Change - Semantic SeGarchp

Created on March 13, 2013, 8:21 a.m. by Hevok & updated on March 13, 2013, 8:33 a.m. by Hevok

In general the Interpoerability of Metadata should be achieved by the use of Ontologies. ¶
The Problem is among heterogenous Metadata there is a Semantic Gap. This Semantic Gap can be bridged with the Help of Ontologies. The Problem of the Semantic Gap means the different Ontologies can be applied to represent identical Knowledge. The Problem is how can one find ouppt that these different Ontologies really mean the same SThing or describe the same Thing. ¶
¶
Even cosidering a small world with three bricks in an initial state and one wnats to bring this bricks into a final state in the Wsame world, where all of these bricks stand one of Top of each other. ¶
¶
One can model this with some Objects (Block A, B and C as well as a Table and a hand that is able to grab these Objects). Then one has several Relations, for example there is the on Relation that says a block stands on top of another block. There is a clear Relation that means if we have a block in the hend we clear it. The block is hold with the holding Relation. Lastly one cna ask whether the hand is empty or not. With this modeling one is able to bring the world from its initial state to the final state of the world. ¶
¶
Tis is however not the only way to model this. Another approach is with less objects, namley one Block A, B and C. So here we do notneed the table nor the hand, but therefore we have other kind of relations. In addition to the on, clear, hlding and handEmpty Relation there is instead of defining a table a Relation that a Block X stands on a table (which is other true or not true). ¶
¶
To model this in kind of a represential Tree one has Entity and Relation Classes. There one has Entity Table, block and hand. Beloning to them there is a table T, Blocks A,B and C as well as hand H. The Relations can be binary, unary or even have no arguments like handEmpy which gives back a boolean (True or False). The World can also be described with the help of Axioms where one says if X stands on Y and Y stands on Z than X is above Z for example. ¶
¶
In the other model one has only one type of Exntity, namely block which contains Block A, B and C. There are also Relations with an additional unary Relation onTable. ¶
¶
The problem is that one has two different models, but from the tree represention they are quite similiar. We can identify in these trees which has the same Meaning or does represent the same as in the other tree. So one can define Mappings. One has to do this because one wants to find out whether this two Models really denote the same. To brigth this we need an Ontology representation that is able to map one model into another Model. One has to understand this Model. ¶
¶
The Semantic Web is based on interoerability of Metadata ¶
Among heterogenous Metadata there is a Semantic Gap that can be bridged with the help of Ontologies ¶
¶
- Proble of the Semantic Gap: ¶
+ differnt Ontologies can be applied to represent identical Knowledge. ¶
¶
Let's Model a world: ¶
¶
- Models: ¶
¶
Objects Relations Objects Relations ¶
block A on(X,Y) block A on(X,Y) ¶
block B clear(X,Y) block B clear(X) ¶
block C holding(X) block C onTable(X) ¶
table T handEmpty holding(X) ¶
hand H handEmpty ¶
¶
- Axoim: on(X,Y) ⋀ on(Y,Z) → above(X,Y) ¶
¶
behind the Model there is an Ontology ¶