Robert E. Shostak

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can be used in i m p l e m e n t i n g a re l iab le c o m p u t e r sys tem. W e imag ine t h a t severa l d iv is ions of the B y z a n t i n e a r m y are c a m p e d outs ide a n e n e m y city, each d iv is ion c o m m a n d e d by i ts ow n general . T h e genera l s can c o m m u n i c a t e wi th one a n o t h e r on ly by messenger . Af te r obse(More)
The problem addressed here concerns a set of isolated processors, some unknown subset of which may be faulty, that communicate only by means of two-party messages. Each nonfaulty processor has a private value of information that must be communicated to each other nonfaulty processor. Nonfaulty processors always communicate honestly, whereas faulty(More)
A method ~s g~ven for dec~dlng formulas in combinations of unquantified first-order theories. Rather than couphng separate decision procedures for the contributing theories, the method makes use of a single, uniform procedure that minimizes the code needed to accommodate each additional theory. It ~s apphcable to theories whose semantics can be encoded(More)
V R Pratt has shown that the real and integer feastbdlty of sets of linear mequallUes of the form x _< y + c can be decided quickly by examining the loops m certain graphs Pratt's method is generahzed, first to real feaslbdlty of mequahues m two variables and arbitrary coefficients, and ultimately to real feaslbdlty of arbitrary sets of hnear mequahtles The(More)
This article presents an improved version of Bledsoe's SUP-INF method for proving theorems in a subclass of Presburger ari thmetic The improved method is able to determine mvahdRy as well as vahdlty, and provides counterexamples for formulas determined to be mvahd A proof of correctness is given for the algorithms on which the method is based Implementat(More)