## Reversible rules

Edward Fredkin has proposed a type of direct product automaton which is reversible. Provision exists in the appropriate LCAU programs for generating the rule table for such automata, as well as the tables for their inverses.

- m a - Fredkin automaton using rule a and XOR
- M a - Inverse automaton using rule a and XOR
- n a - Fredkin automaton using rule a and XNOR
- N a - Inverse automaton using rule a and XNOR

Harold V. McIntosh

E-mail:mcintosh@servidor.unam.mx