Abstract

Forward computation of dynamic slices is necessary to support interactive debugging and online analysis of long running programs. However, the overhead of existing forward computing algorithms limits their use to nonprocessing intensive applications. Recent empirical studies have shown that slices tend to reoccur often during execution. This paper presents a new forward computing algorithm for dynamic slicing, which is based on the stronger assumption that the same set union operations need to be performed repeatedly during slice computation. We present the results of an empirical study contrasting the performance of our new algorithm to the performance of a basic forward computing algorithm that unconditionally merges slices influencing an executing statement. The results indicate that the new algorithm is substantially faster than the basic algorithm and often requires significantly less memory.

The best lower bound known on the crossing number of the complete bipartite graph is : $$cr(K_{m,n}) \geq (1/5)(m)(m-1)\lfloor n/2 \rfloor \lfloor(n-1)/2\rfloor$$ In this paper we prove that: $$cr(K_{m,n}) \geq (1/5)m(m-1)\lfloor n/2 \rfloor \lfloor (n-1)/2 \rfloor + 9.9 \times 10^{-6} m^2n^2$$ for sufficiently large $m$ and $n$.

Developing dependable software systems requires enforcing conformance between architecture and implementation during software development and evolution. We address this problem with a multi-pronged approach: (a) automated refinement of a component-and-connector (C&C) architectural view into an initial implementation, (b) enforcement of architectural structure at the programming language level, (c) automated abstraction of a C&C view from an implementation, and (d) semi-automated incremental synchronization between the architectural and the implementation C&C views.We use an Architecture Description Language (ADL), Acme, to describe the architecture, and ArchJava, an implementation language which embeds a C&C architecture specification within Java implementation code. Although both Acme and ArchJava specify C&C views, a number of structural differences may arise. Our approach can detect structural differences which correspond directly to implementation-level violations of the well thoughtout architectural intent. Furthermore, supplementing the C&C view extracted from the implementation with architectural types and styles can uncover additional violations.

We demonstrate a tool to incrementally synchronize an Acme architectural model described in the Acme Architectural Description Language (ADL) with an implementation in ArchJava, an extension of the Java programming language that includes explicit architectural modeling constructs.