Pictorial representations significantly enhance our ability to understand complicated relations and structures, which means that information systems strongly require user interfaces that support the visualization of many kinds of information with a wide variety of graphical forms. At present, however, these difficult visualization problems have not been solved. We present a visualization framework for translating abstract objects and relations, typically represented in textual forms, into pictorial representations, and describe a general visualization interface based on this framework. In our framework, abstract objects and relations are mapped to graphical objects and relations by user-defined mapping rules. The kernel of our visualization process is to determine a layout of graphical objects under geometric constraints. A constraint-based object layout system named COOL has been developed to handle this layout problem. COOL introduces the concept of rigidity of constraints in order to reasonably handle, a set of conflicting constraints by use of the least squares method. As applications of our system, we show the generation of kinship diagrams, list diagrams, Nassi-Shneiderman diagrams, and entity-relationship diagrams.

When Object-Oriented languages are applied to distributed problem solving, the form of communication restricted to direct message sending is not flexible enough to naturally express complex interactions among the objects. We transformed the Tuple Space Communication Model[29] for better affinity with Object-Oriented computation, and integrated it as an alternative method of communication among the distributed objects. To avoid the danger of potential bottleneck, we formulated an algorithm that makes concurrent pattern matching activities within the Tuple Space possible.

A new display scheme is presented in which three-dimensional objects are represented with a much higher degree of user control of the line-drawing format than those in conventional schemes. In this scheme, the attribute of a line is determined not at the time of definition but after the viewing transformation has been applied, taking the shielding environment of the line into consideration. The essential difference between our scheme and conventional hidden-line removal/indication lies in the treatment of the shielding environment. In conventional hidden-line removal/indication, only the visible/invisible information is available for the selection of the attribute of a line. In our scheme, the entire set of surfaces that hide a line can be used to determine the attribute of the line. A much higher degree of freedom in generating pictures is achieved owing to the treatment of the shielding environment. We also describe a system called GRIP, which implements the new scheme.

Abstract A simple block structure (called semiblock) suitable for low‐level languages is presented. This is not a language but a structure, and preserves the high efficiency of the programs written in the ‘host’ languages. The structure offers the localization of label scopes and the capability of constructing control structures such as selection and repetition. The self‐documentability of programs can be increased by the use of Algol‐like formatting of source texts, which the proposed structure allows and encourages the users to use. The relation between the proposed structure and a simple macro facility is discussed.

Abstract A segmentation scheme for ALGOL‐like programs is presented. This scheme, based on the separate compilation facility of the language ALGOL 68C, enables the programmers to use a branch‐and‐merge (lattice) structure in segmenting their programs, besides the tree which is the only one structure usable in ALGOL 68C programming. The necessity of this scheme is explained and the way of its implementation is described. The effectiveness of this scheme compared with tree structure segmentation is shown in terms of the recompilation cost of an example program of reasonably large size which has been resegmented from the tree to the lattice structure with no addition or duplication of codes.