The 28th International Workshop on Qualitative Reasoning (QR-15) presented advances toward reasoning tractably with massive qualitative and quantitative models, automatically learning and reasoning about continuous processes, and representing knowledge about space, causation, and uncertainty. The technical track included two invited talks, 11 oral presentations, and 5 poster presentations.

The Eighth International Workshop on Qualitative Reasoning about Physical Systems (QR '94) was held on 7-10 June 1994 in Nara, Japan. Fifty-three people participated, and 34 papers were presented in either oral or poster sessions. The papers either addressed core issues of qualitative reasoning or extended the field along three axes: (1) cognitive modeling, (2) mathematical sophistication, and (3) application. Mita's selfmaintenance copier and IBM's mechanism design and analysis using configuration spaces were demonstrated, convincing the participants of the promising role of qualitative-reasoning techniques in engineering and manufacturing domains. Since the first workshop in 1987, the workshop site has altered between the United States and Europe.

Articulating thought in computerbased media is a powerful means for humans to develop their understanding of phenomena. We have created DynaLearn, an intelligent learning environment that allows learners to acquire conceptual knowledge by constructing and simulating qualitative models of how systems behave. DynaLearn uses diagrammatic representations for learners to express their ideas. The environment is equipped with semantic technology components that are capable of generating knowledge-based feedback and virtual characters that enhance the interaction with learners. Teachers have created course material, and successful evaluation studies have been performed.

The traditional reliability design methods are imperfect because the designed systems aim at fewer faults, but once a fault happens, the systems might hard fail. To solve this problem, we present a self-maintenance machine (SMM), one that can maintain its functions flexibly even though faults occur. To achieve the capabilities of diagnosing and repair planning, a model-based approach that uses qualitative physics was proposed. Regarding the repair-executing capability, a control-type repair strategy was followed. A prototype of the SMM was developed, and it succeeded in maintaining its functions if the structure did not change.

In this editorial introduction to this special issue of AI Magazine on qualitative reasoning, we briefly discuss the main motivations and characteristics of this branch of AI research. We also summarize the contributions in this issue and point out challenges for future research. Successful application areas include autonomous spacecraft support, failure analysis and on-board diagnosis of vehicle systems, automated generation of control software for photocopiers, and intelligent aids for learning about thermodynamic cycles. Qualitative reasoning is thus relevant for researchers who are interested in important AI issues as well as for managers, developers, and engineers who are looking for potential industrial benefits of AI. A decade has passed since the publication of three collections of papers and a book covering the foundations of the field (Weld and de Kleer 1990), the status at that time (Faltings and Struss 1992; Williams and de Kleer 1991), and a comprehensive treatment of qualitative simulation (Kuipers 1994).

A common difficulty in diagnosing failures within Pratt & Whitney's F100-PW-100/200 gas turbine engine occurs when a fault in one part of a system--comprising an engine, an airframe, a test cell, and automated ground engine test set (AGETS) equipment--is manifested as an out-ofbound parameter elsewhere in the system. In such cases, the normal procedure is to run AGETS self-diagnostics on the abnormal parameter. However, because the self-diagnostics only test the specified local parameter, it will pass, leaving only the operators' experience and traditional fault-isolation manuals to locate the source of the problem in another part of the system. In such cases, the normal procedure is to run AGETS self-diagnostics on the abnormal parameter. However, because the self-diagnostics only test the parameter specified, it will pass because parameter tests are local tests that cannot uncover malfunctions in other parts of the system.

The AAAI-90 Workshop on Qualitative Vision was held on Sunday, 29 July 1990. Over 50 researchers from North America, Europe, and Japan attended the workshop. This article contains a report of the workshop presentations and discussions. The AAAI-90 Workshop on Qualitative Vision was organized into seven sessions, with each session focusing on a specific topic. The first session was on the approaches and psychophysical bases of qualitative vision, addressing the question of what is qualitative vision.

This page includes forthcoming AAAI sponsored conferences, conferences presented by AAAI Affiliates, and conferences held in cooperation with AAAI. AI Magazine also maintains a calendar listing that includes nonaffiliated conferences at www.aaai.org/Magazine/calendar.php. HCOMP 2015 will be held November 8-11 in San Diego, California. The AAAI Fall Symposium Series will be held November 12-14 in Arlington, Virginia USA. AIIDE-14 will be held November 14-18 in Santa Cruz, California USA.

This page includes forthcoming AAAI sponsored conferences, conferences presented by AAAI Affiliates, and conferences held in cooperation with AAAI. AI Magazine also maintains a calendar listing that includes nonaffiliated conferences at www.aaai.org/Magazine/calendar.php. The AAAI Spring Symposium Series will be held March 23-25 in Palo Alto, CA USA. ICWSM 2015 will be held May 26-29 in Oxford, UK. The AAAI Fall Symposium Series will be held November 12-14 in in Arlington, Virginia USA.

This page includes forthcoming AAAI sponsored conferences, conferences presented by AAAI Affiliates, and conferences held in cooperation with AAAI. AI Magazine also maintains a calendar listing that includes nonaffiliated conferences at www.aaai.org/Magazine/calendar.php. AAAI-15 will be held January 25-30 in Austin, Texas, USA. The AAAI Spring Symposium Series will be held March 23-25 in Palo Alto, CA USA. ICWSM 2015 will be held May 26-29 in Oxford, UK.