Parallel / Sequential Array Automata

the past few years thcrc has been increast in the study of two-dimensional automata types. One can consider two-dimenuonal automata that cperate sequentially by moving (up, down, r&&t, or left) from cell to cell of a t wo-dimensional input tape. .4t the opposite extreme, one can sider two-dimennonal arrays of automata, each nccted to its (north, south, east, and west) neigh, where the array operates in parallel. Selkow [ 1 ] has introduced a “mixes” type of mchine which is essentially a one=dimensional (e.g., :wrizontal) array of automata that can move, as a Wt. in the vertical direction. However, his definition does not satisfy the finiteness restrictio:ls that are usually imposed on such machines. In particular. he allows each automatoil to accept inputs from an arbitrary set of the others and not just from a fixed number of ne@hbo n addition, he defines accep tance of an array usi a counter that cumulatively sums the outputs 0 automata each time the arown one row, and that can count module is allowed to grow @i th the array size. this note is to consider more conf defining a Selkow-type parallel/ machine, and to compare the power e with that of an allhim. 11 should be pointed out that tial machines may well be of consideral picture processing, since they pr#ide a corn li:2 between purely se.