Knowledge Representation with Attribute Grammars

Παπακωνσταντίνου, Γ.; Kontos, John

doi:10.1093/comjnl/29.3.241

Cited by 32 publications

(11 citation statements)

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“…Attribute grammars have extensively been used for logic programming applications [6,11]. In [12] an effective method based on an extension of the Floyd's parser [7] is presented that transforms a logic program to its AG equivalent representation.…”

Section: Theoretical Definitionsmentioning

confidence: 99%

An Embedded Microprocessor for Intelligent Control

Panagopoulos

Pavlatos

Παπακωνσταντίνου

2005

J Intell Robot Syst

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Abstract. The conventional approach for the implementation of the knowledge base of a planning agent, on an intelligent embedded system, is solely of software nature. It requires the existence of a compiler that transforms the initial declarative logic program, specifying the knowledge base, to its equivalent procedural one, to be programmed to the embedded system's microprocessor. This practice increases the complexity of the final implementation (the declarative to sequential transformation adds a great amount of software code for simulating the declarative execution) and reduces the overall system's performance (logic derivations require the use of a stack and a great number of jump instructions for their evaluation). The design of specialized hardware implementations, which are only capable of supporting logic programs, in an effort to resolve the aforementioned problems, introduces limitations in their use in applications where logic programs need to be intertwined with traditional procedural ones in a desired application. In this paper, we exploit HW/SW codesign methods to present a microprocessor, capable of supporting hybrid applications using both programming approaches. We take advantage of the close relationship between attribute grammar (AG) evaluation and knowledge engineering methods to present a programmable hardware parser that performs logic derivations and combine it with an extension of a conventional RISC microprocessor that performs the unification process to report the success or failure of logic derivations. The extended RISC microprocessor is still capable of executing conventional procedural programs, thus hybrid applications can be implemented. The presented implementation increases the performance of logic derivations for the control inference process (experimental analysis yields an approximate 1000% -10 times increase in performance) and reduces the complexity of the final implemented code through the introduction of an extended C language called C-AG that simplifies the programming of hybrid procedural-declarative applications.

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Section: Theoretical Definitionsmentioning

confidence: 99%

An Embedded Microprocessor for Intelligent Control

Panagopoulos

Pavlatos

Παπακωνσταντίνου

2005

J Intell Robot Syst

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“…It is also semantically driven (supports dynamic parsing by exploiting treepruning techniques to increase efficiency and prevent the memory explosion problem for storing all possible parse trees) and it gives all possible solutions (non-deterministic), that is, it can provide all possible parse trees for a specific input string. Due to the close relation between attribute grammars and logic, it can be easily extended to be used in intelligent embedded systems for logic programming applications [14] [15] and can be extended to support fuzziness and uncertainty [9] [10]. Finally, there are already software implementations of the parser and its use in various application domains providing a sufficient development environment for the evaluation of the design [6] [14] [15].…”

Section: Related Workmentioning

confidence: 99%

“…Attribute grammars (AG) have extensively been used in a considerable number of applications [8] such as knowledge representation [20][4] [14] [15], medical applications [11] [12], waveform analysis [13], hardware compilation [5], etc mainly due to their expressive power and declarative nature, compared to procedural programming equivalent approaches. Therefore, the possibility of exploiting AG evaluation approaches in embedded systems for those application domains is of great importance.…”

Section: Introductionmentioning

confidence: 99%

A hardware extension of the RISC microprocessor for Attribute Grammar evaluation

Panagopoulos

Pavlatos

Παπακωνσταντίνου

2004

Proceedings of the 2004 ACM Symposium on Applied Computing

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Conventional implementations of Attribute Grammar (AG) evaluators in embedded systems today, are solely of software nature. A compiler transforms the parser's specification along with the declarative attribute evaluation rules into a behaviorally equivalent procedural program to be executed on the microprocessor. This approach affects the final system's performance as well as the complexity of the final implementation. Efforts in presenting hardware implementations of AG evaluators, although efficient enough in terms of performance, are usually fully implemented in hardware and as a consequence restricted to a single application. We exploit HW/SW codesign methods in the effort of presenting a hardware implementation of AG evaluators that is both reprogrammable and increases the desired system's performance. We achieve that by extending a conventional RISC microprocessor by combining it with a programmable implementation of a hardware parser to propose a fully programmable AG evaluator that supports the execution of hybrid combinations of declarative-procedural code. The hardware parser increases design efficiency of tree derivations while the RISC microprocessor handles the attribute evaluation computations. As a result, performance is increased while design flexibility required in embedded system applications is preserved.

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“…Attribute grammars have been derived by Knuth [50] as a tool for formal specification of programming languages. They have also been proposed for knowledge representation and logic programming [75], since it was shown that the parsing mechanism and the semantic notation of attribute grammars can be combined to represent the control knowledge and the knowledge base of logic programs, respectively. The practical implementation of this approach to situations where knowledge may be expressed in the form of logic rules has been studied in [76].…”

Section: Ati~ibute Grammar Systemsmentioning

confidence: 99%