Article Title

Symmetric Crash Groups


A. Ross Eckler


Two words of the same length are said to crash if they have matching letters in one or more positions, such as tIger and pIous, or roTuND and atTeND. A symmetric crash group is a set of words in which (1) each word crashes exactly n times with each other word, (2) every letter participates in a crash, and (3) each letter is used exactly m times in a given position.