Transmitting-state invertible cellular automata

Invertible cellular automata are useful as models of physical systems with microscopically revesible dyanmics. There are several well-understood ways to construct them: partitioning rules, second-order rules, and alternating-grid rules. We present another way (a generalization of the alternating-grid approach), based on the idea that a cell may either transmit information to its neighbors or receive information from its neighbors, but not both at the same time. We also examine an interesting simple example of this class of rules, one with an additive conserved "energy".Comment: 13 pages, 5 figure