Dimensions of consistency in source versions and system compositions

In building systems there are various levels at which we consider the problems reasoning about consistency and it means different things at those various levels. At the version management level, consistency means what it does in databases: no data is lost due to concurrency problems (eg, race conditions). At the composition and substitution (or creation and evolution) levels it means something that is significantly different--- namely, the syntactic and semantic consistency of the various pieces that make up the system. I first address the issue of what makes a system composition well-formed both syntactically and semantically. I then address the issue of substitution in well-formed system compositions, first in the context of simple substitution and then in the context of compound substitution (that is, the simultaneous substitution of multiple components). Note: This paper derived and extended from papers: the well-formed system composition paper [9] was published only as a technical report at CMU (though variously used without references or with misleading ones) the version control paper from ICSE9 [16], the extended abstract for SCM3 [19], and the shared dependency paper from SCM6 [20] all of which have been published only in conference or workshop versions. There may be parts of the other Inscape papers (ICSE9 [15], ICSE11 [17], and TAV3 [18]) included as well- all of which have been published only in conference versions

Research summary, January 1989 - June 1990

The Research Institute for Advanced Computer Science (RIACS) was established at NASA ARC in June of 1983. RIACS is privately operated by the Universities Space Research Association (USRA), a consortium of 62 universities with graduate programs in the aerospace sciences, under a Cooperative Agreement with NASA. RIACS serves as the representative of the USRA universities at ARC. This document reports our activities and accomplishments for the period 1 Jan. 1989 - 30 Jun. 1990. The following topics are covered: learning systems, networked systems, and parallel systems

NuzzleBug: Debugging Block-Based Programs in Scratch

While professional integrated programming environments support developers with advanced debugging functionality, block-based programming environments for young learners often provide no support for debugging at all, thus inhibiting debugging and preventing debugging education. In this paper we introduce NuzzleBug, an extension of the popular block-based programming environment Scratch that provides the missing debugging support. NuzzleBug allows controlling the executions of Scratch programs with classical debugging functionality such as stepping and breakpoints, and it is an omniscient debugger that also allows reverse stepping. To support learners in deriving hypotheses that guide debugging, NuzzleBug is an interrogative debugger that enables to ask questions about executions and provides answers explaining the behavior in question. In order to evaluate NuzzleBug, we survey the opinions of teachers, and study the effects on learners in terms of debugging effectiveness and efficiency. We find that teachers consider NuzzleBug to be useful, and children can use it to debug faulty programs effectively. However, systematic debugging requires dedicated training, and even when NuzzleBug can provide correct answers learners may require further help to comprehend faults and necessary fixes, thus calling for further research on improving debugging techniques and the information they provide.Comment: To appear at the 2024 IEEE/ACM 46th International Conference on Software Engineering (ICSE '24), April 14--20, 2024, Lisbon, Portuga

A Chronicle of the Kentucky Transportation Research Program

The basis for the Kentucky Transportation Research Program (KTRP) was established more than 45 years ago and some of the current staff members have over 35 years experience in transportation research. Over the years, principal investigators have developed expertise in major areas of transportation and have made significant contributions in highway safety, pavement design and performance, embankment analyses, fatigue detection in bridges, noise abatement, traffic control and operations, voidless concrete, pavement texture and skid resistance, structural design and analyses of culverts, traffic forecasting, and numerous other areas. The Transportation Research Building houses several fully equipped laboratories. Special effort was made to provide flexibility and versatility in the arrangement of fixtures in the various laboratories. Computer services are available through the University of Kentucky and a full-time programming staff capable of summarizing, analyzing, and plotting data is available to all researchers. The Program also maintains a collection of current periodicals and publications from other transportation research organizations. Appreciable acceptance of study findings and resultant implementation of study recommendations has led to significant benefit-cost ratios for many studies undertaken by the unit. Values derived from research have been demonstrated routinely