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Category Archives: Theory of Computation & Automata

Given a string consisting of characters a and b, check if the string starts and ends with the same character or not. If it does,… Read More
Prerequisite: Deterministic Finite Automata Given a string, str consists of characters ‘a’ & ‘b’. The task is to check whether string str starts and ends with… Read More
Closure properties on regular languages are defined as certain operations on regular language which are guaranteed to produce regular language. Closure refers to some operation… Read More
Pushdown Automata: A Pushdown automata (PDA) is a finite state machine with an added stack storage. Additional stack is used in making the decision for transitions… Read More
Countable Set is a set having cardinality same as that of some subset of N the set of natural numbers . A countable set is… Read More
Prerequisite – Classification of Context Free Grammars, Ambiguity and Parsers Left Recursion: Grammar of the form, S --> S / a / b It is… Read More
Total Recursive Functions: A recursive function is called total recursive function if it is defined for its all arguments.Let f(a1, a2, …an) be a function defined… Read More
Prerequisite – Turing Machine  1. Multiple track Turing Machine:   A k-track Turing machine(for some k>0) has k-tracks and one R/W head that reads and writes… Read More
Problem – Implement a recognizer for pascal identifiers based on a DFA that accepts strings belonging to the definition of the language of the same.… Read More
This article tackles both theoretical and practical issues in Computer Science (CS). It reviews Turing Machines (TMs), a fundamental class of automata and presents a… Read More
Prerequisite: Finite Automata Introduction Problem-1: Construction of a minimal NFA accepting a set of strings over {a, b} in which each string of the language… Read More
Problem: Construct a deterministic finite automata (DFA) for accepting the language L = {w | w ∈ {a,b}* and Na(w) mod 3 = Nb (w)… Read More
Problem: Construct a DFA which accept the language L = {anbm | n > =1, (m) mod 3 = 1}. Explanation: For constructing the DFA,… Read More
Problem: Design a non deterministic PDA for accepting the language L = {wwR w ∈ (a, b)+}, i.e.,  L = {aa, bb, abba, aabbaa, abaaba,… Read More
The Gauss Seidel method is an iterative process to solve a square system of (multiple) linear equations. It is also prominently known as ‘Liebmann’ method.… Read More

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