Joachim W. Schmidt

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For the extension of high level languages by data types of mode relation, three language constructs are proposed and discussed: a repetition statement controlled by relations, predicates as a generalization of Boolean expressions, and a constructor for relations using predicates. The language constructs are developed step by step starting with a set of(More)
We present a framework for the development of information systems based on the premise that the knowledge that influences the development process needs to somehow be captured, represented, and managed if the development process is to be rationalized. Experiences with a prototype environment developed in ESPRIT project DAIDA demonstrate the approach. The(More)
Increasing evidence suggests that forest soils in central and northern Europe as well as in North America have been significantly acidified by acid deposition during the last decades. The present investigation was undertaken to examine the effect of soil acidity on rooting patterns of 40-year-old Norway spruce trees by comparing fine and coarse roots among(More)
Scoping, naming and binding are central concepts in the deenition and understanding of programming languages. With the introduction of sophisticated data models, these issues become important for query languages as well. Additionally, the goal of integrating query and programming languages requires a common basis for their operational semantics. We ooer(More)
Based on the notion of persistent threads in Tycoon (Matthes and Schmidt, 1994), we investigate thread migration as a programming construct for building activity-oriented distributed applications. We first show how a straight-forward extension of a higher-order persistent language can be used to define activities that span multiple (semi-) autonomous nodes(More)
D ealing with change is one of the most fundamental challenges facing IS professionals today. Business process restructuring, shifting alliances and new competitors, deregulation and globalization, legacy system migration, and new technology adoption, are but a few of the economical, organizational, and technological forces contributing to the pervasiveness(More)
Focused views on entities of interest – concrete or abstract ones – are often represented by texts, images, speech or other media. Such media views are communicated through visual or audio channels and stored persistently in appropriate containers. In this paper we extend a computational content-container model into a closely coupled content-concept model(More)
Relational databases use predicates for a large variety of different functions. some leading to database search, others being handled by theorem proving. First we demonstrate that the theorem provinr! applications have very similar basic requirements for predicate manaeement but differ in their need foti efficiency. Second we Gresent dedicated deduction(More)