Formal languages

Greibach normal form

In formal language theory, a context-free grammar is in Greibach normal form (GNF) if the right-hand sides of all production rules start with a terminal symbol, optionally followed by some variables. A non-strict form allows one exception to this format restriction for allowing the empty word (epsilon, ε) to be a member of the described language. The normal form was established by Sheila Greibach and it bears her name. More precisely, a context-free grammar is in Greibach normal form, if all production rules are of the form: where is a nonterminal symbol, is a terminal symbol, is a (possibly empty) sequence of nonterminal symbols not including the start symbol and is the start symbol. Observe that the grammar does not have left recursions. Every context-free grammar can be transformed into an equivalent grammar in Greibach normal form. Various constructions exist. Some do not permit the second form of rule and cannot transform context-free grammars that can generate the empty word. For one such construction the size of the constructed grammar is O(n4) in the general case and O(n3) if no derivation of the original grammar consists of a single nonterminal symbol, where n is the size of the original grammar. This conversion can be used to prove that every context-free language can be accepted by a real-time (non-deterministic) pushdown automaton, i.e., the automaton reads a letter from its input every step. Given a grammar in GNF and a derivable string in the grammar with length n, any top-down parser will halt at depth n. (Wikipedia).

Video thumbnail

Physics - Optics: Diffraction Grating (4 of 7) Orders of the Diffraction Grating

Visit http://ilectureonline.com for more math and science lectures! In this video I will discuss the orders of the diffraction grating and find its “look-up” angle. Next video in series: http://youtu.be/29NvhEK0g0s

From playlist PHYSICS 61 DIFFRACTION OF LIGHT

Video thumbnail

Universal Law of Gravitation - Part 2 | Physics | Don't Memorise

This video explains the concept of the Universal Law of Gravitation. ✅To learn more about Gravitation, enroll in our full course now: https://infinitylearn.com/microcourses?utm_source=youtube&utm_medium=Soical&utm_campaign=DM&utm_content=lbOXZ2tcTgc&utm_term=%7Bkeyword%7D In this video,

From playlist Physics

Video thumbnail

The Universal Law of Gravitation - Part 1 | Physics | Don't Memorise

This video explains the concept of the Universal Law of Gravitation. To learn more about Gravitation, enroll in our full course now: https://infinitylearn.com/microcourses?utm_source=youtube&utm_medium=Soical&utm_campaign=DM&utm_content=c9shwPMpSq8&utm_term=%7Bkeyword%7D To watch the se

From playlist Physics

Video thumbnail

The Normal Distribution (1 of 3: Introductory definition)

More resources available at www.misterwootube.com

From playlist The Normal Distribution

Video thumbnail

Wissenschaftsfreiheit – Prof. Ulrich Becker – 70 Jahre Grundgesetz

Prof. Dr. Ulrich Becker, Direktor am Max-Planck-Institut für Sozialrecht und Sozialpolitik, erläuterte im Forum „70 Jahre Grundgesetz: Wissenschaftsfreiheit in Gefahr?“ die Regelung der Wissenschaftsfreiheit im Grundgesetz, historische und europäische Hintergründe, ging aber auch auf poten

From playlist Videos auf Deutsch

Video thumbnail

Jordan-Normalform Teil 2

Abonniert den Kanal oder unterstützt ihn auf Steady: https://steadyhq.com/en/brightsideofmaths Ihr werdet direkt informiert, wenn ich einen Livestream anbiete. Hier erzähle ich etwas über die Jordan-Zerlegung von quadratischen Matrizen bzw. die jordansche Normalform an einem Beispiel. (

From playlist Lineare Algebra

Video thumbnail

Physics - E&M: Maxwell's Equations (9 of 30) Differential Form of Gauss' Law: 1

Visit http://ilectureonline.com for more math and science lectures! In this video I will explain Gauss' Law in differential form.

From playlist PHYSICS 46 MAXWELL'S EQUATIONS

Video thumbnail

Riemann-Integral Definition

Abonniert den Kanal oder unterstützt ihn auf Steady: https://steadyhq.com/en/brightsideofmaths Ihr werdet direkt informiert, wenn ich einen Livestream anbiete. Hier erkläre ich kurz das Riemann-Integral mit Ober- und Untersumme. Die Definition ist übliche, die im 1. Semester eingeführt w

From playlist Analysis

Video thumbnail

What is Normalization in SQL? | Database Normalization Forms - 1NF, 2NF, 3NF, BCNF | Edureka

🔥 MySQL DBA Certification Training: https://www.edureka.co/mysql-dba This Edureka video on 'What is Normalization' will help you understand the basic concepts of Normalization in SQL and Databases and how it helps in organizing data and data redundancy in SQL with examples. Below are the

From playlist MySQL Tutorial For Beginners | Edureka

Video thumbnail

UHCL 28a Graduate Database Course - First and Second Normal Forms

This video corresponds to the unit 6 notes for a graduate database (dbms) course taught by Dr. Gary D. Boetticher at the University of Houston - Clear Lake (UHCL). The theme is relational database theory. This video focuses on the definition of first and second normal forms. Also, it expla

From playlist UHCL Graduate Database Course

Video thumbnail

Relational Databases (part 3 of 6)

The essential concepts of relational databases. Part of a larger series teaching programming. Visit codeschool.org

From playlist Relational Databases

Video thumbnail

Lecture 13: Smooth Surfaces II (Discrete Differential Geometry)

Full playlist: https://www.youtube.com/playlist?list=PL9_jI1bdZmz0hIrNCMQW1YmZysAiIYSSS For more information see http://geometry.cs.cmu.edu/ddg

From playlist Discrete Differential Geometry - CMU 15-458/858

Video thumbnail

Lec 20 | MIT RES.6-008 Digital Signal Processing, 1975

Lecture 20: Computation of the discrete Fourier transform, part 3 Instructor: Alan V. Oppenheim View the complete course: http://ocw.mit.edu/RES.6-008 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu

From playlist MIT RES.6-008 Digital Signal Processing, 1975

Video thumbnail

Database Normalisation: Third Normal Form

This video is part of a series about database normalisation. It explains how to transform a database, which is already in second normal form, into third normal form by working through an example. It covers the criteria for the second normal form including ensuring that a relation does no

From playlist Database Normalisation

Video thumbnail

Equation of plane: Point-Normal form

How to derive the point-normal equation of a plane. The ideas rely on the dot product. Free ebook https://bookboon.com/en/introduction-to-vectors-ebook (updated link)

From playlist Introduction to Vectors

Video thumbnail

UHCL 29a Graduate Database Course - Third Normal Form and Database Design Shortcuts

This video corresponds to the unit 6 notes for a graduate database (dbms) course taught by Dr. Gary D. Boetticher at the University of Houston - Clear Lake (UHCL). The theme is relational database theory. This video focuses on the definition of third normal form. It also provides several s

From playlist UHCL Graduate Database Course

Video thumbnail

Gravitation (1 of 17) Newton's Law of Universal Gravitation, An Explanation with Examples

This video goes over an explanation of Newton's Universal Law of Gravitation. Also included are two examples of how to calculate the force of attraction between two objects that have mass. This is know as an inverse square law. The force of attraction between two objects is directly propor

From playlist Gravitation: Orbital Velocity, Orbital Period, Potential Energy, Kinetic Energy, Mass and Weight

Related pages

Pushdown automaton | Production (computer science) | Chomsky normal form | Context-free language | Kuroda normal form | Formal language | Left recursion | Top-down parsing | Context-free grammar | Backus–Naur form