Sadaki Hirose

1/ f fluctuation in the “Game of Life”

Abstract The Fourier power spectra are examined for the Game of Life and its variants. The results show that only the Game of Life exhibits fluctuation. By means of observing patterns and measuring entropy and difference pattern spreading rate, we conclude that the Game of Life only belongs to Wolframs class-IV cellular automata which are thought to be capable of supporting universal computation. This predicts a connection between fluctuation and computational universality.

Elevator group control system using multiagent system

In this study, the authors proposed an elevator group control system using multiagent system, and verified the efficiency of the system in areas characterized by concentration of large crowds of passengers on the main floor, for example, during morning rush-hour traffic. Congestion on the main floor in heavy morning rush-hour traffic areas was previously alleviated using specific traffic control systems providing so-called morning rush-hour operation by forced dispatching of multiple elevators to the main floor. However, since forced dispatching on the main floor affects areas other than the main floor and also the subsequent service on the main floor, it makes overall improvement of transportation efficiency a difficult task. There are published reports relating to morning rush-hour operation, but these deal with centralized control based on overall monitoring and sending instruction commands. Thus, the problem is that if this control system stopped working, it caused overall malfunctioning. In addition, in a system based on overall monitoring and generating optimal control plan in accordance with the received information, it is not easy to generate design updates following a change in the systems design or environment. Therefore, in the current study the authors introduced a multiagent system with distributed processing, in which individual elevators make action decisions by independent learning process. The authors proposed an elevator group control system which uses simplified reasoning to provide for flexible response even in the case of a changed environment, such as when a part of the elevator group has stopped functioning.

A homomorphic characterization of recursively enumerable languages

Abstract We give a homomorphic characterization of the class of recursively enumerable languages: it is shown that any recursively enumerable language is the homomorphic image of the intersection of a Dyck language and a ‘minimal linear’ language.

Homomorphic characterizations of recursively enumerable languages with very small language classes

In this paper, we attempt to characterize the class of recursively enumerable languages with much smaller language classes than that of linear languages. Language classes, (i,j)LL and (i,j)ML, of (i,j) linear languages and (i,j) minimal linear languages are defined by posing restrictions on the form of production rules and the number of nonterminals. Then the homomorphic characterizations of the class of recursively enumerable languages are obtained using these classes and a class, ML, of minimal linear languages. That is, for any recursively enumerable language L over Σ, an alphabet Δ, a homomorphism h:Δ∗→Σ∗ and two languages L1 and L2 over Δ in some classes mentioned above can be found such that L=h(L1∩L2). The membership relations of L1 and L2 of the main results are as follows: (I) For posing restrictions on the forms of production rules, the following result is obtained: (1) L1∈(1,2)LL and L2∈(1,1)LL. This result is the best one and cannot be improved using (i,j)LL. However, with posing more restriction on L2, this result can be improved and the follwing statement is obtained. (2) L1∈(1,2)LL and L2∈(1,1)ML. (II) For posing restrictions on the numbers of nonterminals, the follwing result is obtained. (3) L1∈ML and L2∈(1,1)ML. We believe this result is also the best.

On the impossibility of the homomorphic characterization of context sensitive languages

Abstract In this note, we show that for context-sensitive languages there exists no characterization of the same type as described by Chomsky and Stanley for context-free languages.

On the Chomsky and Stanley's homomorphic characterization of context-free languages

Abstract In this note we refine the Chomsky and Stanleys homomorphic characterization of context-free languages: it is shown that each context-free language can be expressed in the form h ( D ∩ M R ) for some Dyck language D , some ‘minimal linear and regular’ language M R and some homomorphism h .

Subclasses of Linear Context—Free Languages and Homomorphic Characterizations of Languages

This paper defines the right-longer (left-longer) linear grammars with the property for every production rule as natural variants of even linear grammars defined The relation is investigated among the language classes generated by those grammars, regular grammars, and linear context-free grammars. Also investigated are the closure properties under some basic set operations. Finally, new homomorphic characterizations are given as follows. For every recursively enumerable language L, we can find two languages L1, L2 from each pair of those language classes except a pair of even linear languages and a homomorphism h such that L=h(L1L2). For the remainder pair, a result that h(L1L2) is linear context-free is obtained.

The firing squad synchronization problem with sub-generals

The Firing Squad Synchronization Problem (FSSP), one of the most well-known problems related to cellular automata, was originally proposed by Myhill in 1957 and became famous through the work of Moore. The first solution to this problem was given by Minsky and McCarthy, and a minimal time solution was given by Goto. A considerable amount of research has also dealt with variants of this problem. In this paper, we introduce a new state called the sub-general to the original problem and propose the FSSP with sub-generals. In particular, we consider the case of one sub-general and determine the position of the sub-general in the array that minimizes the synchronization time. Moreover, we determine the minimal time to solve this problem and show that there exists no minimal time solution for any length of array. However, we show that the total time of our algorithm approaches arbitrarily close to the minimal time.

On Computational Power of Insertion-Deletion Systems without Using Contexts

An Insertion-Deletion system, first introduced in [1], is a theoretical computing model in the DNA computing framework based on insertion and deletion operations. When insertion and deletion operations work together, as expected, they are very powerful. In fact, it has been shown that even the very restricted Insertion-Deletion systems can characterize the class of recursively enumerable languages [1]--[4]. In this paper, we investigate the computational power of Insertion-Deletion systems and show that they preserve the computational universality without using contexts.

A proposal to reduce cumulative reasoning time in hypothetical reasoning

Considered in this paper is a method to reduce cumulative execution time in hypothetical reasoning using inference-path network. Logic-based hypothetical reasoning provides an efficient framework that can be applied to such areas as diagnostics and design, but in so doing, the reasoning speed may prove insufficient. This problem seems to be solvable by using partial hypothetical knowledge. In this case, more than one iteration with partial hypothetical knowledge may be required to find a solution. Some existing techniques involve iterative reasoning within the same knowledge base while varying the hypothetical knowledge; networks are generated as necessary, and hypotheses are synthesized at each iteration. On the contrary, the method proposed in this study involves reduction of execution time by reusing the results of previous reasoning. Specifically, the cumulative execution time is reduced by applying the concept of stage, by partially deterring inference-path generation, and by keeping the results of hypothetical reasoning.