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| '''Vivification''' is an operation on a [[description logic]] knowledge base to improve performance of a [[semantic reasoner]]. Vivification replaces a [[Logical disjunction|disjunction]] of concepts <math>C_1 \sqcup C_2 \ldots \sqcup C_n</math> by the ''least common subsumer'' of the concepts <math>C_1,C_2,\ldots C_n</math>. | | I'm Tyrell (30) from Venissieux, France. <br>I'm learning Japanese literature at a local university and I'm just about to graduate.<br>I have a part time job in a post office.<br><br>Here is my web page: [http://theminecraftsgame.com/profile/41295/bodozier backup plugin] |
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| The goal of this operation is to improve the performance of the reasoner by replacing a complex set of concepts with a single concept which subsumes the original concepts.
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| For example, consider the example given in (Cohen 92): Suppose we have the concept <math>\textrm{PIANIST(Jill)} \vee \textrm{ORGANIST(Jill)}</math>. This concept can be vivified into a simpler concept <math>\textrm{KEYBOARD-PLAYER(Jill)}</math>. This summarization leads to an approximation that may not be exactly equivalent to the original.
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| == An approximation ==
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| [[Knowledge base]] vivification is not necessarily exact. If the reasoner is operating under the [[open world assumption]] we may get surprising results. In the previous example, if we replace the disjunction with the vivified concept, we will arrive at a surprising results.
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| First, we find that the reasoner will no longer classify Jill as either a pianist or an organist. Even though <math>\textrm{ORGANIST}</math> and <math>\textrm{PIANIST}</math> are the only two sub-classes, under the OWA we can no longer classify Jill as playing one or the other. The reason is that there may be another keyboard instrument (e.g. a harpsichord) that Jill plays but which does not have a specific subclass.
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| == References ==
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| # Cohen, W.W., Borgida, A., Hirsh, H., Computing Least Common Subsumers in Description Logics, In: Proc. AAAI-92, AAAI Press/The MIT Press, 1992, pages 754--760. [http://citeseer.ist.psu.edu/cohen92computing.html CiteSeer]
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| # Baader, F., Kusters, R., Wolter F., Extensions to Description Logics. In F. Baader, D. Calvanese, D. McGuinness, D. Nardi, and P.F. Patel-Schneider, editors, The Description Logic Handbook: Theory, Implementation, and Applications. Cambridge University Press, 2003. http://citeseer.ist.psu.edu/baader03basic.html
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| {{Wikt|vivification}}
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| [[Category:Knowledge representation]]
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I'm Tyrell (30) from Venissieux, France.
I'm learning Japanese literature at a local university and I'm just about to graduate.
I have a part time job in a post office.
Here is my web page: backup plugin