This paper presents a new method of page segmentation based on the analysis of background (white areas). The proposed method is capable of segmenting pages with non-rectangular layout as well as with various angles of skew. The characteristics of the method are as follows: (1) thinning of the background enables us to represent white areas of any shape as connected thin lines or chains and the robustness for tilted page images is also achieved by the representation; and (2) based on this representation, the task of page segmentation is defined as to find the loops enclosing printed areas. The task is achieved by eliminating unnecessary chains using not only a feature of white areas, but also a feature of black areas divided by a chain. Based on the experimental results and the comparison with previous methods, we discuss the advantages and limitations of the proposed method.

A conceptual diagram is a kind of diagram which represents a logical structure among concepts using simple physical objects (loops, lines and character strings). This paper presents a method of interpretation of conceptual diagrams. In conceptual diagrams, a single physical object plays various logical roles depending on surrounding physical objects, because there are no specific ruled of writing conceptual diagrams. To cope with this problem, we introduce the strategy of hypothesis generation and verification; hypothesized interpretations are verified by relaxation which takes account of logical relations to other physical objects. From the experimental results using 50 conceptual diagrams, we discuss the effectiveness of our method.

A method of semiautomatic specification refinement and program generation using library modules, is described. Users write their specifications and modify and rearrange them so that they can be refined with the aid of the library modules. When a specification is given, a refinement system, called MAPS (module-aided program construction system) searches for library modules applicable to the given specification, replaces the specification with a more detailed description written in the operation part of the modules, and converts the refined specification into a program written in a programming language designated by the user. Case-like expressions or pseudo-natural language expressions are used for describing user's specifications and specifications for library modules.>