Slicing techniques can provide solutions to many software engineering problems such as testing, program understanding and extraction of a reusable component. However, current slicing criteria and the corresponding techniques might obtain slices that contain unnecessary statements in some situations. In this paper, we propose a new slicing technique that takes the specification of the slice into account. The information present in the specification helps to produce more precise slices by removing statements that are not relevant to the specification for the slice. Our technique is based on the weakest precondition and strongest postcondition. We present an example of applying the proposed technique in extracting a reusable component from an existing program.

Software restructuring is recognized as a promising method to improve logical structure and understandability of a software system which is composed of modules with loosely-coupled elements. In this paper, we present methods of restructuring an ill-structured module at the software maintenance phase. The methods identify modules performing multiple functions and restructure such modules. For identifying the multi-function modules, the notion of the tightly-coupled module that performs a single specific function is formalized. This method utilizes information on data and control dependence, and applies program slicing to carry out the task of extracting the tightly-coupled modules from the multi-function module. The identified multi-function module is restructured into a number of functional strength modules or an informational strength module. The module strength is used as a criterion to decide how to restructure. The proposed methods can be readily automated and incorporated in a software tool.

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