ALGORITHMS FOR FINDING CHOMSKY AND GREIBACH NORMAL FORMS FOR A FUZZY CONTEXT‐FREE GRAMMAR USING AN ALGEBRAIC APPROACH

Kybernetes ◽  
1983 ◽  
Vol 12 (2) ◽  
pp. 125-134 ◽  
Author(s):  
EDWARD T. LEE
Keyword(s):  
Normal Forms ◽  
Algebraic Approach ◽  
Context Free Grammar ◽  
Context Free

A Survey of Normal form Covers for Regular Grammars

1981 ◽  
Vol 4 (4) ◽  
pp. 761-776
Author(s):  
Anton Nijholt
Keyword(s):  
Normal Form ◽  
Special Form ◽  
Normal Forms ◽  
Context Free Grammar ◽  
Left Regular ◽  
Regular Grammar ◽  
Left And Right ◽  
Context Free ◽  
Greibach Normal Form

An overview is given of cover results for normal forms of regular grammars. Due to the special form of regular grammars and due to the results which are obtained it is sufficient to consider covering grammars in Greibach normal form. Among other things it is proved that any left-regular grammar can be left covered with a context-free grammar in Greibach normal form. All the cover results concerning the left- and right-regular grammars are listed, with respect to several types of covers, in a cover table.

Framework for rare event detection using Artificial Neural Network based context free grammar

2020 ◽  
Vol 39 (6) ◽  
pp. 8463-8475
Author(s):  
Palanivel Srinivasan ◽  
Manivannan Doraipandian
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Event Detection ◽  
Performance Metrics ◽  
Rare Events ◽  
Rare Event ◽  
Video Stream ◽  
Context Free Grammar ◽  
Artificial Neural ◽  
Context Free

Rare event detections are performed using spatial domain and frequency domain-based procedures. Omnipresent surveillance camera footages are increasing exponentially due course the time. Monitoring all the events manually is an insignificant and more time-consuming process. Therefore, an automated rare event detection contrivance is required to make this process manageable. In this work, a Context-Free Grammar (CFG) is developed for detecting rare events from a video stream and Artificial Neural Network (ANN) is used to train CFG. A set of dedicated algorithms are used to perform frame split process, edge detection, background subtraction and convert the processed data into CFG. The developed CFG is converted into nodes and edges to form a graph. The graph is given to the input layer of an ANN to classify normal and rare event classes. Graph derived from CFG using input video stream is used to train ANN Further the performance of developed Artificial Neural Network Based Context-Free Grammar – Rare Event Detection (ACFG-RED) is compared with other existing techniques and performance metrics such as accuracy, precision, sensitivity, recall, average processing time and average processing power are used for performance estimation and analyzed. Better performance metrics values have been observed for the ANN-CFG model compared with other techniques. The developed model will provide a better solution in detecting rare events using video streams.

scholarly journals Searching for universal model of amyloid signaling motifs using probabilistic context-free grammars

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Witold Dyrka ◽  
Marlena Gąsior-Głogowska ◽  
Monika Szefczyk ◽  
Natalia Szulc
Keyword(s):  
Functional Relationship ◽  
High Sensitivity ◽  
Alternative Methods ◽  
Discriminative Power ◽  
Context Free Grammar ◽  
Protein Motifs ◽  
Functional Features ◽  
Universal Grammars ◽  
Context Free ◽  
Probabilistic Context

Abstract Background Amyloid signaling motifs are a class of protein motifs which share basic structural and functional features despite the lack of clear sequence homology. They are hard to detect in large sequence databases either with the alignment-based profile methods (due to short length and diversity) or with generic amyloid- and prion-finding tools (due to insufficient discriminative power). We propose to address the challenge with a machine learning grammatical model capable of generalizing over diverse collections of unaligned yet related motifs. Results First, we introduce and test improvements to our probabilistic context-free grammar framework for protein sequences that allow for inferring more sophisticated models achieving high sensitivity at low false positive rates. Then, we infer universal grammars for a collection of recently identified bacterial amyloid signaling motifs and demonstrate that the method is capable of generalizing by successfully searching for related motifs in fungi. The results are compared to available alternative methods. Finally, we conduct spectroscopy and staining analyses of selected peptides to verify their structural and functional relationship. Conclusions While the profile HMMs remain the method of choice for modeling homologous sets of sequences, PCFGs seem more suitable for building meta-family descriptors and extrapolating beyond the seed sample.

A generalization of the concept of a context-free grammar

Cybernetics ◽  
1974 ◽  
Vol 8 (3) ◽  
pp. 349-351
Author(s):  
A. A. Letichevskii
Keyword(s):  
Context Free Grammar ◽  
Context Free

scholarly journals Knowledge Sources for Constituent Parsing of German, a Morphologically Rich and Less-Configurational Language

2013 ◽  
Vol 39 (1) ◽  
pp. 57-85 ◽  
Author(s):  
Alexander Fraser ◽  
Helmut Schmid ◽  
Richárd Farkas ◽  
Renjing Wang ◽  
Hinrich Schütze
Keyword(s):  
State Of The Art ◽  
Lessons Learned ◽  
Knowledge Sources ◽  
Lexical Knowledge ◽  
Context Free Grammar ◽  
The Impact ◽  
Context Free ◽  
Probabilistic Context

We study constituent parsing of German, a morphologically rich and less-configurational language. We use a probabilistic context-free grammar treebank grammar that has been adapted to the morphologically rich properties of German by markovization and special features added to its productions. We evaluate the impact of adding lexical knowledge. Then we examine both monolingual and bilingual approaches to parse reranking. Our reranking parser is the new state of the art in constituency parsing of the TIGER Treebank. We perform an analysis, concluding with lessons learned, which apply to parsing other morphologically rich and less-configurational languages.

scholarly journals Context-free grammar forms with strict interpretations

1980 ◽  
Vol 21 (1) ◽  
pp. 110-135 ◽  
Author(s):  
H.A. Maurer ◽  
A. Salomaa ◽  
D. Wood
Keyword(s):  
Context Free Grammar ◽  
Context Free

scholarly journals Enhanced Arabic Information Retrieval by Using Arabic Slang Language

2019 ◽  
Vol 13 (6) ◽  
pp. 24
Author(s):  
Mustafa Abdel-Kareem Ababneh ◽  
Ghassan Kanaan ◽  
Ayat Amin Al-Jarrah
Keyword(s):  
Information Retrieval ◽  
First Language ◽  
Research System ◽  
System Framework ◽  
Context Free Grammar ◽  
Arabic Information Retrieval ◽  
The Social ◽  
The World ◽  
Context Free ◽  
F Measure

Slang language has become the most used language in the most countries. It has almost become the first language in the social media, websites and daily conversations. Moreover, it has become used in many conferences to clarify information and to deliver the required purpose of them. Therefore, this great spread of slang language over the world. In Jordan indicates that it is important to know meanings of Jordanian slang vocabularies. Mainly, In research system, we created a system framework allows users to restore Arabic information depending on queries that are written in slang language and this framework was made basically by context-free grammar to convert from slang to classical and vice versa. In addition, to conclude with, we will apply it on the colloquial slang in North of Jordan specifically; Irbid, Ajloun, Jerash, Mafraq and AlRamtha city. As well as, we will make a special file for Non_Arabic words and the stop words too. After we made an evaluation for the system relying on the results of recall, precision and F-measure where the results of precision about 0.63 for both researches slang and classical query, and this indicates that the system supports searching in Jordanian slang language. The purpose of this research is to enhance Arabic information retrieval, and it will be a significant resource for researchers who are interested in slang languages. As well as, it helps tie communities together.

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