Type 17 designs are made up of polyomino shapes. The term is a mathematical one of recent coinage ( coined bypolyomino American mathematician Solomon W. Golomb, who has written a book on the subject). A polyomino is a two-dimensional shape formed of identical squares that attach themselves to each other corner-to-corner and end-to-end. The simplest example, a, a 1:2 rectangle, is known from the popular board game. A two dimensional domino, unlike the Dominoes playing piece, has no thickness. It is a polyomino contructed with two squares. A polyomino of three squares is a domino or tromino, as it is also called. There are two possible triomino shapes: a 1:3 rectangle and an L shape. This L shape, the tromino (sometimes also called the L tromino) is one of the commonest and most basic shapes of of the Type 17 designs. Other shapes made of more squares are the right tromino (made of four squares, with 5 possible shapes), thetetrominoes (made of five squares and having 12 possible shapes). As more squares are added the possibilities increase geometrically. Not all the shapes are artistically interesting to me, and I tend to use many types of L shapes as they make more interesting designs. pentominoesMany Type 7 designs are solid, that is, they have no negative space. Some have negative space, usually with squares and rectangles forming the negative (or left-over) space. A few border designs consist of shapes that are surrounded by much space. Some consist of shapes that articulate with bands. In terms of the number of designs, this is my largest category, with over 2,600 designs. The Type 17 sub-family of the Series, is discussed in the section for that group.N.S.A.P |