Trips on Trees

Joost Engelfriet*, Hendrik Jan Hoogeboom*, Jan-Pascal Van Best 1

Abstract

 A ``trip'' is a triple (g,u,v) where g is, in general, a graph and u and v are nodes of that graph. The trip is from u to v on the graph g. For the special case that g is a tree (or even a string) we investigate ways of specifying and implementing sets of trips. The main result is that a regular set of trips, specified as a regular tree language, can be implemented by a tree-walking automaton that uses marbles and one pebble.

Footnotes:

  1 Department of Computer Science, Leiden University P.O.Box 9512, 2300 RA Leiden, The Netherlands e-mail: engelfri@wi.leidenuniv.nl