我们都知道，RDF只表示二元关系，但在实际应用中，多元关系非常常见，如：小红借给小明语文书，是个三元关系： borrow(小红，语文书，小明); 再如，小明的身高是170cm.也是个三元关系 length(小明，170, cm). 推广来说，n元关系如何在RDF和OWL中表示呢？

我们假设三元组为(a,b,c). a,b.c 都是资源或Literal

1． 方法一
如果三元组中a是老大，即有个资源的地位是支配性的，如:小明的身高是170cm.
表示方法为 把老大提出来，再把三元关系分解为3个二元关系：
  R1(a, a’) ， R2（a’,b）,  R3（a’,c）  // R1(a, a’) 用RDF三元组表示为 （a , R1 , a’）
例如：小明的例子可以表示为
length(小明，length_obj_1);  //小明是老大, length_obj_1 是一个身高对象
value(length_obj_1，170);     //值
unit(length_obj_1，cm);      //单位
2． 方法二
如果三元组中没有明显的老大，如: 小红借给小明语文书.
表示方法为提出一个对象，每个元素都和这个对象有关系：
R1(g, a) ， R2（g,b）,  R3（g, c）
例如：小红借书的例子可以表示为
rdf:type (borrow_obj_1,  BorrowRelation); // BorrowRelation 是一个表示借书关系的类
borrow_owner((borrow_obj_1,小红)；
borrow_agent((borrow_obj_1,小明)； //借书的人
borrow_book((borrow_obj_1, 语文书)；

3． 结论
1) n-元关系有2exp(n-2) 种表示方法： 二元关系一种表示法，三元关系有如上二种表示法，由数学归纳法得证。
2) 如果用RDF对复杂系统建模，有必要引入一个中间的抽象层，用以表示N元关系，还有named graph, context 等。如引入rdfe:relation(a,b,c,d,….)表示n元关系
3) n-关系的表示对RDF数据的查询和存储优化很有价值，因为n-关系往往对应了数据库中的表。

注：大部分摘译自：
http://www.w3.org/2001/sw/BestPractices/OEP/n-aryRelations-20040623/

更为详细的信息也参考它。

熟悉DAML+OIL的人可能还记得有属性：minCardinalityQ，maxCardinalityQ，它们是
Qualified cardinality restrictions（QCR，我翻译为受限基数约束,不知妥当否），但OWL规范认为它们过于复杂去掉了。但他们在实际建模中很有用，特别是对part-whole关系,而part-whole关系在空间，解剖学，产品本体中很常见。例如，我们要表示：一个手有5个手指且其中有一个是拇指，用描述逻辑可以表示为：＝5 hasFinger ; ＝1 hasFinger.Thumb. 再举个例子，如学校可以申请答辩的博士至少要发表一篇SCI收录的文章， >=1 hasPaper. SCIPaper  (>= 表示至少，即大于等于)。 受限基数约束在OWL中如何表示呢？

方法一：用owl:someValuesFrom

owl:someValuesFrom 实际上是受限基数约束的一种特殊形式，它表示： 这个属性至少有一个属于某类型的值. 上面SCI文章的例子可以表示为:

  Class(可申请答辩的博士,
    subClassOf(Restriction(hasPaper, someValuesFrom(SCIPaper)))

方法二: 用subPropertyOf

第一种方法只适用与基数至少1的情况，更一般的情况，可以引一个新的子属性. 这个属性的值域就是那个类型，例如，SCI文章那个例子可以这样表示：

Property(hasPaper)       //属性hasPaper 的值域是Paper
Property(hasSCIPaper   
  subPropertyOf(hasPaper))  //属性hasSCIPaper 的值域是SCIPaper,它是Paper的子类
Class(可申请答辩的博士
   subClassOf(Restriction(hasSCIPaper minCardinality(1))))

对5个手指的例子可以表示为：
Property(hasFinger)
Property(hasThumb    
  subPropertyOf(hasFinger))
Class(NormalHand
  subClassOf(Restriction(hasFinger cardinality(5)))
  subClassOf(Restriction(hasThumbe cardinality(1))))

方法二引入了一个新的属性，如果part-whole关系很复杂，如零部件很多，像飞机，轮船，则这种表示方法会显得非常邋遢。最好的方法是直接支持QCR,值得一提的是描述逻辑的推理机RACER支持QCR. 所以，有的系统可能会对扩展OWL语言，从而支持QCR.

