How many possible sudoku puzzles are there? In the lottery, what is the chance that two winning balls have consecutive numbers? Who invented Pascal's triangle? (it was not Pascal)
Combinatorics, the branch of mathematics concerned with selecting, arranging, and listing or counting collections of objects, works to answer all these questions. Dating back some 3000 years, and initially consisting mainly of the study of permutations and combinations, its scope has broadened to include topics such as graph theory, partitions of numbers, block designs, design of codes, and latin squares. In...

The Northern Ireland Experience of Conflict and Agreement presents a salutary warning to the international community against the fashionable view that there is an 'Irish model' which can be exported to cauterise ethnic troubles around the globe. The book draws on extensive archive research in London and Dublin on the 1970s power-sharing experiment, and on interviews with senior officials and political figures from the two capitals-as well as reconciliation practitioners-about the negotiation and chequered implementation of the Belfast agreement. It shows how stereotyped conceptions of the...