Concepts of relevance in a semiotic framework applied to ISAD (information systems analysis and design).

Relevance is the critical criterion for valuing information. The usual requirements of valuable information resources are their accuracy, brevity, timeliness and rarity. This thesis points out that relevance has to be explicitly recognised as an important quality of information. Therefore, the theory of signs is adopted to enable a systematic study of the problem of relevance according to the branches of semiotics in order to clarify the concept of information. Relevance has several meanings according to the various disciplinary approaches including phenomenology, law, logic, information science, communication and cognition. These different concepts are discussed and criticised in two chapters. A new approach is proposed in which a universal concept of relevance is considered as an affordance. Therefore, all the approaches to relevance can be applied within the broader approach of the analysis of affordances. This approach not only encompasses all the underlying characteristics of relevance, it is also compatible with the assumptions of the logic of norms and affordances (NORMA). NORMA semantic analysis is used as a basis on which concepts of relevance are applied semiotically. Two case- studies are selected for testing these concepts which results in a guideline for practical application in a semiotic framework. The results from these case-studies confirm the practical importance of these concepts of relevance which can be systematically used in the analysis and design of information systems. It also reaffirms the underlying characteristics of relevance which exist in the context of social reality