注：大部分摘译自：Guus Schreiber,http://www.cs.vu.nl/~guus/public/qcr.html , first draft , 25 May 2004

在OWL DL中提供了枚举类(oneOf)的功能，遗憾的是，就是因为这个oneOf,目前尚没有有效的算法完全支持OWL DL 本体的蕴涵推理，常用的描述逻辑的推理机Fact, Racer都不支持枚举类。因此，在目前的实际应用中，我们应避免使用它。但碰到直观上需要枚举类的情况，例如，描述一个人的健康状况：健康(good health)，一般(medium health),不健康(poor health), 怎么办呢？用枚举类的话，很直观：即健康状态这个类是由三个实例枚举组成的类。如下表示：

Class (Health_value equivalentClass
                   oneOf (medium_health good_health poor_health))

现在，我们提出一个oneOf 的替代方法：即把实例全升级为类。
我们可以把 健康，一般,不健康 都作为一个健康状态的子类，他们是两两分离的(disjoint),且健康状态类是这三个类的并集。如下表示：

Class(Health_Value  equivalentClass
             unionOf (Poor_health_value  Medium_health_value  Good_health_value))

Class(Good_health_value paritial Health_Value) // Good_health_value 是Health_Value 的子类
Class(Medium _health_value paritial Health_Value)
Class(Poor _health_value paritial Health_Value)

disjointClasses(Good_health_value ,Poor_health_value , Medium_health_value))

这样，如果要表示一个健康的人，可以说健康状况属性至少有个值是属于”健康”这个类的。

// has_health_status: 健康状况，函数型对象属性，值域：Health_Value, 定义域：Person
Class(Healthy_person equivalentClass
           intersectionOf(Person  and
                     restriction(has_health_status  someValuesFrom  Good_health_value)))

要表示某个人是健康的，只要它的has_health_status 值是类Good_health_value的一个实例 即可。

Individual (John  type  Person
                        has_health_status   John_health）

Individual(John_health  type  Good_health_value )
或者直接说

Individual(John type Person
                     type  restriction(has_health_status  someValuesFrom  Good_health_value))

总结：
  通过把实例升级为类，可以避免使用枚举类，但是很不直观。但这样做还有一个好处：我们可以进一步细分健康状态，如健康可以再分为非常健康，非常非常健康。但用枚举类是不可以的，因为实例只有相同和不同，不可能有重叠。

备注：
    Racer虽然不支持对实例的枚举，但支持对数据值的枚举。

参考：
   Alan Rector，Representing Specified Values in OWL: "value partitions" and "value sets" W3C Working Draft 12 June 2004。

http://www.w3.org/2001/sw/BestPractices/OEP/Lists-of-values-20040625/

Representing Classes As Property Values on the Semantic Web
2004-07-21: The Semantic Web Best Practices and Deployment (SWBPD) Working Group has released the First Public Working Draft of [URL=http://www.w3.org/TR/2004/WD-swbp-classes-as-values-20040721/]Representing Classes As Property Values on the Semantic Web[/URL]. Comments are welcome. The draft examines approaches to using classes as property values in OWL DL. OWL DL supports users of the [URL=http://www.w3.org/2004/OWL/]OWL Web Ontology Language[/URL] who want computational completeness and decidability. Visit the [URL=http://www.w3.org/2001/sw/]Semantic Web home page[/URL]. ([URL=http://www.w3.org/News/2004#item109]News archive[/URL])

