Transcript Case-Based Reasoning

Case-Based Reasoning
Case-Based Reasoning (CBR)
• Case-based reasoning (CBR)
A methodology in which knowledge and
/or inferences are derived from historical
cases
• Definition and concepts of cases in CB
R
– Stories
Cases with rich information and episodes. Le
ssons may be derived from this kind of case
s in a case base
Case-Based Reasoning (CBR)
• Advantages of using CBR
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Knowledge acquisition is improved.
System development time is faster
Existing data and knowledge are leveraged
Complete formalized domain knowledge is not requi
red
Experts feel better discussing concrete cases
Explanation becomes easier
Acquisition of new cases is easy
Learning can occur from both successes and failures
Case-Based Reasoning (CBR)
CBR Logic
Case-based reasoning is a problem solving
paradigm that in many respects is
fundamentally different from other major AI
approaches. Instead of relying solely on
general knowledge of a problem domain, or
making associations along generalized
relationships between problem descriptors
and conclusions, CBR is able to utilize the
specific knowledge of previously
experienced, concrete problem situations
(cases).
A new problem is solved by finding a
similar past case, and reusing it in the new
problem situation.
A second important difference is that CBR
also is an approach to incremental,
sustained learning, since a new experience
is retained each time a problem has been
solved, making it immediately available for
future problems.
The CBR field has grown rapidly over the
last few years, as seen by its increased
share of papers at major conferences,
available commercial tools, and successful
applications in daily use.
4 step processes in CBR
1. Retrieve: Given a target problem, retrieve
from memory cases relevant to solving it. A
case consists of a problem, its solution, and,
typically, annotations about how the
solution was derived.
For example, suppose Fred wants to
prepare blueberry pancakes. Being a novice
cook, the most relevant experience he can
recall is one in which he successfully made
plain pancakes. The procedure he followed
for making the plain pancakes, together
with justifications for decisions made along
the way, constitutes Fred's retrieved case.
2. Reuse: Map the solution from the previous case
to the target problem. This may involve adapting
the solution as needed to fit the new situation. In
the pancake example, Fred must adapt his
retrieved solution to include the addition of
blueberries.
3. Revise: Having mapped the previous solution to
the target situation, test the new solution in the
real world (or a simulation) and, if necessary,
revise. Suppose Fred adapted his pancake
solution by adding blueberries to the batter. After
mixing, he discovers that the batter has turned
blue – an undesired effect. This suggests the
following revision: delay the addition of
blueberries until after the batter has been ladled
into the pan.
4. Retain: After the solution has been
successfully adapted to the target
problem, store the resulting experience
as a new case in memory. Fred,
accordingly, records his new-found
procedure for making blueberry
pancakes, thereby enriching his set of
stored experiences, and better preparing
him for future pancake-making demands.
Comparison to other methods
At first glance, CBR may seem similar to
the rule induction algorithms of machine
learning. Like a rule-induction algorithm,
CBR starts with a set of cases or training
examples; it forms generalizations of
these examples, albeit implicit ones, by
identifying commonalities between a
retrieved case and the target problem.
Examples of CBR system
• SMART: Support management automated
reasoning technology for Compaq customer
service
• CoolAir: HVAC specification and pricing system
• Vidur - A CBR based intelligent advisory system,
by C-DAC Mumbai, for farmers of North-East
India.
• jCOLIBRI - A CBR framework that can be used to
build other custom user-defined CBR systems.
• CAKE - Collaborative Agile Knowledge Engine.
• Edge Platform - Applies CBR to the healthcare,
oil & gas and financial services sectors.