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Information Modeling: The EXPRESS Way$
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Douglas Schenck and Peter Wilson

Print publication date: 1994

Print ISBN-13: 9780195087147

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195087147.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 18 June 2021

Sample Models

Sample Models

Chapter:
Chapter 20 Sample Models
Source:
Information Modeling: The EXPRESS Way
Author(s):

Douglas Schenck

Peter Wilson

Publisher:
Oxford University Press
DOI:10.1093/oso/9780195087147.003.0028

This Chapter contains a sampler of EXPRESS models, each of which has been used as the basis for the earlier EXPRESS-G model illustrations. No claim is made that the models are either realistic or good — the models have been constructed to show certain aspects of EXPRESS-G rather than to illustrate information modeling in general. Here is a summary of what the model in Example 20.1 says: a person must be either a male or a female. Every person has some defining characteristics, such as first and last names, date of birth, type of hair, and may also have zero or more children (which are, of course, also people). A male may be married to a female, and vice-versa. The partners in a marriage must be unique — this model is only appropriate for monogamous societies. There is one particular piece of information about females that does not apply to males; a female may have a maiden name. The Age of a person is a derived attribute that is calculated through the function years, which determines the number of years between the date input as a parameter and the current date. A Person has an inverse attribute which relates people who are children to their parents.

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