Turing Machine Simulator

A simple simulator of the unary mathematical model of a Turing Machine, as studied at ESI Algiers. This project is designed for educational purposes, helping students visualize and understand how a Turing Machine operates step by step.

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Overview

The simulator implements a unary representation of natural numbers and executes algorithms defined as formal Turing Machine instructions. It provides a visual tape, a reading head, and an execution environment similar to a small IDE.

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How It Works

The Tape

• The tape is initially filled with 0s, which represent blanks.
• The reading head starts at a fixed position and always reads the highlighted cell.

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Number Representation (Unary)

• The machine works only with natural numbers (including 0).
• A number n is represented using n + 1 bars (|).

Examples:

• 0 → |
• 2 → |||
• 5 → ||||||

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Arguments Encoding

• Multiple arguments are separated using an asterisk (*).

Examples:

• (2, 3) → |||*||||
• (1, 0, 2) → ||*|*|||

!! No spaces are allowed between symbols.

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Instructions Format

Each instruction of the algorithm must follow this exact format:

<current_state>,<read_value>,<action_to_take>,<next_state>

Instruction Fields

1️ <current_state>

• The current state of the machine.

2️ <read_value>

• The symbol currently read by the head (0, |, or *).

3️ <action_to_take>

The action can be either a move or a write:

Move actions:

• R → move one cell to the right
• L → move one cell to the left

Write actions:

• 0 → write a blank
• | → write a bar
• * → write an asterisk

!! If the machine encounters a state/read-value combination with no defined instruction, the simulator will throw a runtime error.

4️ <next_state>

• The state to transition to after executing the action.

Two cases:

• Defined next state → execution continues.
• Undefined next state → the program halts, marking the end of execution.

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Halting the Machine

• You can manually stop execution at any time using the red “Halt” button in the interface.

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Interface Notes

• On the right side of the screen, below the IDE, you will find a set of remarks.
• These notes provide helpful guidance for using the simulator.
• A full and detailed documentation will be uploaded in the future and will replace these remarks.

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Purpose

This simulator is intended to:

• Help students understand formal Turing Machine execution
• Visualize tape manipulation and state transitions
• Experiment with unary algorithms in a controlled environment

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Future Work

• Full documentation
• Example programs (addition, subtraction, comparison, etc.)
• Improved error messages
• Export / import of machine definitions

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