Подход к оценке сложности диаграмм SADT (IDEF0)

Abstract

SADT (Structured Analysis and Design Technique) methodology and its component IDEF0 is widely used for modeling business processes, software systems, as well as technology and production processes. There is a wide range of CASE-tools to implement SADT methodology. SADT-model construction starts with the presentation of a system as a single unit and arcs representing system interfaces with the environment. It is a so called contextual diagram. Then, this block is decomposed into several blocksjoined by arcs interface. These blocks are the original function subfunctions. Each of the sub-functions if necessary can be decomposed further in a similar manner to achieve the desired granularity. The paper offers a new approach to estimating the complexity of SADT models perception based on functioning features of short-term human memory and transferring data process from short-term memory into long-term. The article considers a model perception factor and a formula to calculate it which allows comparing and optimizing SADT models for a given parameter. The paper contains a perception factor analysis for a homogeneous SADT model (a model with the same number of blocks in all the diagrams). It confirms the known empirical principle: the number of diagram blocks should be in the range 3-6. An analysis of heterogeneous 2-level SADT model has shown that to reduce a perception factor, it is necessary to choose a decomposition strategy so that the number of blocks on the charts decreased when a decomposition level increases. The authors propose to use adaptable fuzzy systems for increasing the accuracy of estimating SADT models perception difficulty. Thus, a theoretical estimate of perception factor should be used as a priori information and experimental data as a training set.