Combining Tentative and Definite Executions for Very Fast Dependable Parallel Computing (Extended Abstract)

We present a general and efficient strategy for computing robustly on unreliable parallel machines. The model of a parallel machine that we use is a CRCW PRAM with dynamic resource fluctuations: processors can fail during the computation, and may possibly be restored later. We first introduce the notions of definite and tentative algorithms for executing a single parallel step of an ideal parallel machine on the unreliable machine. A definite algorithm is one that guarantees a correct execution of