We examine some recent work which has made significant progress in out understanding of algorithmic randomness, relative algorithmic randomness and their relationship with algorithmic computabilityâ€¦ (More)

The goal of this article is to provide a tourist guide, with an eye towards structural issues, to what I consider some of the major highlights of parameterized complexity.

We introduce techniques that allow us to embed below an arbitary nonlow2 recursively enumerable degree any lattice currently known to be embedable into the recursively enumerable degrees.

We analyse basic structural aspects of the reducibilities we use to describe fixed parameter tractability and intractability, in the model we introduced in earlier papers in this series. Resultsâ€¦ (More)

If we study the boolean algebra generated by the recursively enumerable sets we are naturally led to the difference hierarchy of Ershov [6,7,8]. If a set A can be represented as (A1 â€” A2) U ... Uâ€¦ (More)

Studies were conducted to investigate the crossability of the cultivated Brassica species, Brassica napus (oilseed rape), B. rapa (turnip rape), and B. juncea (brown and oriental mustard), with twoâ€¦ (More)

We investigate the connections between the complexity of a c.e. set, as calibrated by its strength as an oracle for Turing computations of functions in the Ershov hierarchy, and how strongâ€¦ (More)

We investigate the connections between the complexity of a c.e. set, as calibrated by its strength as an oracle for Turing computations of functions in the Ershov hierarchy, and how strongâ€¦ (More)

Experiments using a Ca2+/Mg2+, serum free media were carried out aimed at clarifying proposed effects of these divalent cations on in vitro meiotic maturation of mouse and cow oocytes. Agents knownâ€¦ (More)