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{{Short description|Programming technique}}
{{Distinguish|
[[File:ORM-diagram-tkz-orm.png|406px|thumb|Example of an ORM2 diagram]]
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Object–role models are based on elementary facts, and expressed in [[diagram]]s that can be verbalised into natural language. A fact is a [[proposition]] such as "John Smith was hired on 5 January 1995" or "Mary Jones was hired on 3 March 2010".
With ORM, [[proposition]]s such as these, are abstracted into "fact types" for example "Person was hired on Date" and the individual propositions are regarded as sample data. The difference between a "fact" and an "elementary fact" is that an elementary fact cannot be simplified without loss of meaning. This "fact-based" approach facilitates modeling, transforming, and querying information from any ___domain.<ref name="orm.net">{{Cite web | url=http://www.orm.net/pdf/ORM2_TechReport1.pdf
=== Attribute-free ===
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[[Fact-based modeling]] includes procedures for mapping facts to attribute-based structures, such as those of ER or UML.<ref name="orm.net"/>
Fact-based textual representations are based on formal subsets of native languages. ORM proponents argue that ORM models are easier to understand by people without a technical education. For example, proponents argue that object–role models are easier to understand than declarative languages such as [[Object Constraint Language]] (OCL) and other graphical languages such as [[Unified Modeling Language|UML]] class models.<ref name="orm.net"/> Fact-based graphical notations are more expressive than those of ER and [[Unified Modeling Language|UML]]. An object–role model can be automatically mapped to relational and deductive databases (such as [[datalog]]).<ref>{{Cite web|url=http://www.ormfoundation.org/files/folders/orm_2010/entry2360.aspx|archive-url=https://web.archive.org/web/20110413060716/http://www.ormfoundation.org/files/folders/orm_2010/entry2360.aspx|url-status=usurped|archive-date=April 13, 2011|title=P:11 Mapping ORM To Datalog - an Overview - The ORM Foundation|website=www.ormfoundation.org|access-date=May 31, 2020}}</ref>
=== ORM 2 graphical notation ===
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* [[Ontology engineering]]
* [[Relational algebra]]
* [[Three
== References ==
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== External links ==
{{Commons category|Object role modeling}}
{{DEFAULTSORT:Object Role Modeling}}
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