The Kourovka Notebook (Russian: Коуровская тетрадь) is a collection of unsolved problems in group theory, first published in 1965 and updated many times since. [15] The Sverdlovsk Notebook …

A combination puzzle, also known as a sequential move puzzle, is a puzzle which consists of a set of pieces which can be manipulated into different combinations by a group of operations.

A PDF file is organized using ASCII characters, except for certain elements that may have binary content. The file starts with a header containing a magic number (as a readable string) and the …

The popularity of these puzzles guarantees they'd be well known by then to Sam Loyd, an American puzzler and early Dudeney puzzle collaborator. Both Dudeney and Loyd were featured by Martin …

A good puzzle should have one unique solution, and the letters should make up a phrase (as in the example above). Verbal arithmetic can be useful as a motivation and source of exercises in the …

The cutting of the Gordian Knot is a classical example. The term was first used in 1967 by Maltese psychologist Edward de Bono who used the Judgement of Solomon, the Nine Dots Puzzle, and the …