争取8。1号以前完成。 ；－）

看了些关于用OWL构建本体的讲义和教程，其中都会提到OWL的逻辑基础描述逻辑中的推理是基于开放世界假设(Open World Assumption)的，从而在构建本体时要特别注意这点。因此，我小小的总结一下，但并没有深入去研究开放世界语义，故不能保证正确性，欢迎大家讨论。

当我们对现实世界的问题做形式化描述时，不可避免地掌握的信息是不完全的，例如，我们不知道Peter是否是个Student，但这个信息的确又是很有用的。一种常用的做法是采用封闭世界假设(Closed World Assumption, CWA), 即如果我们在知识库中推不出来P或P的否定，就把P的否定加入知识库。有两种情况, CWA很有用. 一是可以当假设知识库中的知识是完全的时候. 例如, 在数据库中, 如果学生表中没有Peter, 则认为Peter不是学生. 二是当知道知识库的知识是不完全的, 如不足于回答一些问题, 但我们必须在不完全知识的情况下做出决定, 这时候CWA就有用了. 其实, 我们人思考问题也常常是这样的, 例如, [@todo]

对不完全知识的处理的另外一种方法就是采用开放世界假设(Open World Assumption, OWA), 它和CWA相反, 对推不出来的命题就很诚实地当作不知道这个命题的正确与否, 这样的后果就是知识库中能推导出来的结论大大减少.

但在语义Web环境下, 因为Web的开放性, 相关的知识很可能分布在Web上不同的场所, 因此在语义Web上推理, 用CWA是很不恰当的. 例如, 如果在一个知识库中只说了hasFriend(Peter, Tom), 如果采用CWA, 就会得到结论: Peter只有一个朋友. 这当然是不合理的, 因为很可能在别的地方说了Peter还有其他的朋友. 所以, 如果要在语义Web中聚集不同来源的知识, 应该采用OWA. (有一种中庸之道: 局部封闭世界(Local Closed World), 这里不多说). 描述逻辑中的推理刚好是采用OWA的, 所以它的确适合作为语义Web的逻辑基础.

OWA对本体构造有很大的影响, 因为OWA 认为, 没有显式说明的信息就是未知, 因此,我们在构建本体的时候, 要记住一个原则:  “把你知道的全说出来”!

现在，我们看看怎样在OWL本体中说出那些你实际上知道, 但容易忘了说的东西.

1） 唯一名假设(Unique Name Assumption, UNA)： owl:AllDifferent
逻辑中一般采用唯一名假设，即名字不同的两个实例是不同的，而OWL由于Web的开放性，很有可能不同的人对同一个实例给出的URIref不同，因此不能采用唯一名假设。这也是要有owl:AllDifferent的原因。因为在OWL中，我们要显式地说明哪些URIref代表的资源是不同的，如果用owl:differentFrom，要表示很多个URIref两两不同，非常麻烦，因此，就有了owl:AllDifferent。

注意: RACER 支持唯一名假设. 这点使得它不是很适合做SW上的推理. 当然, 新版本也许会改进.
2） 分离和覆盖： owl:disjointWith

在定义类的时候, 可能定义B和C都是A的子类, 这时候可能会忘了说明B和C是Disjoint的, 这个信息对公理中用了否定比较有用, 因为这可以推出, B的实例肯定不属于C, 另外, 还一个容易忘的是覆盖公理(covering axiom).，即说明B和C的合取 覆盖了A(即A是B和C的并的子集), 因为这可以进一步推出: 如果x是A的实例, 且不是B的实例, 则x是C的实例.
最牛的覆盖定理当然是说B是C的否定, 即B和C的合取覆盖了整个论域, 这样, 一个实例x不属于B则属于C.

3） 实例识别：owl:maxCardinality , owl:allValuesFrom

OWA还有一个很坏的影响是对有些类, 你永远没法判定这个实例是否属于这个类. 例如, 我们定义类D是具有最多2个孩子的人, 现在有个实例y, 知识库中说了y有两个孩子, 但我们能推出y是属于类D的实例吗? 不能! 因为采用OWA, 推理引擎会认为也许其他地方还会说y有第3个孩子, 所以推不出y至多只有2个孩子. 类似的是OWL的属性限制allValuesFrom, 因为你也无法保证 这个”all”能成立.

