Weronika Furmańska ikaf@student.agh.edu.pl

Porównać i omówić metody reprezentowania atrybutów w językach:

• RDF
• OWL
• RIF
• R2ML
• RuleML
• Semantic Web Rule Language http://www.w3.org/Submission/SWRL/

oraz metody reprezentowania reguł w:

• RIF
• R2ML
• RuleML
• ERDF

co to jest datalog…

business rules orchestration

tools: http://sweetrules.projects.semwebcentral.org/

people http://www.mit.edu/~bgrosof/

concepts: http://en.wikipedia.org/wiki/Description_Logics

• Jaki poziom szczegółowości projektu? Na próbę fragment o RDF - czy może być tak?
• Moje podejście - bardziej odpowiedź na pytania postawione w temacie, bez wnikania w szczegóły techniczne - słuszne?

Draft…

While talking about attribute-based languages we can recognize the following types of logic:

• AAL – Attributive Logic, i.e. attributive logic with atomic values of attributes only
• SAL – Set Attributive Logic, i.e. attributive logic with set values of attributes
• VAAL – Variable Atomic Attributive Logic, i.e.attributive logic with atomic values of attributes incorporating variables
• VSAL - Variable Set Attributive Logic, i.e.attributive logic with set values of attributes incorporating variables

Let there be the following, pairwise disjoint sets of symbols: O – a set of object name symbols A – a set of attribute names D – a set of attribute values names (the domains) V – a set of variable symbols (variables)

If the set of attributes is finite and given as

then
,
where Di is the domain of attribute Ai , i=1, 2, …,n.

Attributes in AAL and VAAL
An attribute Ai is a function (or partial function) of the form:

An attribute can be a partial function, since not all the attributes must be defined for all the objects.

Generalized attributes in SAL and VSAL A generalized attribute Ai is a function (or partial function) of the form

1. RDF identifies things using Web identifiers (URIs)
2. RDF is written in XML. The language is called RDF/XML.
3. The main elements of RDF are the root element, <RDF>, and the <Description> element, which identifies a resource.
4. <rdf:RDF> is the root element of an RDF document. It defines the XML document to be an RDF document. It also contains a reference to the RDF namespace. <rdf:RDF xmlns:rdf=„http://www.w3.org/1999/02/22-rdf-syntax-ns#”
5. The <rdf:Description> element identifies a resource with the rdf:about attribute. This element contains elements that describe the resource.

„RDF is based on the idea that the things being described have properties which have values, and that resources can be described by making statements that specify those properties and values. RDF uses a particular terminology for talking about the various parts of statements.” (W3C RDF Primer) Attributes are represented in RDF in a form of RDF Triples (subject, predicate, object) where subject denote the resource being described, predicate indicate the name of the attribute and object points to the attribute (predicate) value. RDF statements (triples) consist of subject, predicate and object which all are identified by URIs.

RDF uses VSAL

• variables can be used (blank nodes) http://www.w3.org/TR/rdf-primer/#structuredproperties

http://www.w3.org/TR/rdf-concepts/#dfn-blank-node

• sets of attributes cannot be defined in a single RDF triple, because attributes in RDF are represented as binary predicates only. However, it is possible to do that using RDF Container Elements (<rdf:Bag> and <rdf:Seq>) or RDF Collections. To define sets of attributes we create a new resource (which may either be a blank node or a resource with a URIref). The resource is given an rdf:type property whose value is one of the predefined resources rdf:Bag, rdf:Seq, or rdf:Alt . Then the members of the container can be described by defining a container membership property for each member with the container resource as its subject and the member as its object.

http://www.w3.org/TR/rdf-primer/#containers

Triples of the Data Model (an example from W3Schools.):

To avoid using URI all around we use namespaces which we define as follows: xmlns:si=„http://www.recshop.fake/siteinfo#”
In RDF/XML attributes (properties of subjects) can be defined in three ways

• Properties as XML elements

<?xml version="1.0"?>
 
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" <!-- rdf namespace -->
xmlns:si="http://www.recshop.fake/siteinfo#"><!-- other namespace (eg. Our own website's)>
  <rdf:Description rdf:about="http://www.w3schools.com/RDF"> <!-- subject identifed with a resource by rdf:about attribute -->
    <si:author>Jan Egil Refsnes</si:author> <!-- property and its value -->
    <si:homepage>http://www.w3schools.com</si:homepage> <!-- another property and its value -->
  </rdf:Description>
</rdf:RDF>

When you parse the example above with a RDF Validator, the result will look something like this

• Properties as attributes

• Properties as resources

(Z jakichś powodów nie mogę wkleić kodu - wyskakuje błąd o niezaimplementowanej funkcji POST…) — Weronika Furmańska 2008/05/21 18:31

http://w3schools.com/rdf/default.asp http://www.w3.org/TR/rdf-primer http://www.ninebynine.org/RDFNotes/RDFFactsAndRules.html#xtocid-7