Alastair Chisholm is based in Edinburgh, Scotland, and is the author of "The Kakuro Challenge # 1" and "# 2," as well as "The Mammoth Book of Sudoku & Kakuro" and "The Essential Book of Advanced Sudoku # 3," As a programmer and puzzle addict, he has spent his time devising and tackling logic problems. Visit his web sites at www.sudoku-san.com and www.kakuro-san.com.