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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 />
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