8,656 research outputs found
On two-way communication in cellular automata with a fixed number of cells
The effect of adding two-way communication to k cells one-way cellular automata (kC-OCAs) on their size of description is studied. kC-OCAs are a parallel model for the regular languages that consists of an array of k identical deterministic finite automata (DFAs), called cells, operating in parallel. Each cell gets information from its right neighbor only. In this paper, two models with different amounts of two-way communication are investigated. Both models always achieve quadratic savings when compared to DFAs. When compared to a one-way cellular model, the result is that minimum two-way communication can achieve at most quadratic savings whereas maximum two-way communication may provide savings bounded by a polynomial of degree k
Review of research in feature-based design
Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems do. The evolution of feature definitions is briefly discussed. Features and their role in the design process and as representatives of design-objects and design-object knowledge are discussed. The main research issues related to feature-based design are outlined. These are: feature representation, features and tolerances, feature validation, multiple viewpoints towards features, features and standardization, and features and languages. An overview of some academic feature-based design systems is provided. Future research issues in feature-based design are outlined. The conclusion is that feature-based design is still in its infancy, and that more research is needed for a better support of the design process and better integration with manufacturing, although major advances have already been made
On one-way cellular automata with a fixed number of cells
We investigate a restricted one-way cellular automaton (OCA) model where the number of cells is bounded by a constant number k, so-called kC-OCAs. In contrast to the general model, the generative capacity of the restricted model is reduced to the set of regular languages. A kC-OCA can be algorithmically converted to a deterministic finite automaton (DFA). The blow-up in the number of states is bounded by a polynomial of degree k. We can exhibit a family of unary languages which shows that this upper bound is tight in order of magnitude. We then study upper and lower bounds for the trade-off when converting DFAs to kC-OCAs. We show that there are regular languages where the use of kC-OCAs cannot reduce the number of states when compared to DFAs. We then investigate trade-offs between kC-OCAs with different numbers of cells and finally treat the problem of minimizing a given kC-OCA
Graph Interpolation Grammars: a Rule-based Approach to the Incremental Parsing of Natural Languages
Graph Interpolation Grammars are a declarative formalism with an operational
semantics. Their goal is to emulate salient features of the human parser, and
notably incrementality. The parsing process defined by GIGs incrementally
builds a syntactic representation of a sentence as each successive lexeme is
read. A GIG rule specifies a set of parse configurations that trigger its
application and an operation to perform on a matching configuration. Rules are
partly context-sensitive; furthermore, they are reversible, meaning that their
operations can be undone, which allows the parsing process to be
nondeterministic. These two factors confer enough expressive power to the
formalism for parsing natural languages.Comment: 41 pages, Postscript onl
Type-driven semantic interpretation and feature dependencies in R-LFG
Once one has enriched LFG's formal machinery with the linear logic mechanisms
needed for semantic interpretation as proposed by Dalrymple et. al., it is
natural to ask whether these make any existing components of LFG redundant. As
Dalrymple and her colleagues note, LFG's f-structure completeness and coherence
constraints fall out as a by-product of the linear logic machinery they propose
for semantic interpretation, thus making those f-structure mechanisms
redundant. Given that linear logic machinery or something like it is
independently needed for semantic interpretation, it seems reasonable to
explore the extent to which it is capable of handling feature structure
constraints as well.
R-LFG represents the extreme position that all linguistically required
feature structure dependencies can be captured by the resource-accounting
machinery of a linear or similiar logic independently needed for semantic
interpretation, making LFG's unification machinery redundant. The goal is to
show that LFG linguistic analyses can be expressed as clearly and perspicuously
using the smaller set of mechanisms of R-LFG as they can using the much larger
set of unification-based mechanisms in LFG: if this is the case then we will
have shown that positing these extra f-structure mechanisms is not
linguistically warranted.Comment: 30 pages, to appear in the the ``Glue Language'' volume edited by
Dalrymple, uses tree-dvips, ipa, epic, eepic, fullnam
SAGA: A project to automate the management of software production systems
The Software Automation, Generation and Administration (SAGA) project is investigating the design and construction of practical software engineering environments for developing and maintaining aerospace systems and applications software. The research includes the practical organization of the software lifecycle, configuration management, software requirements specifications, executable specifications, design methodologies, programming, verification, validation and testing, version control, maintenance, the reuse of software, software libraries, documentation, and automated management
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