结论是: 如果你的应用中需要判定实例属于某个类, 谨慎使用owl:maxCardinality和owl:allValuesFrom.

4） 封闭公理
OWA会导致一些麻烦, 原因是我们没有把”我们知道的全说出来”. 解决方法就是采用封闭公理(closure axioms), 把路子堵死. 下面有两种常用的封闭公理.

     a).用allValuesFrom 封闭 someValuesFrom

        先举个例子, 假如类A定义为所有孩子都是学生的人, 即 A= restriction(allValuesFrom hasChild Student); 现在已知类B定义为有孩子是高中生, 有孩子是大学生, 即:

Class(B  partial
        Restriction(someValuesFrom hasChild HighSchool ) )
Class(B  partial
        Restriction(someValuesFrom hasChild  College ) )

这时,我们能推出B是A的子类吗?

按照OWA, 答案是不能, 因为你没说 B的孩子都是学生, 你只说他的孩子有高中生,有大学生. 所以, 为了让B是A的子类, 你要把事情说死, 即加一个封闭公理:

Class(B  partial
        Restriction(allValuesFrom hasChild  unionOf(College HighSchool) ) )

即说明  B 的孩子都是高中生或大学生, 再加上高中生和大学生都是学生的子类, 我们才可以推出 B 是 A 的子类.

总结:
“A closure axiom on a property consists of a universal restriction that acts along the property to say that it can only be filled by the specified fillers. The restriction has a filler that is the union of the fillers that occur in the existential restrictions for the property”.

      b)用cardinality =n  封闭  allValuesFrom

          上面提到如果用allValuesFrom定义一个类, 则永远无法判定一个实例是否属于这个类, 封闭的方法就是加上一个基数限制. 如, 定义类A是有3个孩子且所有孩子都是博士的人,这样如果实例a有三个孩子b,c,d 且b,c,d 都不是相同的人(AllDifferent), 且b,c,d都是博士, 这样就可以推出a是属于类A了.

参考
[1] Ian Horrocks的关于构建本体的课程讲义
[2] DL handbook chapter 2: P26   2.2.4.4 Closed- vs. open-world semantics
[3] protégé owl tutorial  http://www.co-ode.org/resources/tutorials/ProtegeOWLTutorial.pdf

以下是引用orangebench在2004-8-3 13:09:01的发言： 开放世界语义对本体构建的影响 看了些关于用OWL构建本体的讲义和教程，其中都会提到OWL的逻辑基础描述逻辑中的推理是基于开放世界假设(Open World Assumption)的，从而在构建本体时要特别注意这点。因此，我小小的总结一下，但并没有深入去研究开放世界语义，故不能保证正确性，欢迎大家讨论。 [snip] 参考 [1] Ian Horrocks的关于构建本体的课程讲义 [2] DL handbook chapter 2: P26   2.2.4.4 Closed- vs. open-world semantics [3] protégé owl tutorial  http://www.co-ode.org/resources/tutorials/ProtegeOWLTutorial.pdf

2004-08-03: The Semantic Web Best Practices and Deployment (SWBPD) Working Group has released the First Public Working Draft of [URL=http://www.w3.org/TR/2004/WD-swbp-specified-values-20040803/]Representing Specified Values in OWL: "value partitions" and "value sets."[/URL] Comments are welcome. The draft presents methods for representing modified values and collections of values in the [URL=http://www.w3.org/2004/OWL/]OWL Web Ontology Language[/URL]. Visit the [URL=http://www.w3.org/2001/sw/]Semantic Web home page[/URL]. ([URL=http://www.w3.org/News/2004#item126]News archive[/URL])

OWL DL 本体构建指南
                  摘自  OWL Pizzas: Common errors & common patterns from practical experience of teaching OWL-DL

