Browsing by Author "Liu, Mengchi"
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- ItemOpen AccessDECLARATIVE UPDATES IN DEDUCTIVE DATABASES(1993-01-01) Cleary, John; Liu, MengchiThis paper proposes an update language called Datalog/UT which extends Datalog by incorporating update rules with temporal information. Programs to update example Databases are given. The semantics of Datalog/UT are described. Datalog/UT has a declarative semantics using local stratification which is a natural and direct extension of the traditional Datalog semantics and reduces to it in the special case. This is achieved by using explicit temporal information to control the update operations implicitly.
- ItemOpen AccessDECLARATIVE UPDATES IN DEDUCTIVE OBJECT BASES(1993-03-01) Cleary, John; Liu, MengchiUpdates are important database operations, but there has not yet been a uniform logical framework that accounts for them. This paper presents an approach to deal with updates in the deductive and object-oriented database setting. It incorporates temporal information into update rules, so that different versions of objects may be created at different time points and can be identified by the temporal information. The proposed update language has a simple and clear Herbrand-like declarative semantics, which can be computed by a bottom-up evaluation using a temporal stratification.
- ItemOpen AccessDEDUCTIVE DATABASES - WHERE TO NOW?(1990-01-01) Cleary, John; Liu, MengchiDeductive databases result from the integration of relational database and logic programming techniques. It combines the benefits of these two approaches, such as representational and operational uniformity, deductive power, efficient secondary storage access, etc. However, significant problems remain inherent in this synthesis. There are three broad areas where problems are apparent. The first problem area is how to naturally represent objects, complex objects and inheritance information. The second problem area is how to naturally deal with higher-order features in deductive databases. The last is the area of updates. The paper discusses these problems, surveys some of the attempts that have been made towards solving these problems and prepares an integrated framework for solving them.
- ItemOpen AccessNLO: a deductive object base language(1992) Liu, Mengchi; Gaines, Brian R.
- ItemOpen AccessS-logic: a higher order logic for deductive databases(1990) Liu, Mengchi; Cleary, John G.
- ItemOpen AccessS-LOGIC: A HIGHER-ORDER LOGIC LANGUAGE FOR DEDUCTIVE DATABASES(1990-02-01) Cleary, John; Liu, MengchiDeductive databases based on relational databases and Prolog techniques are not suitable for complex object modeling. The problems result from the underlying relational model and the pure Prolog which use inexpressive flat structures. Semantic data models using data abstractions and inheritance greatly increase expressiveness. So do extended terms with internal structure in logic programming. This paper proposes a higher-order logic language for deductive databases called S-logic which is the combination of the semantic data model and extended term approaches. It supports object identity, semantic data abstractions and inheritance very naturally and allows the definition and manipulation of database schema and data in an integrated framework.