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# Default Positioning of Entities in an Entity/Relationship Diagram

IP.com Disclosure Number: IPCOM000117986D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 38K

IBM

## Related People

Wilmsmann, G: AUTHOR

## Abstract

Disclosed is a program that creates a graphical layout for an Entity/Relationship (E/R) diagram by first assigning the entities to levels and second, determining the order of the entities inside a level. The levels appear in the diagram from the top to the bottom, starting with the first level at the top of the diagram. Furthermore, the assumption is that the entities to be placed in the E/R diagram are related to each other either through a direct relationship or through a relationship path via one or more other entities.

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Default Positioning of Entities in an Entity/Relationship Diagram

Disclosed is a program that creates a graphical layout for an
Entity/Relationship (E/R) diagram by first assigning the entities to
levels and second, determining the order of the entities inside a
level.  The levels appear in the diagram from the top to the bottom,
starting with the first level at the top of the diagram.
Furthermore, the assumption is that the entities to be placed in the
E/R diagram are  related to each other either through a direct
relationship or through a  relationship path via one or more other
entities.

The entity having the highest number of relationships to other
entities is assigned to the first diagram level.  Beginning with the
second diagram level, the n-th diagram level is made up of all
entities that are related to entities of the (n-1)-th level and that
are not yet  assigned to a diagram level.  This process ends when all
entities are assigned to a diagram level.

Now, beginning with the second level of the diagram, the order
of the entities of the n-th level of the diagram is determined.  The
entities of the n-th level are in an optimal order, if the number of
intersections of relationships between entities of the n-th level and
the number of intersections of relationships between entities of the
n-th level and the (n-1)-th level has a minimum value.  If this
criteria is fulfilled by several orders, the corresponding optimal
order of the ...