NonMonotonic Reasoning

1
Non-Monotonic Reasoning

• Non-monotonic reasoning involves a situation
  where a new conclusion might invalidate a
  previous conclusion
• Conversely, in a monotonic reasoning system
  conclusions are drawn sequentially without
  checking its effect on any previous conclusions.

2
Non-monotonic reasoning

• Therefore, following are the common situations
  for non-monotonic reasoning
• if a system has incomplete knowledge
• when solution criteria are continually changing
• when temporary assumptions may have to be made in
  complex problem-solving situations

3
Non-monotonic reasoning- examples

• An engineer discovers that a sub-system he has
  designed does not agree with another sub-system
  designed earlier in the process. The earlier
  sub-system, obviously, has to be
  modified/re-designed.

4
Non-monotonic reasoning- examples

• In any design situation, the designer has to
  start with a certain set of assumptions. These
  assumptions may lead to an unsatisfactory design
  when another iteration of the design process
  begins with a new set of assumptions. This
  continues until a satisfactory design is achieved.

5
Non-monotonic reasoning- examples

• Consider the following situation,
• I go to somebodys house with a bunch of flowers
  presuming that flowers are liked by most people.
  As soon as I enter the door, he starts sneezing
  heavily and I am forced to leave the flowers
  outside.

6
Solutions to Non-monotonic situations

• Dependency-directed backtracking
• (contrast with simple chronological
  backtracking)
• Truth-maintenance Systems
• Assumption-based truth-maintenance systems