Production System

1
Production System

• Production rule
• AI Planning, expert systems, action selection
• Condition/Action
• LHS/RHS
• Match/Choose/Act
• Inference engine
• OPS5

2
Production System

• Matching
• Expressive power
• RETE (Forgy 1983, OPS5)
• Variables
• Substitution of constants
• Conflict Set
• Conflict Resolution
• All productions that match
• Utility, first, priority

3
Production System Cycle

• Match conditions of all rules to buffers
• Those that match enter the conflict set
• Conflict resolution selects a rule to fire
• Action side of rule initiates changes to one or
  more buffers
• If no production can match and no action is in
  progress then quit else repeat

4
ACT-R

• Architecture Knowledge gt Behavior
• Procedural versus Declarative Knowledge
• Declarative
• Aware of
• Can describe to others
• Facts
• Structures called Chunks
• Procedural
• Display in behavior
• Not conscious of
• e.g. language
• rules

5
Declarative Knowledge

• Chunk - basic unit of declarative knowledge
• Type slots
• Type - category (bird)
• Slots - attributes (color, size)

6
Chunks

• Types
• Categories
• Names
• Reference
• Not part of chunk

7
Creating Chunks
Chunk type ((chunk-type type-name slot-name1
(slot-namek init-val)..slot-namen)
(chunk-type count-order first second) (chunk-type
add arg1 arg2 sum count)
Chunk Instantiation (add-dm (chunk-name isa
type-name slot-name slot-value) )
(add-dm (a ISA count-order first 0 second 1)
(b ISA count-order first 1 second 2)
(second-goal ISA add arg1 5 arg2 2) ) sum and
count are nil
8
Procedural Knowledge

• Production Rule - basic unit of procedural
  knowledge
• Control
• IF the goal is to classify a person
• and he is unmarried
• THEN classify him as a bachelor

9
Production

• Condition-action pair
• If conditions are true then perform action
• Conditions
• Specification of chunks in buffers
• Actions
• Modification of buffers or module commands

10
ACT-R 6.0
ENVIRONMENT
11
ACT-R Production
12
Variables

• prefixed by sign, e.g. num
• Bind values to variables
• Two purposes
• Conditionals
• Compare values
• Test for non nil
• Copy values between slots
• Lhs -gt right hand side

13
Buffers

• Interface between procedural memory and other
  modules
• Implicit clearing
• Chunk creation
• Copies of chunks in Declarative Memory

14
Modules

• Procedural Module
• Choose next action
• Declarative Module
• Memory creation and retrieval
• Goal Module
• Task Control
• Imaginal Module
• Problem repesentation

15
Models

• Text file(s)
• Parameters
• Chunk-types
• Declarative Memory
• Productions
• Goal
• Must load

16
Environment

• (run-environment)
• (start-environment)
• Must load tcl\tk (Start Environment.exe or Start
  Environment OSX)
• (stop-environment)

17
Count Model
18
Pattern Matching Exercise
19
Addition Fact Example
ADDITION-FACT
3
7
VALUE
isa
VALUE
ADDEND1
SUM
FACT34
THREE
SEVEN
ADDEND2
4
isa
isa
FOUR
VALUE
isa
INTEGER
20
Addition Example
(CLEAR-ALL) (CHUNK-TYPE addition-fact addend1
addend2 sum) (CHUNK-TYPE integer value) (ADD-DM
(fact34 isa addition-fact addend1 three
addend2 four sum seven) (three isa
integer value 3) (four isa integer
value 4) (seven isa integer value 7)
21
Production Syntax
(P initialize-addition goalgt ISA
add arg1 num1 arg2
num2 sum nil gt goalgt
sum num1 count 0
retrievalgt isa count-order
first num1 )
(P increment-sum goalgt ISA add
sum sum count count
retrievalgt ISA count-order
first sum second newsum gt
goalgt sum newsum retrievalgt
isa count-order first
count )
22
(p got-number goalgt isa make-a-call
who person retrievalgt isa phone-number
who person where office
ph-num num gt !output! (The phone number
for person is num) goalgt
isa dial-number who person
ph-num num current-digit 1 )
(p dial-a-digit goalgt
isa dial-number ph-num num
current-digit digit state nil gt
!bind! d (get-digit digit num)
visual-locationgt isa visual-location
value d goalgt state dialing )
23
(P increment goalgt ISA
count-from start num1 - end
num1 step counting
retrievalgt ISA count-order
first num1 second num2 gt
goalgt start num2 retrievalgt
ISA count-order first
num2 !output! (num1) )
(p read-choose goalgt isa read-letters
state verify-choose visualgt isa text
value "choose" gt goalgt state
find-letter )
24
Models

• Count model
• Addition model
• Semantic model

25
Semantic Model
26
(P rotate-counter-clockwise goalgt ISA
translaterotate step
counter-clockwise reference-y y axis
axis form form
retrievalgt ISA point-i gt
screen-y (!eval! ( y 15)) gt !eval!
(rotate-counter-clockwise form axis) )
(P get-direction goalgt ISA
make-report step find-point
retrievalgt ISA point-i
screen-x x screen-y y gt
goalgt step find-direction
retrievalgt ISA direction lt
screen-x (!eval! ( x 15)) gt screen-x
(!eval! (- x 15)) lt screen-y (!eval! (
y 15)) gt screen-y (!eval! (- y 15)) )