A private information retrieval scheme is a protocol whereby a client obtains a record from a database without the database operators learning anything about which record the clien...
The trace subshift of a cellular automaton is the subshift of all possible columns that may appear in a space-time diagram. We prove the undecidability of a rather large class of p...
In computability theory, program self-reference is formalized by the not-necessarily-constructive form of Kleene’s Recursion Theorem (krt). In a programming system in which krt h...
Suppose we are given a graph G together with two proper vertex k-colourings of G, α and β. How easily can we decide whether it is possible to transform α into β by recolouring...
Abstract. A famous lower bound for the bilinear complexity of the multiplication in associative algebras is the Alder–Strassen bound. Algebras for which this bound is tight are c...
Abstract. We examine computational problems on quaternion matrix and rotation semigroups. It is shown that in the ultimate case of quaternion matrices, in which multiplication is s...
Following recent works connecting two-variable logic to circuits and monoids, we establish, for numerical predicate sets P satisfying a certain closure property, a one-to-one corre...