Shanghai University, "The Semantic Web and knowledge map" in Review of (a)
Foreword
This lesson. . I do not like. But you can not hang ah! Normally, then find it hard to listen in, because there is no pilot class, this is a bit uncomfortable directly, the teacher felt he wanted to express a lot of things, but some things do not clear expression, have stumbled hear each lesson, after all It is a cutting-edge stuff, if not front-line combat teacher, estimated that many concepts are difficult to clear it.
Above all nonsense, if I really have one day to spend it? (Hell).
The following review focuses on the possible review of the test sites, where all individuals may feel the topic and so on.
Before summed up rdf / rdfs, turtle and owl grammar, so here earlier review would be relatively simple to write
Before summarizing the link:
Semantic Web and knowledge map entry (a)
Semantic Web and knowledge map entry (b)
Semantic Web Overview
Ontology: ontology is a formal, clear and detailed description of the concept for a shared system. Provide a shared vocabulary .... Ontology is a classification describing the objective world. Remember this category.
In fact, we still do not know that he expressed this definition What do you mean, I understand that the body is a way of describing this thing, to describe the relationship between things, this relationship can be abstract relationships, such as between classes and instances the relationship can also be property relations.
Remember this: implement technology to be the most important is to have the right knowledge representation language.
Remember this: the core of the body is usually classification system.
RDF
RDF is a resource description language. , Predicates and objects described by the subject.
The relationship between an object is RDF graph rather than a tree.
Elements of RDF: URI, text, empty node.
URI is the address of the resource, the text refers to the string type of resource, empty node that is also well understood.
Turtle
URI must be placed <>, and each sentence to use. End.
@Prefix prefix can be expressed, for example, to define good
@prefix book: <http://a.com>.
So next time use can be expressed directly book <http://a.com> URI of this.
turtle is relatively simple grammar, syntax rdf are no longer summed up, on the back of the owl syntax also mentioned.
XML
Xml used to describe the RDF syntax, turtle just easier to write, but when used with xml, or more.
As an example
<rdf:Description rdf:about="http://a.com">
<ex:publishedBy>
<rdf:Description rdf:about="http://b.com">
</rdf:Description>
</ex:publishedBy>
</rdf:Description>This example is the syntax rdf next incomplete xml, description indicates that this is a node, and rdf: is the uri, pointing to what is contained within the next node of about description and directed edges.
The resource written brief: the above example there is a rdf use.
<rdf:Description rdf:about="http://a.com">
<ex:publishedBy rdf:resource="http://b.com">
</ex:publishedBy>
</rdf:Description>The effect is the same.
The above two examples are incomplete, because there is no space plus the name, in fact, there is the need for xml namespace.
<rdf:RDF xmlns:rdf="http:xx.com" xmlns:ex="http://xxx.com">
<rdf:Description rdf:about="http://a.com">
<ex:publishedBy rdf:resource="http://b.com">
</ex:publishedBy>
</rdf:Description>
</rdf:RDF>Here a circle surrounding the outside rdf: RDF, and the xml namespace are described rdf and ex, and specified uri.
There is some place to distinguish the differences in syntax, rdf: resource node is a simplified version of rdf description representatives sometimes use rdf: id, rdf here: id = "aa" is actually equivalent to rdf: about = "http: //xx.com#aa" such a uri.
I think there is a PPT on the more important examples:
@prefix ex:<http://exmaple.org> .
ex:GreenTea ex:hasIngredient "1 kg water",
"2 kg tea".This structural expression is not very good, it is clear that we believe should and specific water, tea apart right.
So did such modifications
@prefix ex:<http://example.org> .
ex:GreenTea ex:Ingredient "water"; ex:amount:1;
ex:Ingredient "tea"; ex:amount:2.After such a change is also inappropriate, because the number and water, tea separated, examples of the above expression became green tea materials are water, tea is the number 1, in fact, be ambiguous. To address this ambiguous relationship that we leads to empty nodes.
After a quick introduction of expression blank nodes it?
@prefix ex:<http://example.org> .
ex:GreenTea ex:Ingredient (
[
ex:name "water";
ex:amount:1
],
[
ex:name "tea";
ex:amount:2
]
).
Also with a list syntax. Ok.
Drawing Blank node does not need to uri, uri, like general shape and use of the block is oval, text.
In xml syntax with rdf: specify parseType = "Resource" an empty node
Left container syntax. I think not test it (possible examination turtle, but very simple).
RDFS
Basic grammar
RDFS is to add RDF Schema, and more specifically, said object-oriented features, like C and C ++ upgrade, RDFS is such an identity.
rdf: type and the relationship between a particular instance of the class, the former belongs to the latter .eg book: uri rdf: type ex: TextBook.
rdfs: subClassOf, describes a class to another class contains relations, eg ex: TextBook rdfs: subClassOf ex: Book.
All classes subClassO a base class, i.e. rdf: Class, then there are many predefined classes, such as rdfs: Resource and rdfs: Property like.
Property Restrictions
You can constrain a domain and range properties.
ex:hasAge rdfs:range xsd:nonNegativeInteger.Here hasAge negative attributes defined by a non-range, xsd: nonNegativeInteger is rdfs predefined data type constraint.
Semantic
Logical semantics
Began to nonsense.
Semantics of logic programs include: model theory and proof theory.
Semantics are the result produced by the interaction between the information obtained, such as another node contains a node, comprising interaction between two nodes is, the result of this interaction is generated by a containment relationship, which is semantics. And we could not get a word from the surface of his semantics, because the surface sentence of this thing is no way to calculate, it is not expressed in mathematical form, so I can not express the semantics (the semantics defined by mathematical) we define .
On the semantic model
It is the definition of a model by a mathematical model to express the results of one meaning. For example, I defined a model of f, f (1) = 1, f (2) = 2, where I can use this function to express the value of the results of a semantic, such as the number and so on, anyway, is the mathematical definition of good An expression. I was so simple to understand.
Semantic interpretation model to provide a kind of mapping relationship where the mapping relationship is defined by people, once you've defined the mapping relationship, then this interpretation on the set. ppt on a large pile of things that do not know why.
OWL
OWL location is rdfs above, is to say that after layer upgrade.
I think we can merge between classes where progress is described Yeah, it can be mutually exclusive, or between instances, the relationship between property, this is the number of categories combined, is a big step forward.
Namespace what not to say, the definition of the class became owl: Class, which is the base class owl: Thing.
And individual instances of the class:
类定义
<owl:Class rdf:ID="A">
<owl:Class rdf:ID="B">
<rdfs:subClassOf rdf:resource="#A">
</rdfs:subClassOf>
</owl:Class>
</owl:Class>
实例定义
<B rdf:ID="b">
</B>
You can see, you can directly take the class name to instantiate an object it!
In fact, I wrote a blog OWL, do not continue to write before, and before write or very detailed sense, so before looking directly at the blog review on OK.