Every regular expression describes regular language Automata Theory by ComputeNow - July 27, 2019July 27, 20190 Every regular expression describes regular language, let R be an arbitrary regular expression over the alphabet Σ. We will prove that the language described by R is a regular language. The proof is by induction on the structure of R. The first base case of induction: Assume that R = ε. The R describes the language of {ε}. In order
Regular Language in Automata Thoery Automata Theory by ComputeNow - September 20, 2018September 18, 20180 Regular Languages or Formal Language : A language is regular if it can be expressed in terms of regular expression. Closure Properties of Regular Languages Union : If L1 and If L2 are two regular languages, their union L1 ∪ L2 will also be regular. For example, L1 = {an | n ≥ 0} and
What is Chomsky Hierarchy in Theory of Computation Automata Theory by ComputeNow - September 19, 2018September 19, 20180 What is Chomsky Hierarchy? Noam Chomsky categorised regular and other languages which called as Chomsky Hierarchy. Language Class Grammar Automaton 3 Regular NFA or DFA 2 Context-Free Push-Down Automaton 1 Context-Sensitive Linear-Bounded Automaton 0 Unrestricted (or Free) Turing Machine This is a hierarchy, so every language of type 3 is also of types 2, 1 and 0; every language of type 2 is also of types 1 and 0
Regular Expression Using Perl Perl Script Languages by ComputeNow - September 3, 2018September 3, 20180 Regular Expression Using Perl : Perl is the language that is the most famous for its use of regular expression for good reasons. We use the =~ operator to denote a match or an assignment depending upon the context. The use of !~ is to reverse the sense of the match. There are basically two regex operators
Context Free Grammars Automata Theory by ComputeNow - August 23, 2018August 23, 20180 Context free grammars (CFGs) are used to describe context-free languages. A context-free grammar is a set of recursive rules used to generate patterns of strings. A context-free grammar can describe all regular languages and more, but they cannot describe all possible languages. Context-free grammars are studied in fields of theoretical computer science, compiler design, and linguistics. CFG’s are