1. Always paraphrase a description or definition before encoding it in OWL,
and record the paraphrase in the comment area of the interface.
在用本体表示以前，用自然语言描述清楚你想表达的意思
2. Make all primitives disjoint - which requires that primitives form trees
使得没有完全定义的类互为不交
3. Use somevaluesFrom as the default qualifier in restrictions
allvaluesFrom 并不蕴涵somevaluesFrom, 缺省情况下使用somevaluesFrom
如果用allvaluesFrom ,或maxCarndinality定义类, 由于DL采用开放世界假设，使得无法判定
一个实例属于这个类。
4. Be careful to make defined classes defined – the default is primitive. The
classifier will place nothing under a primitive class (except in the presence
of axioms /domain/range constraints)
谨慎给出类的完全定义。
5. Remember the open world assumption. Insert closure restrictions if that is
what you mean.
注意描述逻辑中的开放世界假设，这与数据库不同，如果需要的化加入封闭世界公理。
6. Be careful with domain and range constraints. Check them carefully if classification
does not work as expected.
谨慎给出类的定义域和值域约束，他们是全局约束，可能会导致不期望的结果
7. Be careful about the use of “and” and “or”(intersectionOf, unionOf )
注意逻辑意义上的“and”和“or”和自然语言中的区别
8. To spot trivially satisfiable restrictions early, always have an existential
(somevaluesFrom) restriction corresponding to every universal (allvaluesFrom)
restriction, either in the class or one of its superclasses (unless you specifi-
cally intend the class to be trivially satisfiable).
如果想表达某个类的属性值必须都是属于一个类的，别忘了加上somevaluesFrom限制.
参考：http://bbs.xml.org.cn/dispbbs.asp?boardID=2&ID=8036
9. Run the classifier frequently; spot errors early
频繁运行分类器，早点发现错误。

[From Uschold, Michael F in public-swbp-wg@w3.org]

Below is a good source for a quick summary of the Gruber ontology on physical quantities, units and dimensions.  Note that As encoded in Ontolingua, Gruber's 'ontology' is not a single ontology, but rather a collection of modules, each technically single ontologies.

Mike
===
Ontology Reuse and Application
Reference: Mike Uschold, Mike Healy, Keith Williamson, Peter Clark, Steven Woods.
Ontology Reuse and Application. In Proceedings of the International Conference on Formal Ontology and Information Systems - FOIS'98 (Frontiers in AI and Applications v46), pages 179-192, Ed: N. Guarino, Amsterdam:IOS Press, 1998.

Abstract: In this paper, we describe an investigation into the reuse and application of an existing ontology for the purpose of specifying and formally developing software for aircraft design. Our goals were to clearly identify the processes involved in the task, and assess the cost-effectiveness of reuse. Our conclusions are that (re)using an ontology is far from an automated process, and instead requires significant effort from the knowledge engineer. We describe and illustrate some intrinsic properties of the ontology translation problem and argue that fully automatic translators are unlikely to be forthcoming in the foreseeable future. Despite the effort involved, our subjective conclusions are that in this case knowledge reuse was cost-effective, and that it would have taken significantly longer to design the knowledge content of this ontology from scratch in our application. Our preliminary results are promising for achieving larger-scale knowledge reuse in the future.

PDF: http://www.cs.utexas.edu/users/pclark/papers/fois98.pdf
Compressed postscript: http://www.cs.utexas.edu/users/pclark/papers/fois98.ps.Z

peter.e.clark@boeing.com <http://www.cs.utexas.edu/users/pclark>  

http://oiled.man.ac.uk/building/

Building DAML+OIL Ontologies
This page provides pointers to material that help you go from ontology principles to practice using DAML+OIL. It is designed to provide some answers to the common question: I want to build an ontology of x using DAML+OIL. Where do I start? This site is not intended to give a comprehensive coverage of the specification of DAML+OIL, which is covered at the main DAML+OIL [URL=http://www.daml.org/]website[/URL].

