Introduction to Theory of Automata By: Wasim Ahmad Khan

What do you think about it ???  Automata?  Language?  Relation between Language and Machine?

What does “Theory of Automata” mean? The word “Theory” means that this subject is a more mathematical subject and less practical. Foundation for practical subject. Focuses on theoretical aspects of Computer Science.

Automata It is plural of Greek word Automaton, which means Machine in English. Hence, Automata means Machines.

Language Language is nothing except the collection of Rules.

Relation between Machine & Language As all of you know that to instruct any machine you need to know its language. Similarly, if you know a language that language is of no use unless you have a machine which can understand that language. So : Language and machine both are inter-related. One is useless in the absence of other.

Parts of the Language Alphabet/Symbol A finite non-empty set of specific symbols (letters), is called alphabet. It is denoted by Greek letter ∑ (Sigma). Word Specific letters in specific quantity and in Specific order. Sentence Specific words in specific quantity and in Specific order.

How to study language? There are two parts of study of a language 1. Structure/Syntax Its study includes how the correct words/sentences are formed. ( No syntax errors ) 2. Meaning/Semantics its study includes how to decide that a structurally correct formed word/sentence has a correct meaning associated or not. ( No Semantical errors )

Types of Language There are many types of languages but we have experience of using two types of languages:  Formal Languages ( Java/C++/Perl/C/ …)  Natural Languages (English/Hindi/Arabic/ …)

Formal Languages Formal means to study about form / structure /shape ; Meaning is out of Scope of our study of formal languages. For example: She is a boy. This sentence is structure wise correct but meaning wise incorrect. In formal languages it is correct but incorrect in Natural language English.