Relating knock-on viscosity to software modifiability

The notion of “cognitive dimensions” developed by Green provides an analytic framework for assessing usability for a variety of information artifacts. The work here describes formal interpretation of dimensions in order to precisely assess the suitability of interactive systems for particular tasks. The particular dimension considered is viscosity-this concerns the ease with which information structures can be modified and updated within a given environment. A formal interpretation of such a dimension has the benefit of yielding practical measures and guidelines for assessment. This extends a growing body of work concerned with formally characterising interactive properties that are significant to successful use. The context in which we demonstrate our interpretation of dimensions is that of program modification, where a program represents an information structure to be updated. The framework developed provides an interpretation of empirical evidence regarding software quality and modifiability