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If we define element of student as an object, it not<br />

only has such attributes as name, score and student<br />

number, also contains attributes of course name, and<br />

name of element history is the value of course name<br />

attribute. In this situation, this element shows a king of<br />

character, its equivalent XML can be expressed as:<br />

<br />

<br />

B. Expressions of Conditional Semantic<br />

XML semantic expression is probable to have<br />

conditions which means if only satisfying certain<br />

condition, this element can express an example in some<br />

class or some attribute. The condition may be diverse,<br />

may be about attribute value or element character value,<br />

or about document framework, for example, some sub<br />

element is a must. For example:<br />

<br />

Among which, attribute of coltype is used to choose<br />

subclass of the college, object expressed by element<br />

college is sub-class practical example decided by the<br />

value of attribute of coltype.<br />

XML data attribute expression is probable to be<br />

conditional. For example,<br />

<br />

<br />

<br />

<br />

Among which, data attribute in element of Cigarette<br />

Property depends on the value of property Name node.<br />

Similarly, the expression of object attribute may be<br />

conditional.<br />

C.Expressions of Others<br />

In XML, document order contains important meaning;<br />

for example, in one language with XML to show<br />

structural data, nodes in the same name has different<br />

meaning in different positions.<br />

For example, a XML fragment expressing individual<br />

normal form [18]<br />

<br />

China<br />

Zhou Xiaqing<br />

605 East Road <br />

<br />

Among which, the first string fragment expresses<br />

attribute of state, and the second attribute of name.<br />

Besides, XML element may be divided into groups<br />

according to the attribute. Like:<br />

<br />

<br />

<br />

<br />

<br />

<br />

V.CONCLUSIONS<br />

This paper introduces the concept of semantics, then<br />

analyzes semantic expression way in the computer<br />

science and shows XML semantics is implicit, failure to<br />

express formalizing semantics. Finally, a model to<br />

express XML implicit semantics is put forward.<br />

Because the aim of XML Schema and DTD is to<br />

constraint XML document framework, and label and<br />

structure in XML document are not always just<br />

corresponding to the object and attribute. In addition,<br />

same XML structure may have many semantic<br />

explanations, such as nest structure, while XML Schema<br />

and DTD cannot distinct the possibilities clearly. As a<br />

result, to get the semantics automatically from XML<br />

document, XML Schema designers must be supposed to<br />

follow the thought of knowledge expression, designing<br />

XML document format in a normative way.<br />

Nevertheless, due to the diversity of XML implicit<br />

semantic expression way, this suppose seldom meets,<br />

which makes it very difficulty to get semantics<br />

automatically from XML document, so the further study<br />

in the future is necessary.<br />

REFERENCES<br />

[1] Tim Bray, Jean Paoli, C. M. Sperberg-Mc(aueen, and Eve<br />

Maler. Extensible markup language (xml) 1.0 (second<br />

edition) w3c recommendation, 6 October 2000<br />

[2] Liu SP, Lin ZQ, Mei J, Yue AB. A model-theoretic<br />

semantics for XML. Journal of Software, 2006,17(5):1089-<br />

1097..<br />

[3] Uschold M. Where are the semantics in the semantic Web.<br />

AI Magazine, 2003,24(3):25-36.<br />

[4] Berners-Lee T, Handler J, Lassila O. The semantic Web.<br />

Scientific American, 2001,184(5):34-43.<br />

[5] Amit Sheth, Robert Meersman. Amicalola Report:<br />

Database and Information Systems research Challenges<br />

and Opportunities in Semantic Web and Enterprises.<br />

SIGMOD Record Special Issue on Semantic Web,<br />

Database Management and Information Systems,<br />

December 2002.<br />

[6] Stefan Decker, Sergey Melnik, Frank Van Harmelen,<br />

Dieter Fensel, Michel Klein, Jeen Broekstra, Michael<br />

Erdmann, and Ian Horrocks. The semantic web: The roles<br />

of xml and rdf. IEEE Expert, 15(3), October 2000.<br />

[7] Michael Uschold. Where are the semantics in the semantic<br />

web AI Magazine,24(3):25-36, 2003.<br />

[8] Robert Worden. Mdl: a meaning definition language,<br />

version 2.06, 2002.<br />

[9] Denise Draper, Peter Fankhauser, Mary Fernrdez, Ashok<br />

Malhotra, Kristoffer Rose, Michael Rys, Jerome Simeon,<br />

and Philip Wadler. Xquery 1.0 and xpath 2.0 formal<br />

semantics, w3c working draft 20 February 2004.<br />

[10] Philip Wadler. A formal semantics of patterns in xslt and<br />

xpath. Markup Languages,2(2):183-202, 2000<br />

17

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