Nonunique Naming Assumption

Open versus Closed world assumption. The openness of the Web, described by the AAA Slogan, has additional implications on Semantic Web applications beyond the Nonunique Naming Assumption discussed in Sect. 3.4.1. With respect to reasoning, Semantic Web systems are built on the assumption that the system has incomplete information and therefore adopt an Open World Assumption (OWA). Under the OWA, information that is not explicitly stated is considered unknown rather than false. For example, asking whether mo Engl has Ford as a supplier, will not return No, but an empty value set. By contrast, database systems operate under a Closed World Assumption (CWA) and therefore assume complete information. In other words, information that is not known is considered false. The same query as above will return No as a result under CWA. 

Semantic Web technologies have been designed to comply with the open nature of the Web captured by the Anyone is allowed to say Anything about Any topic slogan (Allemang and Hendler 2011). Some implications of this compliance are the Nonunique Naming Assumption (Sect. 3.4.1) and the Open World Assumption (Sect. 3.5). 

In the Semantic Web, the tasks of (i) validating RDF data against a set of integrity constraints and (ii) performing RDFS/OWL reasoning, are grounded on different semantics. While the latter operates under the Open World Assumption (OWA) (i.e., a statement cannot be assumed to be false if it cannot be proven to be true) and the Nonunique Name Assumption (nUNA) (i.e., the same object/resource can have... 

This fact allows us to choose properly a frequency for a given probe. As is well known, with an increase of frequency the vertical response of the probe becomes better, and we can measure higher resistivities of a formation. However, if the frequency is chosen too high at least two problems arise, namely nonuniqueness in determination of resistivity by measuring the quadrature component of the field, and the radial response can be significantly worse than that calculated with the assumption that the skin effect is negligible. Comparison of calculated results, based on exact and approximate solutions, defines the maximal frequency for which the skin effect is still absent in the borehole and the invasion zone but in the formation it manifests itself in the same manner as in a uniform medium with the same resistivity. 

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