1. Principles of Computing – UFCFA3-30-1
Week-7
Pushdown Automata (Continue…)
Instructor : Mazhar H Malik
Global College of Engineering and Technology

2. Pushdown automata

3. FINITE AUTOMATA PUSHDOWN AUTOMATA
Difference Between Finite Automata and Push down Automata
FINITE AUTOMATA
PUSHDOWN AUTOMATA
A finite automaton (FA) is a simple idealized machine used to recognize patterns within input taken from some character set
A pushdown automaton (PDA) is a type of automaton that employs a stack.
It doesn’t has the capability to store long sequence of input alphabets
It has stack to store the input alphabets
Input alphabets are accepted by reaching “final states”
Input alphabets are accepted by reaching :
1.     Empty stack
2.     Final state
NFA can be converted into equivalent DFA
NPDA has more capability than DPDA
It consist of 5 tuples:
L = {Q, q0, ∑, F, σ}
It consists of 7 tuples:
L = {Q, q0, ∑, F, ᴦ, σ, z0  }
Finite automata can be constructed for regular language
Pushdown automata can be constructed for context free grammar