was generated by repeated application of "Rule 254". The automaton was initialized with an input line that consisted of a single black square. Repeated application of rule 254 to the ouput line from the preceding step generated the black triangle shown above.
For this rule, the top row in each box gives one of eight possible color combinations for a cell (the middle cell) and its two neighbors (the left and right neighbors of the cell). The bottom row in a box specifies the color that the center cell should have on the next step for each of the 8 possible cases. Given this arrangement, there are 255 different generating rules or automata numbered as follows:
The "Bounded" Automata
- Unlike the automata in "A New Kind of Science", the automata for this problem operate in a "bounded space". In other words, each line output by an automaton consists of exactly n squares, and, the first square, and the last square of the output from a bounded automaton are always white no matter what the rule for the automata. This means that while an automaton can examine the first and last square of its input line when computing the new second and second to last characters, it cannot change the first or last square when it outputs a line. Thus, the first and the last square on a line must always remain white.
- Bounded automata will always start life on a line with an odd number of squares, and all of the squares (except the middle square) are white. The middle square for step 1 is always black.
- The number of squares is determined by the string for which the program is searching (the second field of an input line)