Palindrome Program on Turing Machine

Understand and run Palindrome validation program on Turing Machine Simulator

92 Participants 30 Minutes Beginner

A Turing machine is a theoretical computational device that was introduced by the British mathematician and logician Alan Turing in 1936. It serves as a fundamental model of computation and has played a pivotal role in the development of computer science and the theory of computation. Turing machines are composed of a tape, a tape head, and a finite set of states. They are capable of simulating the logic of any computer algorithm, given enough time and memory.



How Turing Machines Work

Turing machines operate on an infinite tape divided into cells, each of which can hold a symbol from a finite alphabet. The tape head is positioned over one cell at a time and can read the symbol on the current cell, write a symbol on it, or move one step to the left or right. The machine transitions between states based on its current state and the symbol it reads from the tape. This progression persists until the machine reaches a halting state, at which juncture the procedure comes to an end.


Use of Turing Machines

Turing machines are a theoretical concept and are not meant to be physically built. Instead, they serve as a foundational concept in computer science and mathematics to reason about computability and the limits of computation. They are used to study the solvability of problems, define algorithms, and prove theorems about what can and cannot be computed.


What is the Palindrome Problem?

The palindrome problem is a classic example in computer science and mathematics. A palindrome is a sequence of characters that reads the same forwards as it does backward. For example, "1001" and "110011" are palindromes. The palindrome problem determines whether a given input binary string is a palindrome or not.


Palindrome Binary Turing Machine Program

To illustrate how a Turing machine can solve the palindrome problem, let's create a simplified Turing machine program in binary.

Turing Machine Description:

  • Alphabet: {0, 1, _} (0 and 1 are binary symbols, B is the blank symbol)

  • States: {0,1i,1o,2i, 2o,3,4, accept,reject} {accept and reject are the accepting and rejecting states)

  • Initial State: 0

  • Transition Function: A set of rules that define how the machine moves between states based on the symbols it reads and writes.

Logic of the Palindrome Turing Machine:

  • Start in state 0.

  • In state 0, move right until a blank symbol (_) is encountered, replacing each 0 and 1 with _.

  • When a blank is encountered, transition to states 1i,1o.

  • In state 1i,1o, move left until a non-blank symbol is encountered.

  • Compare the leftmost and rightmost symbols:

  • If they are the same (both 0 or both 1), replace them with _ and move back to state 0.

  • If they are different, move to state accept (if the entire string has been checked and found to be a palindrome) or state reject (if the symbols don't match).

  • Repeat steps 2-5 until you reach the accepting (accept) or rejecting (reject) state.

This revised version aligns the steps with the state numbering you provided for the Palindrome Turing Machine.


Refer to these links to learn more

1. Turing Machine in TOC - GeeksforGeeks



Turing machines are powerful theoretical constructs used to explore the limits of computation and to solve computational problems. The palindrome problem serves as a quintessential demonstration of a task that a Turing machine can successfully address. Through a series of predefined rules and state transitions, a Turing machine can ascertain whether a provided input string possesses palindrome characteristics. This instance underscores the adaptability and computational prowess inherent in Turing machines, reaffirming their enduring significance as a foundational concept in theoretical computer science.

Turing Machine Program


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