Date post: | 18-Jul-2015 |
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Engineering |
Upload: | gaurav-sinha |
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ObjectivesWhat is Automata or Automation
Theory?
How could we find output of Finite
Automata?
The Moore machine
The Mealy machine
What is Automata or Automation Theory?
• Automata Theory is the study of “Abstract machines” or It is the study of “Self-Operating virtual machines” to help in logical understanding of how input and output process in computationproblems. Automata comes from Greek word means “Self-Acting”.
• Automata are used in the field of Artificial Intelligence, computational theory, compiler design, parsing, etc.
• An Automation is supposed to run in some given sequence of inputs in Discrete time steps.
• The Automation consists of states(represents by circles) and transitions(represent by arrows)
• An Automation contains finite number of states, as in above figure you can see S1 and S2 are two states.
• Transition of input is shown by arrow from one states to another.
• At each time step when the automation reads a symbol, it jumps or transitions to another state .
• Once all inputs has been read, the automation said to have stopped and that state is called final state.
Mathematical Representation of Finite Automation
• A deterministic finite automation is represented by a 5-tuple(Q, Σ,δ,q0,F).
• Where, Q is a finite set of states.
• Σ=finite set of symbols, called alphabets of Automation.
• δ=transition function, δ: Q* Σ Q.
• q0= start state before input is processed
• F=set of states of Q called accept states.
How could we find output of Finite Automata?
• There are two different Models to find out the output of finite-state machine
• Firstly, When output values are determined by its current state, i.e., with the help of Moore machine models.
• Secondly, when output values are determined both by its current state and by the value of its inputs, which is represented by Mealy machine model.
Moore Machine:• A Moore Machine is based on Sequential
Machines. Mathematically it can be defined using a 6-tuple (S, S0, I, Δ, δ, λ), where:
• S=Finite set of states.• S0=Start or called as Initial state.• I = Finite Set of Input Alphabet.• Δ= Finite Set of Output Alphabet.• δ = Transition function from I*S into S.• λ = Output function mapping S into Δ.Application : It is used in Edge detector, Binary
Adding machine, Clocked Sequential System, LED’s, etc.
Visual Representation:
Table
State transition table is a table showing relation between an input and a state. We can make the table of any diagram
and we can easily find out the output of finite state machine.
States a b Output
q0 q1 q2 1
q1 q1 q1 0
q2 q1 q0 1
Mealy Machine• Machine is a Six tuple(S, I, Δ, δ, λ’, S0),
where:
• S=Finite set of States.
• I = Input alphabet.
• Δ = Output alphabet.
• δ = Transition function I * S into S
• λ'= Output function mapping S into Δ.
• S0 = Initial state.
Application of Mealy Machine: Traffic lights, Bar Code Scanner, Gas Pump, Vending machine, etc.
--------------------------------
• Simple Mealy Machine Diagram:
State Diagram for a simple Mealy Machine with one Input and one Output.
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Si
S1
S0
SummaryBoth Moore and Mealy Machines
are used in the field of Technology. There is subtle
difference in the behaviour of a Mealy and Moore machine. Both are used to implement Simple as
well as Complex Problem of Computation in our daily life, like in
Computer, Traffic lights, LED’s, Electronic Circuits, etc.