Tomás Oliveira e Silva

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This paper presents some results concerning the search for initial values to the so-called 3x+1 problem which give rise either to function iterates that attain a maximum value higher than all function iterates for all smaller initial values, or which have a stopping time higher than those of all smaller initial values. Our computational results suggest that(More)
This article proposes a massively parallel identification scheme of vehicle RFID tags. These tags use a pseudo-random identifier, which is the output of a hash function fed by a fixed secret key that uniquely identifies the tag and by two random challenges that change on each tag activation. The use of random challenges makes it extremely difficult for(More)
– This article presents a self-contained description of the method proposed by Deléglise and Rivat — which has roots on earlier work by Meissel, by Lehmer, and by Lagarias, Miller and Odlyzko — to compute π(x), which is the number of primes not larger than x. To make life easier to programmers, the major parts of the computation of π(x) are also presented(More)