JESS Java Expert System Shell

1
JESSJava Expert System Shell

• Richard Pruitt
• CAP5605
• Dr. Lacher
• 12.07.05

2
Setup

• http//herzberg.ca.sandia.gov/jess/
• Version 7.0b4
• JDK 1.4
• License
• Government Agencies Unrestricted License
• Academia Restricted License
• Commercial Purchase License

3
Jess

• Written by Ernest Friedman-Hill
• 1995
• Sandia National Laboratories in Livermore, CA
• Latest Version has a new Eclipse Plug-in and Rete
  Diagram View

4
Jess

• Rete Algorithm to process rules
• Rete is a an efficient mechanism for solving the
  difficult many-to-many matching problem by
  remembering results
• Forward and Backward Chaining
• Working memory queries
• Directly manipulate and reason about Java objects
• You can create Java objects, call Java methods,
  and implement Java interfaces without compiling
  any Java code.

5
How it Works

• Production System
• Production Rules
• Added with (defrule)
• Working Memory
• Shown by running (facts)
• Recognize-Act Cycle
• Started by running (run)
• Forward-Chaining by default
• Can do backward-chaining
• (do-backward-chaining)

6
Animal Identification

• Created an animal identification system.
• System will ask questions trying to narrow down
  which animal it is.
• Animals (16)
• Snake
• Cat
• Dog
• Shark
• Whale
• Kola
• Panther

7
Syntax

• Define Rules
• (defrule purr (warmblood y)(water n)
• gt (printout t "Does it purr? (y or n)")
  (assert (purr (read))))
• Rule is fired if meets conditions on the left
  side
• warmblooded y
• water n
• Executes RHS when fired
• (printout t "Does it purr? (y or n)") (assert
  (purr (read)))

8
Syntax

• Not
• (not (warmblood n))
• OR
• (warmblood yn)
• (or (furry n) (trees y))

9
Functions

• (deffunction max (?a ?b)
• (if (gt ?a ?b) then (return ?a)
• else (return ?b)))

10
Rules

• Questions
• (defrule warmblood
• (start y) gt (assert (warmblood
  (ask-question-yn "Is it warmblooded?"))))
• (defrule water
• (warmblood yn) gt (assert (water
  (ask-question-yn "Does it live in the
  water?"))))
• (defrule carnivore
• (warmblood yn)(water yn)
• gt (bind ?ans (ask-question-yn "Is it a
  carnivore?"))
• (assert (carnivore ?ans))
• (assert (herbivore (neg-yn ?ans))))
• (defrule herbivore
• (warmblood yn)(water yn)
• gt (bind ?ans (ask-question-yn "Is it a
  herbivore?"))
• (assert (herbivore ?ans))
• (assert (carnivore (neg-yn ?ans))))

11
Rules

• Answers
• (defrule snake (warmblood n)(slither y)(water
  yn)
• gt (assert (answer snake)))
• (defrule cat (warmblood y)(purr y)(trees n)
• gt (assert (answer cat)))
• (defrule dog (warmblood y)(bark y)
• gt (assert (answer dog)))
• (defrule shark (warmblood n)(carnivore y)(water
  y)
• gt (assert (answer shark)))

12
Demos

• (batch animals.clp)
• (batch jframe.clp)