SRKR Engineering College
Department of Computer Science and
Engineering, Bhimavaram, A.P. - 534204
FORMAL LANGUAGES & AUTOMATA THEORY
Outcomes
The student will be able to
 Understand the Central Concepts of Automata Theory and
Finite Automation
 Explain the Acceptance of a String by a Finite Automation
Finite Automata Example
Push
 Switch
Start
Off
On
Push
Central Concepts of Automata



Languages: “A language is a
collection of sentences of finite
length all constructed from a finite
alphabet of symbols”
Grammars: “A grammar can be
regarded as a device that
enumerates the sentences of a
language” - nothing more,
nothing less
N. Chomsky, Information and
Control, Vol 2, 1959
8 75
Important Definitions
 Alphabets
 An Alphabet is a finite, non empty set of symbols.
 Symbolized by ∑
 ∑ = {0,1}
 ∑ = {a,b,…….z}
 Strings
 A String is a finite sequence of symbols chosen from some
alphabet
 0111, 110
 cse, suresh, aaabb
Important Definitions
€
Length of a String
 |w|
Powers of an Alphabet  ∑k ∑*
Concatenation of Strings  xy
Languages
 Empty String




 A set of strings all of which are chosen from some , where ∑ is
a particular alphabet.  L
Examples of Languages
 L of all strings consisting of n 0s followed by n 1s, for n>=0
 Set of strings of 0s and 1s with an equal number of each
 Set of binary numbers whose value is a prime
FINITE AUTOMATA
i) Input Tape
ii) Finite Control
iii) Read head
Acceptance of a string by FA
A finite automaton M is a 5- tuple (Q, Σ, δ, q0, F) consisting of finite
set of states (Q), finite set of input symbols (Σ), transition function (δ)
start state (q0∈ Q) and set of accept states (F)