As the tableau algorithm would produce a lot of description overlaps when judging the satisfiabilities of concepts（thus wasting much space）,a clause-based enhancing mode designed for the language ALCN is proposed.Th...As the tableau algorithm would produce a lot of description overlaps when judging the satisfiabilities of concepts（thus wasting much space）,a clause-based enhancing mode designed for the language ALCN is proposed.This enhancing mode constructs a disjunctive normal form on concept expressions and keeps only one conjunctive clause,and then substitutes the obtained succinctest conjunctive clause for sub-concepts set in the labeling of nodes of a completion tree constructed by the tableau algorithm （such a process may be repeated as many times as needed）.Due to the avoidance of tremendous descriptions redundancies caused by applying ∩- and ∪-rules of the ordinary tableau algorithm,this mode greatly improves the spatial performance as a result.An example is given to demonstrate the application of this enhancing mode and its reduction in the cost of space. Results show that the improvement is very outstanding.展开更多
To enable the representation and reasoning for fuzzy ontologies with expressive fuzzy knowledge on the semantic web, a new fuzzy extension of description logics called vague ALC which is based on vague sets is present...To enable the representation and reasoning for fuzzy ontologies with expressive fuzzy knowledge on the semantic web, a new fuzzy extension of description logics called vague ALC which is based on vague sets is presented. The definition of vague set is introduced and then the syntax and semantics of vague ALC are formally defined. The forms of axioms and assertions in the vague ALC knowledge bases are specified. Finally, the tableau algorithm is developed for the reasoning in the vague ALC. The vague ALC based on vague set uses two degrees of membership instead of a single membership degree in the fuzzy sets and is more accurate in representing the imprecision in the degrees of membership. The vague ALC has more expressive power than ALC and can represent fuzzy knowledge and perform reasoning tasks based on them. Therefore, the vague ALC can enable the representation and reasoning for fuzzy ontologies with expressive fuzzy knowledge on the semantic web.展开更多
基金The National Natural Science Foundation of China(No.60775029)the Science and Technology Program of Zhejiang Province(No.2007C33072)
文摘As the tableau algorithm would produce a lot of description overlaps when judging the satisfiabilities of concepts（thus wasting much space）,a clause-based enhancing mode designed for the language ALCN is proposed.This enhancing mode constructs a disjunctive normal form on concept expressions and keeps only one conjunctive clause,and then substitutes the obtained succinctest conjunctive clause for sub-concepts set in the labeling of nodes of a completion tree constructed by the tableau algorithm （such a process may be repeated as many times as needed）.Due to the avoidance of tremendous descriptions redundancies caused by applying ∩- and ∪-rules of the ordinary tableau algorithm,this mode greatly improves the spatial performance as a result.An example is given to demonstrate the application of this enhancing mode and its reduction in the cost of space. Results show that the improvement is very outstanding.
基金Program for New Century Excellent Talents in Uni-versity (NoNCET-05-0288)
文摘To enable the representation and reasoning for fuzzy ontologies with expressive fuzzy knowledge on the semantic web, a new fuzzy extension of description logics called vague ALC which is based on vague sets is presented. The definition of vague set is introduced and then the syntax and semantics of vague ALC are formally defined. The forms of axioms and assertions in the vague ALC knowledge bases are specified. Finally, the tableau algorithm is developed for the reasoning in the vague ALC. The vague ALC based on vague set uses two degrees of membership instead of a single membership degree in the fuzzy sets and is more accurate in representing the imprecision in the degrees of membership. The vague ALC has more expressive power than ALC and can represent fuzzy knowledge and perform reasoning tasks based on them. Therefore, the vague ALC can enable the representation and reasoning for fuzzy ontologies with expressive fuzzy knowledge on the semantic web.
