How Owl Imports Work - Revision history

Lee W. Lacy: fixed typo xm:base to xml:base LWL

2011-07-25T18:44:06Z

fixed typo xm:base to xml:base LWL

2009-02-24T18:07:04Z

‎OWL 1.0 Imports

2009-01-10T13:53:48Z

‎OWL Imports

2008-10-28T13:31:53Z

‎OWL Imports

2008-10-28T13:31:04Z

2008-04-29T15:57:38Z

‎Why Not Import By Location?

2008-04-29T15:52:27Z

‎Why Not Import By Location?

2008-04-29T15:46:09Z

‎Why Not Import By Location?

2008-04-29T15:39:44Z

‎Ontology Found Has The Wrong Name

2008-04-29T15:39:13Z

‎Ontology Found Has The Wrong Name

@@ Line 37: / Line 37: @@
 * the pizza ontology contains exactly one owl:Ontology declaration,
 * this declaration is named by rdf:about="",
-* the xm:base is declared and
+* the xml:base is declared and
 * the xml:base is a working URL that points to the pizza ontology.
 This situation is the simplest case and in this case things tend to work very smoothly.

@@ Line 1: / Line 1: @@
 = OWL 1.0 Imports =
-Before starting, I should point out that [http://www.w3.org/TR/owl2-syntax/#Imports the way imports work in OWL 2.0] is different than the way that imports work in OWL 1.0.  The short story is that the OWL 2.0 group has chosen import by location.  The OWL 2.0 scheme has not been fully implemented by either Protege 3 nor Protege 4, though both editors will load such import statements.  For more about our current understanding of OWL 2.0 imports see our new page [[How_Owl_2.0_Imports_Work|How imports work in OWL 2.0]].  This new scheme will be fully supported by future versions of the OWL API and Protege 4.
+Before starting, I should point out that the way [[How_Owl_2.0_Imports_Work|imports work in OWL 2.0]] is different than the way that imports work in OWL 1.0.  The short story is that the OWL 2.0 group has chosen import by location.  The OWL 2.0 scheme has not been fully implemented by either Protege 3 nor Protege 4, though both editors will load such import statements. This new scheme will be fully supported by future versions of the OWL API and Protege 4.
 First it must be understood that the semantics of imports in OWL is a subject of some controversy.  In the OWL 1.1 specification there is

@@ Line 1: / Line 1: @@
-= OWL Imports =
+= OWL 1.0 Imports =
-'''It appears that this discussion now only applies to OWL 1.0.  The OWL 2.0 working group has chosen import by location ([http://www.w3.org/TR/owl2-syntax/#Imports W3 OWL 3 Imports Definition]).'''
+Before starting, I should point out that [http://www.w3.org/TR/owl2-syntax/#Imports the way imports work in OWL 2.0] is different than the way that imports work in OWL 1.0.  The short story is that the OWL 2.0 group has chosen import by location.  The OWL 2.0 scheme has not been fully implemented by either Protege 3 nor Protege 4, though both editors will load such import statements.  For more about our current understanding of OWL 2.0 imports see our new page [[How_Owl_2.0_Imports_Work|How imports work in OWL 2.0]].  This new scheme will be fully supported by future versions of the OWL API and Protege 4.
 First it must be understood that the semantics of imports in OWL is a subject of some controversy.  In the OWL 1.1 specification there is

@@ Line 1: / Line 1: @@
 = OWL Imports =
-''It appears that this discussion now only applies to OWL 1.0.  The OWL 2.0 working group has chosen import by location ([http://www.w3.org/TR/owl2-syntax/#Imports W3 OWL 3 Imports Definition]).''
+'''It appears that this discussion now only applies to OWL 1.0.  The OWL 2.0 working group has chosen import by location ([http://www.w3.org/TR/owl2-syntax/#Imports W3 OWL 3 Imports Definition]).'''
 First it must be understood that the semantics of imports in OWL is a subject of some controversy.  In the OWL 1.1 specification there is

← Older revision		Revision as of 13:31, October 28, 2008
Line 1:		Line 1:
	= OWL Imports =		= OWL Imports =
		+
		+	''It appears that this discussion now only applies to OWL 1.0. The OWL 2.0 working group has chosen import by location ([http://www.w3.org/TR/owl2-syntax/#Imports W3 OWL 3 Imports Definition]).''

	First it must be understood that the semantics of imports in OWL is a subject of some controversy. In the OWL 1.1 specification there is		First it must be understood that the semantics of imports in OWL is a subject of some controversy. In the OWL 1.1 specification there is

@@ Line 120: / Line 120: @@
 * The internet is trusted, available and reliable, ontologies are never relocated, people choose to give their ontologies names that do not correspond to their physical location and all the ontologies of interest are on the internet.
-With import by location, the import will always be found.  With import by name, a person reading an ontology off the web may not be able to determine where to find the imported ontology.
+With import by location, the import will always be found.  With import by name, a person reading an ontology off the web may not be able to determine where to find the imported ontology.  While there are several conditions that need to be met for import by location to work, it must be noted that this is not an uncommon situation.
 Note that usually an ontology has a name that does not correspond to its physical location only when the ontology has been relocated.  When an ontology is relocated, the import by location scheme would require all ontologies making the import be modified.  Once the new location is updated in all importing ontologes we would be back in this use case where import by location works.

@@ Line 118: / Line 118: @@
 The one case where import by location shines and import by name does very badly is the following:
-* The internet is trusted, available and reliable, ontologies are never relocated and all the ontologies of interest are on the internet.
+* The internet is trusted, available and reliable, ontologies are never relocated, people choose to give their ontologies names that do not correspond to their physical location and all the ontologies of interest are on the internet.
 With import by location, the import will always be found.  With import by name, a person reading an ontology off the web may not be able to determine where to find the imported ontology.
 I will lump the other use cases together but they may have important differences.

@@ Line 101: / Line 101: @@
 In Protege 4 the visual cue is the little green triangle to the right in the diagram below:
 [[Image:HowOwlmportsWorkProtege4Broken.png]]
 A nice feature of Protege 4 is that clicking on the green triangle will bring up a dialog that asks if you want to fix the import:
 [[Image:HowOwlmportsWorkProtege4Fix.png]]
 The advantage of fixing the import is that it will be easier to edit the ontology offline, tools will work better  and the ontology will be suitable for use with an application.  The disadvantage is that users and tools will either have to know or be told the correct location for the ontology.