no positions that require 27 or more moves; this is a surprisingly large gap. This paper describes a program that is able to find solutions of length 20 or less at a rate of more than 16 million positions a second. We(More)
This paper presents a new formalism and a new algorithm for verifying timed circuits. The formalism, called orbital nets, allows hierarchical verification based on a behavioral semantics of timed trace theory. We present improvements to a geometric timing algorithm that take advantage of concurrency by using partial orders to reduce the time and space(More)
ÐCut-through switching promises low latency delivery and has been used in new generation switches, especially in high speed networks demanding low communication latency. The interconnection of cut-through switches provides an excellent network platform for high speed local area networks (LANs). For cost and performance reasons, irregular topologies should(More)
Clusters of workstations (COWs) are becoming increasingly popular as a cost-effective alternative to parallel computers. In these systems, processors are connected using irregular topologies, providing the wiring flexibility, scalability, and incremental expansion capability required in this environment. Myrinet is one of the most popular interconnection(More)