We consider the problem of traversing skew (unbalanced) Merkle
trees and design an algorithm for traversing a skew Merkle tree
in time O(log n/log t) and space O(log n (t/log t)), for any choice
of parameter t\geq 2.
This algorithm can be of special interest in situations when
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Lovasz and Schrijver described a generic method of tightening the LP and SDP relaxation for any 0-1 optimization problem. These tightened relaxations were the basis of several celebrated approximation algorithms (such as for MAX-CUT, MAX-3SAT, and SPARSEST CUT).

We prove strong nonapproximability results in this model for well-known problems such ... more >>>

We study in this paper the computational complexity of some
equivalence relations on polynomial systems of equations over finite
fields. These problems are analyzed with respect to polynomial-time
many-one reductions (resp. Turing reductions, Levin reductions). In
particular, we show that some of these problems are between ... more >>>