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# LectureNotes1 - ECS 120 Lesson 1 – Alphabets Languages...

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Unformatted text preview: ECS 120 Lesson 1 – Alphabets, Languages and Grammars, Pt. 1 Oliver Kreylos Friday, March 30th, 2001 1 Outline Today’s lesson will lay the foundations for all further material in this class. It will supply the definitions and techniques needed in the next couple of lessons to define a formal language – as opposed to a natural language like English – and introduce methods of defining specific languages. It will also reinforce the mathematical techniques of recursive definition and induction. 2 Alphabets An alphabet Σ = { s 1 , s 2 , . . . , s n } is a non-empty, finite set of symbols, also called characters . Examples: • The latin alphabet { a , b , . . . , z , A , B , . . . , Z } . • The greek alphabet { α, β, . . . , ω, A , B , . . . , Ω } . • The ASCII set. • The Unicode set. 3 Words A word x over an alphabet Σ is the concatenation of a finite number of symbols from Σ. In programming language terms, a word is a string of char- 1 acters. To handle words over an alphabet Σ mathematically, we recursivelyacters....
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LectureNotes1 - ECS 120 Lesson 1 – Alphabets Languages...

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