Tuesday, 31 May 2011

Acceptance of strings and Languages



The string and languages can be accepted by finite automata, when it reached to a finite state. There are two preferred notations for describing automata:
   Transition diagram;
A transition diagram or transition graph can be defined as collection of-
1.      Finite set of states Q
2.      Finite set of symbols∑.
3.      A non empty set S of Q. it is called start state.
4.      A set F subset of Q of final states
5.      A transition  function Q x A-> Q with as state and A as input from ∑*.
The notations used in transition diagram are-

Example:
The FA can be represented a using transition graph. The machine initially is in start state q0 then on receiving input 0 it changes to state q1. From q1 \receiving input 1the machine changes its state to q4. The state q4 is a final state or accept state. When we trace the input for transition diagram and reach to a final state at end of input string then it is said that the given input is accepted by transition diagram.
Transition Table:
This is a tabular representation of finite automata. For transition table the transition function is used.
              Input
state
0
1
q0
q1
q2
q1
-
q4
q2
q3
-
q3
q4
-
q4
-
-

The rows of the table correspond to states and columns of the table corresponding to inputs.

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