Declarative picture description and interpretation in logic
Hong Zhi Gao · 1992
The importance of picture description has been widely recognized, especially in graphical user interface construction and electronic document preparation. This dissertation presents a logic framework for picture description and picture generation. The key issue of a picture description language is the specification of the hierarchical composition of a picture and relationships among its sub-pictures. To address this, we propose the use of constraint-based, definite clause logic, which is a subset of first-order logic, as a declarative, user-friendly picture description language. The declarative and abstract operational semantics of this are defined in the abductive logic programming framework, which is a general logic framework that includes constraint logic programming as a special case. Since picture descriptions are viewed as general abductive logic programs, in the dissertation we develop a resolution strategy (AOLDTNF) for abductive logic programs based on the OLDT resolution strategy. OLDT is different from Prolog's SLD and terminates more logically meaningful Horn clause programs than SLD. By treating constraint predicates defined in a computation domain with a complete theory specially, AOLDTNF is refined to a more efficient evaluation strategy, OLDTC. By incorporating certain answer manipulations into OLDTC, such as answer projection and answer merging, OLDTC is extended to a more powerful evaluation strategy OLDTC-AM. In many picture description applications, optimization techniques and hierarchical constraint programming are needed. In the dissertation, we study both of them and define their respective logical semantics based on the OLDTC-AM evaluation strategy. For an optimization problem, we propose how to represent it logically and solve it simply in the constraint logic programming paradigm. For a hierarchical constraint problem, we propose how to turn it into an optimization problem and evaluate it in the constraint logic programming paradigm. In addition to the above theoretical discussions, in the dissertation we also give two practical picture description examples and describe a prototype picture generation system developed at Stony Brook. The prototype system is built on the X Window system through ProXL, which is an interface between the Quintus Prolog system and the X Window system. Finally we conclude with the main results in this dissertation.