Information Technology Reference
In-Depth Information
Solution), the reasoning occurs by applying the knowledge from the Knowledge database to
the evidence.
Model building
(data mining)
Inferencing (using
knowledgebase and
evidence theory)
Stage 1
Stage 2
HasLungCancer(positive x-ray, 0.028)
HasLungCancer(smoker,
positive x-ray, 0.274)
evidence
Solution
Raw data
Knowledge database
Intelligent system
Fig. 4. Abstract view on computer reasoning
One of the important components in Figure 4 is evidence. In computer reasoning, evidence
is the main factor that influences a computer's judgment. One of the important
characteristics of evidence is its quality. In this abstract view, reasoning is persuaded by the
presence of evidence. For example, without any evidence, our view of the initial world
about the probability of a person with lung cancer is 0.2%, with the presence of first piece of
evidence, the positive result of x-ray test, our view of the modified world about the
probability of a person with lung cancer is 2.8%, with the presence of two pieces of evidence,
the positive result of x-ray and the positive result of CT scan, our view of the new world
about the probability of a person with lung cancer is changed again to 96%.
6.1 The properties and the definition of evidence (or a test)
The main role of a piece of evidence is its influence on a rational mind. To see how this
influence is realized, we need to investigate the properties about evidence. In this section,
we will give definition of evidence; and will describe properties of evidence. These
definition and properties are given in the following highlight box.
