Databases Reference
In-Depth Information
QUERY
INTERPRETATION:
Class Name A t t r i b u t e
Link Type Class
Name
Name
Instance
Atribute Value
Instance
EVALUATION:
?
G
{ M }
A
G
name
Inlet Needles
I
Manufacturer
X
X
name
I
X
A
Needles Seat
A
Figure 2.4:
Example of diagrammatic representation (based on
Mohan and Kashyap
,
1993
).
2.2
VISUAL INTERACTION
Visual Interaction refers to the kind of dialogue that users have with an interactive system that makes
use of visual elements and strategies exploiting visual clues and perception. In traditional VQSs,
visual interaction strategies are used to accomplish the two activities that make up data retrieval,
i.e., understanding the reality of interest and formulating the query. In more recent systems, visual
interaction also refers to the user's direct manipulation of the data display provided by the system.
Note that some VQSs allow more than one strategy for each activity.
Understanding the reality of interest
may be a complex task when the database schema is
made of hundreds or thousands of concepts and/or the extension of the database is made of millions
or billions of instances. What is needed is a mechanism to filter the information that is considered
significant by the user. This may be achieved by means of a
top-down strategy
, where general aspects
