Sherlock Holmes Goes Cyber

1
Sherlock Holmes Goes Cyber

• Eric Nelson
• Hemant Joshi
• Umit Topaloglu
• Advisor Dr. James Jones,
• Computer Science

2
Contents

• Story
• Current problem solving techniques
• Non-monotonic reasoning
• AnsProlog and Smodels
• 4 Incremental Executions
• Conclusion

3
Story

• Based on our expansion of Something Queer at the
  baseball park by Elizabeth Levy
• Jill, Ben, Gwen, and Marshall are at first
  practice
• Jill could not find her bat after practice
• Jill, Ben, Gwen, Marshall, Erica are at next
  practice
• Gwen could not find her glove after practice
• Later, Marshall got caught stealing the glove
• Who is likely the thief of bat?

4
Current problem solving techniques

• Conventional Languages
• C, Java programming, etc.
• Expert Systems, and Rule-Based Systems
• MYCIN Medical Expert System
• Knowledge Representation and Reasoning
• First Order Logic - Monotonic
• Decision Support Systems (???)
• Distributed Computing-shared knowledge

5
Non-monotonic reasoning

• human-like reasoning where conclusions are made
  with the available (often incomplete) knowledge
  and may be withdrawn in the presence of
  additional knowledge
• Smart systems of future cannot exist without
  this ability

6
AnsProlog and Smodels

• Declarative language paradigm far more powerful
  than procedural languages and object-oriented
  technologies
• Enables non-monotonic inferences
• Based on Answer set semantics, the most powerful,
  most well-researched logic programming semantics

7
Execution-1

• Situation
• Nothing is missing
• Result
• Nothing is missing, hence, no suspect

8
Execution-2

• Situation
• Jills bat is stolen
• Jill, Ben, Gwen, and Marshall present at practice
• Result
• Ben, Gwen, and Marshall are suspects, since they
  had opportunity

9
Execution-3

• Situation
• Gwens glove is stolen at second practice,
• Jill, Ben, Gwen, Marshall, and Erica present at
  practice
• Note Erica was missing at first practice, and
  present at second practice
• Result
• Everyone except Gwen is a suspect for stealing
  the glove
• Our previous suspects for stealing the bat remain
  the same

10
Execution-4

• Situation
• Marshall is caught stealing the glove
• Result
• The glove is no longer missing
• Marshall stole the glove
• Marshall is the only suspect for stealing the bat
• We can still introspect about our previous beliefs

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Conclusion

• Reason non-monotonically Ben and Gwen were
  previously thought to be primary suspects, are no
  longer primary suspects when Marshall is
  discovered stealing the bat
• More non-monotonic reasoning in the even that
  it is proven that Marshall did not steal the bat,
  then Ben and Gwen will again become suspects
• Ability to reason with respect to time
• Reasoning matches our intuition

12

• Questions ?