Finite State Machine Applications

Eric Gribkoff

May 29, 2013

Outline

1 Applications of Finite State Machines

2 Vending Machine

3 Pac-Man

4 TCP

5 Adding Output

Eric Gribkoff | UC Davis 2/11

1 Applications of Finite State Machines• Vending Machines

• Traffic Lights

• Video Games

• Text Parsing

• CPU Controllers

• Protocol Analysis

• Natural Language Processing

• Speech Recognition

Eric Gribkoff | UC Davis 3/11

Eric Gribkoff | UC Davis 4/11

2 Vending Machine

$0.00start $0.25 $0.50 $0.75

$1.00 $1.25 $1.50 $1.75

$2.00

$0.25 $0.25 $0.25

$0.25

$0.25

$1.00 $1.00 $1.00 $1.00

$1.00

select select select select

select

$0.25, $1.00 $0.25, $1.00 $0.25, $1.00

$0.25, $1.00

select select select

select

Eric Gribkoff | UC Davis 5/11

3 Pac-Man

Eric Gribkoff | UC Davis 6/11

Wander the Mazestart Chase Pac-Man

Return to Base Flee Pac-Man

SpotPac-Man

LosePac-Man

Pac-Man EatsPower Pellet

Power PelletExpires

Pac-Man EatsPower Pellet

Eaten byPac-Man

ReachCentral Base

Figure 1: Behavior of a Pac-Man Ghost

Eric Gribkoff | UC Davis 7/11

4 TCP

Eric Gribkoff | UC Davis 8/11

CLOSEDstart

LISTEN

SYN_SENTSYN_RCVD

ESTABLISHED

FIN_WAIT_1

FIN_WAIT_2

CLOSE_WAIT

CLOSINGLAST_ACK

TIME_WAIT

Passive open Close

SYN/SYN + ACK Send/SYN

Timeout/RSTClose

Active open/SYN

SYN/SYN + ACK

Close/FIN

ACK SYN + ACK/ACK

Close/FIN FIN/ACK

ACK

ACK

FIN +ACK/ACK

FIN/ACK

ACK

Close/FIN

ACK

Timeout after two maximumsegment lifetimes (2*MSL)

Figure 2: TCP State Diagram

Eric Gribkoff | UC Davis 9/11

5 Adding Output

Finite state machines with an output tape are known as finite statetransducers (FST). A Mealy machine is an example of a deterministic FST.

Instead of accepting or rejecting strings, a Mealy machine maps inputsequences to output sequences.

Eric Gribkoff | UC Davis 10/11

Next: Finite State Transducers