Isomorphism problems often can be solved by determining orbits of a group acting on the set of all objects to be classiied. The paper centers around algorithms for this topic and shows how to base them on the same idea, the homomorphism principle. Especially it is shown that forming Sims chains, using an algorithmic version of Burnside's table of marks, computing double coset representatives, a...

The water table, as used routinely by hydrologists in various disciplines, is seemingly a simple concept: it marks the top of saturated zone porous media. But closer inspection reveals that much theory and practice concerning table are less straightforward than often assumed. We review departures from classical definition consider following phenomena: perched inverted tables, gas bubbles within...

This is the first comprehensive history and survey of buoys, landmarks, lighthouses and other guides to navigation. It represents an enormous amount of research by the author, the well known retired Bristol Physician, John Naish. That it gave him a lot of pleasure comes through in the text, which is written in a way that is both authoritative and interesting, even to a landlubber. He traces the...