Lutz M. Wegner

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Making use of the fact that two-level grammars (TLGs) may be thought of as finite specification of context-free grammars (CFGs) with “infinite” sets of productions, known techniques for parsing CFGs are applied to TLGs by first specifying a canonical CFG G′ — called skeleton grammar — obtained from the “cross-reference” of the TLG G. Under very natural(More)
This paper introduces a visual interface for computer-supported cooperative work (CSCW). The interface is an extension of the editor interface of <sc>ESCHER</sc>, a prototype database system based on the extended non-first-normal-form data model. In <sc>ESCHER</sc>, the nested table approach is the paradigm for presenting data, where presenting includes(More)
We introduce ESCHER, a prototype database system based on the extended non-first-normal-form data model. The nested table approach is the paradigm for the graphical interface which allows browsing, editing and querying the database. Interaction is achieved by fingers generalizing the well-known cursor concept. We focus on interactive query formulation for(More)
Sorting, duplicate suppression and grouping are important operations in relational database management systems. This paper is devoted to the related language features and their implementation in the Advanced Information Management Prototype AIM-P. The query language HDBL is an SQL-like database language supporting the extended NF* data model. The proposed(More)
In a recent SIGMOD paper, Goyal et al. [7] asked whether GUI programming is a database research problem and answered it in the affirmative giving a solution based on logical programming. Here, we argue similarly in that GUI-related data should be removed from program code altogether and be placed into tables. To achieve the goal of shorter and more(More)