General Information on building ontologies
Certain principles of ontological engineering are independent of the language used to implement them.

Tutorials
N. Noy and D. L. McGuinness. [URL=http://protege.stanford.edu/publications/ontology_development/ontology101-noy-mcguinness.html]Ontology Development 101: A Guide to Creating Your First Ontology[/URL]
A. Maedche and S. Staab. [URL=http://events.aifb.uni-karlsruhe.de/ontologytutorial/]Tutorials[/URL] on Ontologies from [URL=http://www.aifb.uni-karlsruhe.de/]AIFB[/URL].
Papers
M. Uschold and M. Gruninger. Ontologies: Principles, methods and applications. Knowledge Engineering Review, 11(2), 1996. Also available as AIAI-TR-191 from AIAI, The University of Edinburgh.
M. Uschold & R. Jasper. [URL=http://citeseer.nj.nec.com/257410.html]A Framework for Understanding and Classifying Ontology Applications[/URL]
M Fern&Aacute;ndez, A Gomez-Perez, N Juristo. [URL=http://delicias.dia.fi.upm.es/miembros/ASUN/SSS97.ps]METHONTOLOGY: From Ontological Art Towards Ontological Engineering Workshop on Ontological Engineering[/URL]. Spring Symposium Series. AAAI97 Stanford, USA.
D. L. McGuinness. [URL=http://www.ksl.stanford.edu/people/dlm/papers/ontologies-come-of-age-abstract.html]"Ontologies Come of Age".[/URL] In Dieter Fensel, Jim Hendler, Henry Lieberman, and Wolfgang Wahlster, editors. Spinning the Semantic Web: Bringing the World Wide Web to Its Full Potential. MIT Press, 2002.
D. L. McGuinness. [URL=http://www.ksl.stanford.edu/people/dlm/papers/dls-emerge-abstract.html]"Description Logics Emerge from Ivory Towers".[/URL] Stanford Knowledge Systems Laboratory Technical Report KSL-01-08 2001. In the Proceedings of the International Workshop on Description Logics. Stanford, CA, August 2001.
Presentations
D. L. McGuinness. [URL=http://www.daml.org/2001/06/swday-ontologies/]Ontologies: What they are; Why you should care;What you should know.[/URL] Invited talk for Defense briefing series entitled The Semantic Web and the Military. Presented June 5, 2001 and February 16, 2001.
Information on building ontologies for the web
Several courses and tutorials cover the principles of ontologies and their construction from the contrasting viewpoints of the [URL=http://www.semanticweb.org/]Semantic Web[/URL] and the [URL=http://www.semanticgrid.org/]Semantic Grid [/URL]

Semantic Web Courses
[URL=http://www.cs.vu.nl/%7Emarta/wbkr.html]Web Based Knowledge Representation Course[/URL], Vrije Universiteit Amsterdam. In particular the 2nd lecture is on ontologies in general, with [URL=http://www.cs.vu.nl/%7Emarta/slides/wbkr_c2.pdf]slides[/URL] by [URL=http://www.cs.vu.nl/%7Emarta/]Marta Sabou[/URL].
[URL=http://www.cse.lehigh.edu/%7Eheflin/courses/sw-fall01/]Course on the Semantic Web[/URL], organised by Prof Jeff Heflin at Lehigh University.
Semantic Web Presentations
[URL=http://reliant.teknowledge.com/AAAI-2002/Fikes-keynote.ppt]Ontologies and the Semantic Web[/URL] by Prof. Richard Fikes, Knowledge Systems Laboratory, Stanford University.
Semantic Web Portals
The OntoWeb Network provides a [URL=http://qmir.dcs.qmul.ac.uk/ontoweb/]portal[/URL] for the benefit of the semantic web community.
Semantic Grid Presentations
Carole Goble's [URL=http://www.cs.man.ac.uk/%7Ecarole/old/GGF/FinalTutorial/]Ontology Tutorial[/URL] based on that presented at Global Grid Forum 5, Edinburgh, 2002.
[URL=http://www.cs.man.ac.uk/~carole/old/GGF%20Tutorial%20Stuff/]Background material[/URL] from Carole Goble.
Other Semantic grid based [URL=http://www.semanticgrid.org/presentations/]presentations[/URL]
Description logic based ontologies
Description logic ontologies differ in their approach to construction. Rather than manually create a hierarchy and then assign properties to concepts, the process is turned on its head. Each concept is assigned a logic definition which is then used to derive a classification. There is more than one way to classify a set of concepts. This approach allows different classifications to be produced for different purposes based on the same underlying terminological knowledge.

