We consider several types of pure grammars as language acceptors and compare them to their genera... more We consider several types of pure grammars as language acceptors and compare them to their generating counterparts. The focus is on pure grammars with controlled derivations (regulated rewriting). Interestingly, we get (non-trivial) inclusion results between language families generated and accepted by numerous types of pure grammars which are rather seldom in the theory of pure grammars.
We consider cooperating distributed (CD) grammar systems and variants thereof as language accepto... more We consider cooperating distributed (CD) grammar systems and variants thereof as language acceptors. If the CD grammar systems work in the modes ..., then their generating capacity equals their accepting capacity. Contrary to this, we obtain a new characterization of the context-sensitive languages by accepting CD grammar systems (with or without l-productions) working in t-mode. Moreover, accepting hybrid CD (HCD) grammar systems with l-productions characterize the recursively enumerable languages.
A method and device for adjusting camber and caster in a solid axle steerable structure including... more A method and device for adjusting camber and caster in a solid axle steerable structure including a yoke, and a steering knuckle rotatably carried in the yoke by a pair of ball joints, by inserting a connecting offset and/or skewed bushing in at least one of the ball joint receiving openings in the yoke and positioning the connecting bushing to accommodate the steering knuckle in the desired, aligned position relative to the yoke.
International Journal of Foundations of Computer Science, 2007
We continue our investigation of the generative power of cooperating distributed grammar systems ... more We continue our investigation of the generative power of cooperating distributed grammar systems (CDGSs), using the previously introduced ≤k-, =k-, and ≥k-competence-based cooperation strategies and context-free components that rewrite the sentential form in a parallel manner. This leads to new characterizations of the languages generated by (random context) ET0L systems and recurrent programmed grammars.
International Journal of Computer Mathematics, 2006
ABSTRACT In this paper we examine context-free cooperating distributed (CD) grammar systems where... more ABSTRACT In this paper we examine context-free cooperating distributed (CD) grammar systems where the cooperation protocol is based on the competence (capability) of the component grammars in rewriting. We study the power of a derivation mode where every component is allowed to start the generation only if it has a prescribed level of competence and it is allowed to finish the work if it is not competent anymore. The competence level of a component on a string is the number of different nonterminals in this word that can be rewritten by the production set of the grammar. We show that if the prescribed level of competence of the grammar to start the derivation is equal to k or is at least k, for some natural number k ≥ 2, then these CD grammar systems are as powerful as the ET0L systems with random context conditions. If this competence level is exactly one, or at least one, or it is at most k, where k ≥ 2, then the class of ET0L languages is determined by these constructions.
International Journal of Computer Mathematics, 1992
ABSTRACT Cooperating/distributed grammar systems are a formal model of blackboard architectures f... more ABSTRACT Cooperating/distributed grammar systems are a formal model of blackboard architectures for problem solving. We introduce different notions of acceptance of a sentential form as a solution. We compare them with respect to the generative power and present statements on the hierarchy according to the number of grammars in the systems with different acceptance styles.
We investigate the operation problem for linear and deterministic context-free languages: Fix an ... more We investigate the operation problem for linear and deterministic context-free languages: Fix an operation on formal languages. Given linear (deterministic, respectively) context-free languages, is the application of this operation to the given languages still a linear (deterministic, respectively) context-free language? Besides the classical operations, for which the linear and deterministic context-free languages are not closed, we also consider the recently
Input-reversal pushdown automata are pushdown automata with the additional power to reverse the u... more Input-reversal pushdown automata are pushdown automata with the additional power to reverse the unread part of the input. We show that these machines characterize the family of linear context-free indexed languages, and that k + 1 input reversals are better than k for both deterministic and nondeterministic input-reversal pushdown automata, i.e., there are languages which can be recognized by a deterministic
We consider several types of pure grammars as language acceptors and compare them to their genera... more We consider several types of pure grammars as language acceptors and compare them to their generating counterparts. The focus is on pure grammars with controlled derivations (regulated rewriting). Interestingly, we get (non-trivial) inclusion results between language families generated and accepted by numerous types of pure grammars which are rather seldom in the theory of pure grammars.
We consider cooperating distributed (CD) grammar systems and variants thereof as language accepto... more We consider cooperating distributed (CD) grammar systems and variants thereof as language acceptors. If the CD grammar systems work in the modes ..., then their generating capacity equals their accepting capacity. Contrary to this, we obtain a new characterization of the context-sensitive languages by accepting CD grammar systems (with or without l-productions) working in t-mode. Moreover, accepting hybrid CD (HCD) grammar systems with l-productions characterize the recursively enumerable languages.
A method and device for adjusting camber and caster in a solid axle steerable structure including... more A method and device for adjusting camber and caster in a solid axle steerable structure including a yoke, and a steering knuckle rotatably carried in the yoke by a pair of ball joints, by inserting a connecting offset and/or skewed bushing in at least one of the ball joint receiving openings in the yoke and positioning the connecting bushing to accommodate the steering knuckle in the desired, aligned position relative to the yoke.
International Journal of Foundations of Computer Science, 2007
We continue our investigation of the generative power of cooperating distributed grammar systems ... more We continue our investigation of the generative power of cooperating distributed grammar systems (CDGSs), using the previously introduced ≤k-, =k-, and ≥k-competence-based cooperation strategies and context-free components that rewrite the sentential form in a parallel manner. This leads to new characterizations of the languages generated by (random context) ET0L systems and recurrent programmed grammars.
International Journal of Computer Mathematics, 2006
ABSTRACT In this paper we examine context-free cooperating distributed (CD) grammar systems where... more ABSTRACT In this paper we examine context-free cooperating distributed (CD) grammar systems where the cooperation protocol is based on the competence (capability) of the component grammars in rewriting. We study the power of a derivation mode where every component is allowed to start the generation only if it has a prescribed level of competence and it is allowed to finish the work if it is not competent anymore. The competence level of a component on a string is the number of different nonterminals in this word that can be rewritten by the production set of the grammar. We show that if the prescribed level of competence of the grammar to start the derivation is equal to k or is at least k, for some natural number k ≥ 2, then these CD grammar systems are as powerful as the ET0L systems with random context conditions. If this competence level is exactly one, or at least one, or it is at most k, where k ≥ 2, then the class of ET0L languages is determined by these constructions.
International Journal of Computer Mathematics, 1992
ABSTRACT Cooperating/distributed grammar systems are a formal model of blackboard architectures f... more ABSTRACT Cooperating/distributed grammar systems are a formal model of blackboard architectures for problem solving. We introduce different notions of acceptance of a sentential form as a solution. We compare them with respect to the generative power and present statements on the hierarchy according to the number of grammars in the systems with different acceptance styles.
We investigate the operation problem for linear and deterministic context-free languages: Fix an ... more We investigate the operation problem for linear and deterministic context-free languages: Fix an operation on formal languages. Given linear (deterministic, respectively) context-free languages, is the application of this operation to the given languages still a linear (deterministic, respectively) context-free language? Besides the classical operations, for which the linear and deterministic context-free languages are not closed, we also consider the recently
Input-reversal pushdown automata are pushdown automata with the additional power to reverse the u... more Input-reversal pushdown automata are pushdown automata with the additional power to reverse the unread part of the input. We show that these machines characterize the family of linear context-free indexed languages, and that k + 1 input reversals are better than k for both deterministic and nondeterministic input-reversal pushdown automata, i.e., there are languages which can be recognized by a deterministic
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