Content markup language design principles

The research goal of this dissertation is to point the way towards a better understanding for the hidden complexities of knowledge communication and content markup, with a view to cleaner, more principled designs. The following four specific contributions are shown to be particularly useful tools in the quest for understanding and improving the design of content markup languages: Linguistics parallel. Since human language is a high-quality existing solution to a generalization of the problem that knowledge communication languages aim to solve, the study of the “engineering solutions” of human language provide a guideline to engineering solutions for content markup language design. Language layers and components. We propose a general architecture for knowledge communication languages, noting that human language appears to be structured in a deeply related parallel fashion. Compositionality. The Compositionality Principle is a fundamental research paradigm in the study of the semantics of human language. We show how this principle, which we have introduced into our research field from linguistics, has already had a notable effect on improving content markup languages. Categorial semantics. A categorial semantics of a knowledge communication language is another fundamental tool, as linguists who study the semantics of human language have discovered. In particular, we introduce the concept of categorial types into the discussion, and propose a complete categorial type system for one particular language, namely OpenMath. This dissertation is thus concerned with the architecture of such languages. The linguistics parallel posits a parallel between human language and content markup architectures based on a realization that the problems they solve are deeply related, which leads us to propose a general architecture of layers and components for content markup and knowledge communication languages. The compositionality principle provides an architectural guideline for the design of the two core layers of such languages, and writing a categorial type system for a compositional content markup language turns out to be an immensely useful tool for designing such a language. Application of this approach to several existing language proposals provides evidence for its practical usefulness, by showing how failure to adhere to these design principles produces concrete bugs in their specifications.