Tsunehiro Yoshinaga

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This paper investigates in3nite hierarchies on alternation-depth and alternation-size of alternating pushdown automata (apda’s) with sublogarithmic space. We 3rst show that there is an in3nite hierarchy on alternation-depth for apda’s with sublogarithmic space. We next investigate a relationship between alternation-depth and alternation-size, and show that(More)
The recent advances in computer animation, motion image processing, robotics and so on prompted us to analyze computational complexity of four-dimensional pattern processing. Thus, the research of four-dimensional automata as a computational model of four-dimensional pattern processing has also been meaningful. From this viewpoint, we introduced a(More)
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)(More)
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(More)