In an article in the August 1993 Word Ways, Ross Eckler introduced the concept of a word worm, an object defined on the three-dimensional lattice of integer-valued points. Each point on this lattice has 26 neighbors which can be reached by a single orthogonal or diagonal step. These 26 stepping directions are identified with the 26 letters of the alphabet as shown in Figure 1. This positive X direction is defined by the N-step, the positive Y direction, by the K-step, and the positive Z direction, by the E step.
"Knotted Word Worms,"
Word Ways: Vol. 34
, Article 2.
Available at: http://digitalcommons.butler.edu/wordways/vol34/iss1/2