Four-dimensional Automata Research Articles

Cooperating systems of four-dimensional finite automata

M. Blum and C. Hewitt first proposed two-dimensional automata as a computational model of two-dimensional pattern processing in 1967, and investigated their pattern recognition abilities. Since then, many researchers in this field have investigated many properties of automata on a two- or three-dimensional tape. However, the question of whether processing four-dimensional digital patterns is much more difficult than processing two- or three-dimensional ones is of great interest from both theoretical and practical standpoints. Thus, the study of four-dimensional automata as a computational model of four-dimensional pattern processing has been meaningful. This article introduces a cooperating system of four-dimensional finite automata as one model of four-dimensional automata. A cooperating system of four-dimensional finite automata consists of a finite number of four-dimensional finite automata and a four-dimensional input tape, where these finite automata work independently (in parallel). The finite automata whose input heads scan the same cell of the input tape can communicate with each other, i.e., every finite automaton is allowed to know the internal states of other finite automata on the cell it is scanning at the moment. In this article we mainly investigate the accepting powers of a cooperating system of seven-way four-dimensional finite automata. The seven-way four-dimensional finite automaton is a four-dimensional finite automaton whose input head can move east, west, south, north, up, down, or in the future, but not in the past, on a four-dimensional input tape.

Bottom-up pyramid cellular acceptors with four-dimensional layers

In 1967, M. Blum and C. Hewitt first proposed two-dimensional automata as a computational model of two-dimensional pattern processing. Since then, many researchers in this field have been investigating the many properties of two- or three-dimensional automata. In 1977, C.R. Dyer and A. Rosenfeld introduced an acceptor on a two-dimensional pattern (or tape) called the pyramid cellular acceptor, and demonstrated that many useful recognition tasks are executed by pyramid cellular acceptors in a time which is proportional to the logarithm of the diameter of the input. They also introduced a bottom-up pyramid cellular acceptor, which is a restricted version of the pyramid cellular acceptor, and proposed some interesting open problems about bottom-up pyramid cellular acceptors. On the other hand, we think that the study of four-dimensional automata has been meaningful as the computational model of four-dimensional information processing such as computer animation, moving picture processing, and so forth. In this article, we investigate bottom-up pyramid cellular acceptors with four-dimensional layers, and show some of their accepting powers.

A relationship between Turing machines and finite automata on four-dimensional input tapes

Due to the advances in computer animation, motion image processing, virtual reality systems, and so forth recently, it is useful for analyzing computation of multi-dimensional information processing to explicate the properties of four-dimensional automata. From this point of view, we first proposed four-dimensional automata in 2002, and investigated their several accepting powers. In this paper, we coutinue the study, and mainly concentrate on investigating the relationship between the accepting powers of four-dimensional finite automata and seven-way four-dimensional tape-bounded Turing Machines.

Some properties of four-dimensional multicounter automata

Recently, due to the advances in many application areas such as computer animation, motion image processing, and so forth, it has become increasingly apparent that the study of four-dimensional pattern processing is of crucial importance. Thus, we think that research into four-dimensional automata as a computational model of four-dimensional pattern processing is also meaningful. This article introduces four-dimensional multicounter automata, and investigates some of their properties. We show the differences between the accepting powers of seven-way and eight-way four-dimensional multicounter automata, and between the accepting powers of deterministic and nondeterministic seven-way four-dimensional multicounter automata.

A note on two-dimensional finite automata

During the past about thirty-five years, many types of twoor three-dimensional automata have been proposed and investigated the properties of them as the computational model of pattern processing. On the other hand, recently, due to the advances in many application areas such as computer animation, motion image processing, and so on, the study of three-dimensional pattern processing with the time axis has been of crucial importance. Thus, we think that it is very useful for analyzing computation of three-dimensional pattern processing with the time axis to explicate the properties of four-dimensional automata. In this paper, we propose a four-dimensional Turing machine and a four-dimensional finite automaton, and show the space complexities necessary and sufficient for seven-way four-dimensional Turing machines to simulate four-dimensional finite automata, where each sidelength of each input tape of these automata is equivalent. Key-Words: Turing machine, finite automaton, on-line tessellation acceptor, four-dimensional input tape, determinism, nondeterminism, space-bound, configuration, computation, space complexity