Grammars and languages: Chomsky’s hierarchy
N. Chomsky: Three models are there for the explanation of language.
Motivating illustration:
Sentence -> Noun Verb Noun, example: Bob loves Alice.
Sentence -> Sentence Conjunction Sentence, example: Bob loves Alice and Rome fights Carthage.
Grammar G(V, A, P, S). V: alphabet of the non-terminal symbols, variables and grammatical types;
A: alphabet of the terminal symbols, S ∈ V: start symbol, ‘sentence’;
P: unordered set of the productions of form L -> R, where L, R ∈ (V ∪ A)*
Rewriting step: for x, y, y’, z ∈ (V ∪ A)*, u -> v if u = xyz, v = xy’z and y -> y’ ∈ P
Derivation: “->*” is the transitive, reflexive closure of “->”, that is, u ->* v iff ∃ w0, w1 ... wj, with j ≥ 0, u = w0, w(i-1) -> wi, wj = v
Language defined by G: L(G) = {w ∈ A* | S ->* w)
Different restrictions on the productions define various types of grammars and corresponding languages:
Type 0: Phrase structure grammar: No restrictions
Type 1: Context sensitive: |L| ≤ |R|, (exception: S -> ε is permitted when S never takes place on any right-hand side)
Type 2: context free: L ∈ V
Type 3: regular: L ∈ V, R = a or R = aX, where a ∈ A, X ∈ V
Exercise: Define a grammar for some very small subset of natural language, and exemplify it with illustrations. Try this for a subset of English and a semantically identical subset of the other language, and show that distinct natural languages encompass different grammars.
Latest technology based Theory of Computation Online Tutoring Assistance
Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in Theory of Computation help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for Theory of Computation, project ideas and tutorials. We provide email based Theory of Computation help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in Theory of Computation. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Theory of Computation Homework help and assignment help services. They use their experience, as they have solved thousands of the Theory of Computation assignments, which may help you to solve your complex issues of Theory of Computation. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.
tutorsglobe.com gaseous exchange in the alveoli assignment help-homework help by online respiration tutors
Free GMAT Study Guide, GMAT Test Papers, GMAT Practice papers, GMAT Test pattern and general information, Find GMAT exam information and resource, material free at Tutorsglobe.com
tutorsglobe.com five kingdom system of classification assignment help-homework help by online systematics tutors
tutorsglobe.com sustainable scientific methods of farming assignment help-homework help by online sustained agriculture tutors
tutorsglobe.com xeric habitats characterization assignment help-homework help by online xerophytes tutors
TutorsGlobe.com Solids Assignment Help-Homework Help by Online Access Chemistry Tutors
Theory and lecture notes of Euler Methods all along with the key concepts of differential equations, Modified Euler Method, problem with the Euler method, Numerical Solution of an IVP. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Euler Methods.
Seedless plants and Spermatophytes tutorial all along with the key concepts of Division Bryophyta, Division Pteridophyta, The Spermatophytes and Division Angiospermae
www.tutorsglobe.com offers answering questions to theories of international trade, the principle of absolute advantage, economics assignment help - homework help by online tutors.
tutorsglobe.com adverse selection assignment help-homework help by online imperfect information tutors
online regents exam preparation course and online regents tutoring package offered by TutorsGlobe are the most comprehensive and customized collection of study resources on the web, offering best collection of regents practice papers, quizzes, regents test papers, and guidance.
tutorsglobe.com morphological adaptations assignment help-homework help by online hydrophytes tutors
tutorsglobe.com conversion of acetyl coa assignment help-homework help by online biosynthesis of fatty acids tutors
tutorsglobe.com debt securitization assignment help-homework help by online source of finance tutors
tutorsglobe.com kuhne’s fermentation tube experiment assignment help-homework help by online respiration tutors
1936631
Questions Asked
3689
Tutors
1441108
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!