Description logic based ontologies can be useful because they provide:

Scalability. The reasoner can be used to maintain hierarchies and detect logical inconsistencies in concept descriptions.
Extendability. Description logics provide a formal semantic grammar with which complex concepts can be built from simpler building blocks. The initial authors of the ontology now only have to provide the building blocks, and constraints on how they can be composed. Specific concepts can be formed at the point of use.
Explicitness. Requiring formal concept definitions forces authors to be much more explicit and precise about their intended meaning for a concept. This can aid interpretation both by other humans and machines.
Detailed information on description logics can be found at the [URL=http://www.ida.liu.se/labs/iislab/people/patla/DL/index.html]Description Logics Home Page[/URL].

Information on the use of description logics to support the semantic web can be found on [URL=http://dl-web.man.ac.uk/]Jeff Z. Pan's pages[/URL]

[URL=http://www.cs.man.ac.uk/~seanb]Sean Bechhofer[/URL] and [URL=http://www.cs.man.ac.uk/~horrocks]Ian Horrocks[/URL] have produced a [URL=http://wonderweb.man.ac.uk/deliverables/D1.shtml]document[/URL] describing OWL as part of the [URL=http://wonderweb.man.ac.uk/]WonderWeb[/URL] project. This also contains a short tutorial introduction to the language.

Building DAML+OIL Ontologies to take advantage of description logic reasoning
Tutorials
Angus Roberts has written a [URL=http://oiled.man.ac.uk/tutorial]tutorial[/URL] on how to use OilEd to create simple DAML+OIL ontologies.
Alan Rector has written a [URL=http://www.cs.man.ac.uk/mig/ontology-tutorial/oiled-biomedical-ontology-tutorial.zip]tutorial[/URL] on creating biomedical ontologies in DAML+OIL using OilEd.
Ontologies
The DAML site maintains a [URL=http://www.daml.org/ontologies/]library[/URL] of DAML+OIL ontologies.
Within Manchester we are working on two domains
web service ontologies for bioinformatics[URL=http://mygrid.man.ac.uk/rsoftware.shtml](current prototype version available here)[/URL].
[URL=http://www.geneontology.org/]Gene Ontology[/URL] in DAML+OIL. The syntactic transformation from GO RDF to DAML+OIL is available [URL=http://gong.cs.man.ac.uk/]here[/URL].
Projects
[URL=http://gong.man.ac.uk/]GONG[/URL]
Gene Ontology Next Generation. A DAML+OIL based project to provide a more explicit conceptualisation of the Gene Ontology.
[URL=http://goat.man.ac.uk/]GOAT[/URL]
Gene Ontology Annotation Tool. A DAML+OIL based project to provide more flexible tools to annotate bioinformatics data.
[URL=http://clef.man.ac.uk/]CLEF[/URL]
Clinical eScience Framework. Investigating the use of DAML+OIL for medical applications.
[URL=http://cohse.semanticweb.org/]COHSE[/URL]
The Conceptual Open Hypermedia Service Project. The project uses a DAML+OIL based ontological reasoning service which is used to represent a sophisticated conceptual model of WWW document terms and their relationships.
[URL=http://www.mygrid.org.uk/]myGRID[/URL]
Bioinformatics grid project. Uses DAML+OIL ontologies to conceptually describe services and so facilitate their discovery.