Pentomino

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A pentomino is a polyomino composed of five (Greek ¿¿¿¿¿ / pente) congruent squares, connected along their edges (which sometimes is said to be orthogonal connection). There are 12 different pentominoes, often named after the letters of the Latin alphabet that they vaguely resemble. Ordinarily, the pentomino obtained by reflection or rotation of a pentomino does not count as a different pentomino. The F, L, N, P, Y, and Z pentominoes are chiral in two dimensions; adding their reflections (F', J, N', Q, Y', S) brings the number of "one-sided" pentominoes to 18. The others, lettered I, T, U, V, W, and X, are equivalent to some rotation of their mirror images. This matters in some computer games, where mirror image moves are not allowed, such as Tetris-clones and Rampart.