Showing papers on "Chomsky hierarchy published in 1993"
TL;DR: This paper applies the method to obtain simple demonstrations of Faa di Bruno's formula, and some identities concerning Bell polynomials, Stirling numbers and symmetric functions, and sees that Cayley's formula on labeled trees is equivalent to the Lagrange inversion formula.
72 citations
08 Nov 1993
TL;DR: In this paper, the authors give a theoretical foundation of machine discovery from examples and point out that the essence of a machine discovery logic is the refutability of the entire spaces of hypotheses.
Abstract: This paper intends to give a theoretical foundation of machine discovery from examples. We point out that the essence of a logic of machine discovery is the refutability of the entire spaces of hypotheses. We discuss this issue in the framework of inductive inference of length-bounded elementary formal systems (EFS's, for short), which are a kind of logic programs over strings of characters and correspond to context-sensitive grammars in Chomsky hierarchy.
37 citations
TL;DR: This paper deals with closure properties of such “slender” languages with respect to a number of operations, some of them introduced very recently.
22 citations
01 Feb 1993
TL;DR: This paper presents a comparison between eight speci cation languages discussed during the Workshop on Formal SpeciCation Techniques for Com plex Reasoning Systems held in Vienna during the ECAI conference.
Abstract: This paper presents a comparison between eight speci cation languages discussed during the Workshop on Formal Speci cation Techniques for Com plex Reasoning Systems held in Vienna during the ECAI conference The languages as discussed here possess many important common characteristics but also di er substantially The analysis discussed here departs from look ing at the purposes of the presented languages Section The comparison in Section focuses on the way of dealing with heuristic knowledge in the speci cation of the common example task In Section some di erences between the languages are discussed
10 citations
18 May 1993
TL;DR: The concept of unambiguity, common to both areas, is treated in detail and some new results on deterministic families of formal languages and on complexities of operations on formal languages are indicated.
Abstract: Some connections between formal languages and complexity are reviewed. Families of formal languages are treated with complexity theoretical methods. In particular, the concept of unambiguity, common to both areas, is treated in detail. Some new results on deterministic families of formal languages and on complexities of operations on formal languages are indicated. >
9 citations
01 Jan 1993
6 citations
Posted Content•
TL;DR: After reviewing some results of the complexity of CA-invariant subshifts, special attention is given to a new kind of invariant subshift: the trapped set, which originates from the theory of chaotic scattering and for which one can study complexity transitions.
Abstract: We treat here the interrelation between formal languages and those dynamical systems that can be described by cellular automata (CA). There is a well-known injective map which identifies any CA-invariant subshift with a central formal language. However, in the special case of a symbolic dynamics, i.e. where the CA is just the shift map, one gets a stronger result: the identification map can be extended to a functor between the categories of symbolic dynamics and formal languages. This functor additionally maps topological conjugacies between subshifts to empty-string-limited generalized sequential machines between languages. If the periodic points form a dense set, a case which arises in a commonly used notion of chaotic dynamics, then an even more natural map to assign a formal language to a subshift is offered. This map extends to a functor, too. The Chomsky hierarchy measuring the complexity of formal languages can be transferred via either of these functors from formal languages to symbolic dynamics and proves to be a conjugacy invariant there. In this way it acquires a dynamical meaning. After reviewing some results of the complexity of CA-invariant subshifts, special attention is given to a new kind of invariant subshift: the trapped set, which originates from the theory of chaotic scattering and for which one can study complexity transitions.
5 citations
TL;DR: This comparison of k-limited and regulated ETOL systems considers regular control, which has not been considered by Watjen (1993), which is not included in this comparison.
4 citations
01 Jan 1993
3 citations
TL;DR: This paper introduces a new level into the Chomsky of formal languages, where the content-free languages are a subset of the regular languages.
Abstract: This paper introduces a new level into the Chomsky of formal languages. Specifically the content-free languages are a subset of the regular languages. Content-free languages have many interesting properties.