Word squares have been around for literally thousands of years (the oldest known example has been found in ruins across the Roman Empire, including the walls of Pompeii). Each word square is a group of words, all of the same length, arranged so the word in row one is the same as that in column one; row two the same as column two; and so forth. Easy word squares are four-by-four; much harder are eight-by-eights; given a few letter clues, the goal is to fill a perfect word square. In this book, puzzle master Alastair Chisholm has produced 201 brainteasers--from Delicious to Vicious--that will stretch your vocabulary and challenge your puzzle solving skills.

This book constitutes the refereed proceedings of the 12th International Conference on Combinatorics on Words, WORDS 2019, held in Loughborough, UK, in September 2019. The 21 revised full papers presented in this book together with 5 invited talks were carefully reviewed and selected from 34 submissions. WORDS is the main conference series devoted to the mathematical theory of words. In particular, the combinatorial, algebraic and algorithmic aspects of words are emphasized. Motivations may also come from other domains such as theoretical computer science, bioinformatics, digital geometry, symbolic dynamics, numeration systems, text processing, number theory, etc.

The Book of Squares by Fibonacci is a gem in the mathematical literature and one of the most important mathematical treatises written in the Middle Ages. It is a collection of theorems on indeterminate analysis and equations of second degree which yield, among other results, a solution to a problem proposed by Master John of Palermo to Leonardo at the Court of Frederick II. The book was dedicated and presented to the Emperor at Pisa in 1225. Dating back to the 13th century the book exhibits the early and continued fascination of men with our number system and the relationship among numbers with special properties such as prime numbers, squares, and odd numbers. The faithful translation into modern English and the commentary by the translator make this book accessible to professional mathematicians and amateurs who have always been intrigued by the lure of our number system.

On Crosswords covers three major, interrelated topics: crossword history, kinds of crosswords and how crosswords relate to everything else. “Everything else” includes a breathtaking range of topics: marriage proposals, national politics, software development, counterespionage, typography and racism are just some of the high points. Readers will meet the personalities who have made the art form what it is today, and discover the many subspecies of crossword, each with its own personality. And they will walk away with the most complete understanding of the form that any single book can give.