Using XQuery for problem solving

Computer applications have intriguing potential for enhancing human problem-solving capabilities. They allow us to play with ideas in their nascent stage and to experiment with possible solutions. Spreadsheet calculators and scripting languages are often used as ad-hoc tools to replace tedious pen-and-pencil work in such circumstances. The author of this article has previously used script languages like AWK [1] and Python [51], or the logic programming language Prolog [13, 49] for experimenting with combinatorial ideas, and for rapid prototyping of designs, say, of virtual machine architectures, before implementing them in a procedural language like C, Ada, or Java. Recently, XQuery has in several occasions been chosen as a tool for such experiments by the author. We demonstrate the potential of XQuery for experimental problem solving by considering XQuery solutions to several recreational problems and puzzles. We share Donald Knuth’s attitude towards puzzles [33, pp. 7–9]. That is, the puzzles are not the most important thing, but they are ideal for introducing representative problems—and of course, they are fun. The