**4. Conclusion**

92 Semantics – Advances in Theories and Mathematical Models

subsumption relationship. A well known technique named Tabulex provides structural subsumption of concepts. Description logic (DL) is assumed to be useful for semantic cache query processing and management (Ali et al. 2010). The relational queries can be modelled / translated in DL and DL inference algorithms can be used to find query containments. The translation of relational query to DL may have not the same spirit as that of querying languages for DL systems, but is sufficient for finding the query containment of relational queries (Ali et al. 2010). The subsumption reasoning (containment) of the semantics of the data to be cached is very useful in eliminating the redundant semantics and minimizing the

The tableaux algorithm (Baader et al., 1991a) (Hollunder et al., 1990) is instrumental to devise a reasoning service for knowledge base represented in description logic. All the facts of knowledge base are represented in a tree of branches with intra-branch logical AND between the facts and inter-branch logical OR, organized as per the rules of tableaux algorithm (Baader et al., 2003). A clash in a branch represents an inconsistency in that branch and the model in that branch can be discarded. The proof of subsumption or unsatisfiability can be obtained if all the models (all the branches) are discarded this way

The proposed solution (Ali et al. 2010) consists of two basic steps: First user query (relational) is translated into DL. The translated query is then evaluated for subsumption relationship with previously stored query in the cache by using the sound and complete

Considering, another scenario having predicates conditions with disjunctive operator in

clash. In second branch (Line 9 in Figure 10) *ename* and ⇁*ename* yields to clash, and in third *branch (Line 10* Figure 10), *≥30k(sal)* and *≤19k(sal)* yields to clash. All tree branches (Line 8, 9,

⊑

 *Q4;* therefore, *Q4* contain

⊑ *Q4.* 

*Emp* yields to

⇁

subsumption algorithm given in (Baader et al., 91b) (Lutz et al., 2005).

*Q3*. In first branch (Line 8 in Figure 10) after applying the *Or rule, Emp* and

10 of Figure 10) yield to clash in opening the tableaux algorithm; therefore, *Q3* 

Figure 10. All the three branches yields to clash in checking *Q3* 

Fig. 10. Query Containment using Tableux.

size of semantic cache for the same amount of data.

(Baader et al., 2003).

**3.7.1 Example** 

In this chapter we demonstrated several reasoning techniques of query processing in semantic cache. This chapter provides overview of semantic cache application in different domains such as relational databases, web queries, answering from views, xml based queries and description logic based queries.

Semantic cache query processing techniques are unstructured-semantics approaches, in which semantics are extracted from structured representations that have no semantics within their representations.
