Emergence of Self-Replicating Loops in an Interactive, Hardware-Implemented Game-of-Life Environment - Cellular Automata - page 128

Fig. 7. The BioWall used to physically implement our Life/loop CA. The dots sur-
rounding the loops define visually the loop context (Photograph by A. Badertscher).
4 Emergence of the Loop
The two-dimensional cellular space is initialized as an empty Life environment
where the user can induce the birth of cells by physically touching them. In this
environment, each living cell presents randomly one of the six idle loop states at
each time-step. The context switch between Life and loop happens when a square
block of four adjacent cells detects one of the four configurations of the idle loop
(Figure 4). Without external activation, this newly created loop then remains
idle. Depending on the absence or presence of surrounding loops, the physical
activation of the idle loop induces a self-replication or self-destruction process.
While performing these processes, the cellular space colonized by replication
(Figure 5) shifts to the loop context and the cellular space freed by destruction
(Figure 6) returns to the Life context.
5 Hardware Implementation
We have implemented the nine/five environment of the Life/loop CA in our
interactive reconfigurable computing tissue as an application of the BioWall
(Figure 7). In this hardware implementation, each CA cell corresponds to a cell
in the wall. The touch-sensitive element covering the cell's outer surface acts
like a digital switch, enabling the user to click on the cell and thereby activate