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Category Archives: Theory of Computation

Before reading this article, we recommend you to first read about Pushdown Automata and Context Free Languages.   Suppose we have a context free grammar… Read More
Recursive Enumerable (RE) or Type -0 Language RE languages or type-0 languages are generated by type-0 grammars. An RE language can be accepted or recognized… Read More
DFA minimization stands for converting a given DFA to its equivalent DFA with minimum number of states. DFA minimization is also called as Optimization of DFA… Read More
An NFA can have zero, one or more than one move from a given state on a given input symbol. An NFA can also have… Read More
Context Free Languages (CFLs) are accepted by pushdown automata. Context free languages can be generated by context free grammars, which have productions (substitution rules) of… Read More
We have already discussed finite automata. But finite automata can be used to accept only regular languages. Pushdown Automata is a finite automata with extra memory… Read More
As discussed in Chomsky Hierarchy, Regular Languages are the most restricted types of languages and are accepted by finite automata.   Regular Expressions Regular Expressions… Read More
In this article, we will see some popular regular expressions and how we can convert them to finite automata. Even number of a’s : The… Read More
There are two Pumping Lemmas, which are defined for 1. Regular Languages, and 2. Context – Free Languages   Pumping Lemma for Regular Languages For any… Read More
See Last Minute Notes on all subjects here. We will discuss the important key points useful for GATE exams in summarized form. For details you… Read More
According to Chomsky hierarchy, grammar is divided into 4 types as follows:  Type 0 is known as unrestricted grammar. Type 1 is known as context-sensitive… Read More
Finite Automata(FA) is the simplest machine to recognize patterns. The finite automata or finite state machine is an abstract machine that has five elements or… Read More
Given the language L = {ab, aa, baa}, which of the following strings are in L*? (A) abaabaaabaa (B) aaaabaaaa (C) baaaaabaaaab (D)  baaaaabaa Answer:… Read More
What is the complement of the language accepted by the NFA shown below? (A) A (B) B (C) C (D) D Answer: (B) Explanation: The… Read More