Allan Borodin

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Turing machine space complexity is related to circuit depth complexity. The relationship complements the known connection between Turing machine time and circuit size, thus enabling us to expose the related nature of some important open problems concerning Turing machine and circuit complexity. We are also able to show some connection between Turing machine(More)
In practice, almost all dynamic systems require decisions to be made on-line, without full knowledge of their future impact on the system. A general model for the processing of sequences of tasks is introduced, and a general on-line decision algorithm is developed. It is shown that, for an important class of special cases, this algorithm is optimal among(More)
A syntactic read-k-times branching program has the restriction that no variable occurs more thank times on any path (whether or not consistent) of the branching program. We first extend the result in [31], to show that the “n/2 clique only function”, which is easily seen to be computable by deterministic polynomial size read-twice programs, cannot be(More)
In practice, almost all dynamic systems require decisions to be made online, without full knowledge of their future impact on the system. We introduce a general model for the processing of sequences of tasks and develop a general online decision algorithm. We show that, for an important class of special cases, this algorithm is optimal among all online(More)
The explosive growth and the widespread accessibility of the Web has led to a surge of research activity in the area of information retrieval on the World Wide Web. The seminal papers of Kleinberg [1998, 1999] and Brin and Page [1998] introduced <i>Link Analysis Ranking</i>, where hyperlink structures are used to determine the relative <i>authority</i> of a(More)
A variety of models have been proposed for the study of synchronous parallel computation. We review these models and study further some prototype problems. We distinguish two classes of models, fixed connection networks and models based on a shared memory. Routing is the prototype problem for the networks. In particular, routing provides the basis for(More)
We study mechanisms for utilitarian combinatorial allocation problems, where agents are not assumed to be single-minded. This class of problems includes combinatorial auctions, multi-unit auctions, unsplittable flow problems, and others. We focus on the problem of designing mechanisms that approximately optimize social welfare at every Bayes-Nash(More)