1 Basic Foundations

Theory of Computation · Unit 1 · 3 hrs

Basic Foundations

Exam-focused notes for Basic Foundations (Theory of Computation, CSC262): what the TU syllabus asks and how it has actually been tested, with 4 solved past questions from this unit.

What this unit covers

  • Review of Set Theory
  • Logic
  • Functions
  • Proofs
  • Automata, Computability and Complexity
  • Complexity Theory
  • Computability Theory
  • Automata Theory
  • Basic concepts of Automata Theory
  • Alphabets
  • Power of Alphabet
  • Kleen Closure Alphabet
  • Positive Closure of Alphabet
  • Strings
  • Empty String
  • Substring of a string
  • Concatenation of strings
  • Languages
  • Empty Language

Positive Closure of Alphabet

20815 marks

Does machine always refer to hardware? Justify. Define positive closure and Kleene closure. [5]

--- No, a machine does not always refer to hardware. In the context of Theory of Computation (TOC), the term "machine" refers to an abstract model rather than a physical hardware device. Abstract Model: An abstract model of a computer system is considered e...

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2080.15 marks

Differentiate Kleen closure from positive closure. Compute positive and Kleen closure of {ab}. [5]

- Set: $\{ab\}$ (a set containing a single element, the string "ab") - Required: differentiate Kleene closure from positive closure; compute both for $\{ab\}$. Property Kleene Closure ($L^$) Positive Closure ($L^+$) --------- Definition All strings formed b...

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Strings

20805 marks

Define string, substring, empty string, and empty language over alphabet {a,b}. [5]

A string (also called a word) is a finite sequence of symbols taken from an alphabet. Over the alphabet Σ = {a, b}, a string is any finite arrangement of the symbols a and b. Examples over {a, b}: - a - b - ab - aab - bba - abab Formally, if Σ = {a, b}, the...

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Alphabets

20785 marks

Define the term alphabet, prefix and suffix of string, concatenation and Kleen closure with example. [5]

--- An alphabet is a finite, non-empty collection (set) of symbols. It is usually denoted by Σ. Example: - Σ = {a, b, c} - Σ = {0, 1} --- A string p is called a prefix of a string w if it is obtained by removing zero or more trailing symbols of w. Example: ...

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