9507980
Using build-integrated static checking to preserve correctness invariants
A key missing link in the creation of secure and robust systems is finding a ost effective way to demonstrate and preserve correspondence between a software design and its implementation. This paper explores the use of software model checking techniques to validate selected design invariants in the EROS operating system kernel. Several global consistency policies in the EROS kernel can be expressed as finite state automata. Using the MOPS static hecker, we have been able to validate the EROS kernel implementation against these automata. In the process, we have confirmed the practical utility of the basic verification technique, identified a number of desirable enhancements in MOPS, and located bugs in the EROS implementation.
 A key contribution of this paper is establishing that it is practical to integrate software model checking into normal development lifestyle. Model hecking is efficient enough that it does not add noticeably to our build times. This allows us to view it as a tool for error prevention rather than <i>detection</i>. Our work with EROS and MOPS suggests that domain specific application of software model hecking is a practical and powerful technique for software assurance and maintenance.
1402963
MOPS: an infrastructure for examining security properties of software
We describe a formal approach for finding bugs in security-relevant software and verifying their absence. The idea is as follows: we identify rules of safe programming practice, encode them as safety properties, and verify whether these properties are obeyed. Because manual verification is too expensive, we have built a program analysis tool to automate this process. Our program analysis models the program to be verified as a pushdown automaton, represents the security property as a finite state automaton, and uses model checking techniques to identify whether any state violating the desired security goal is reachable in the program. The major advantages of this approach are that it is sound in verifying the absence of certain classes of vulnerabilities, that it is fully interprocedural, and that it is efficient and scalable. Experience suggests that this approach will be useful in finding a wide range of security vulnerabilities in large programs efficiently.
9276534
Setuid Demystified
1567676
Bringing order to the Web: automatically categorizing search results
We developed a user interface that organizes Web search results into hierarchical categories. Text classification algorithms were used to automatically classify arbitrary search results into an existing category structure on-the-fly. A user study compared our new category interface with the typical ranked list interface of search results. The study showed that the category interface is superior both in objective and subjective measures. Subjects liked the category interface much better than the list interface, and they were 50% faster at finding information that was organized into categories. Organizing search results allows users to focus on items in categories of interest rather than having to browse through all the results sequentially.
1194024
Hierarchical classification of Web content
This paper explores the use of hierarchical structure for classifying a large, heterogeneous collection of web content. The hierarchical structure is initially used to train different second-level classifiers. In the hierarchical case, a model is learned to distinguish a second-level category from other categories within the same top level. In the flat non-hierarchical case, a model distinguishes a second-level category from all other second-level categories. Scoring rules can further take advantage of the hierarchy by considering only second-level categories that exceed a threshold at the top level.
We use support vector machine (SVM) classifiers, which have been shown to be efficient and effective for classification, but not previously explored in the context of hierarchical classification. We found small advantages in accuracy for hierarchical models over flat models. For the hierarchical approach, we found the same accuracy using a sequential Boolean decision rule and a multiplicative decision rule. Since the sequential approach is much more efficient, requiring only 14%-16% of the comparisons used in the other approaches, we find it to be a good choice for classifying text into large hierarchical structures.
14045822
Optimizing search by showing results in context
We developed and evaluated seven interfaces for integrating semantic category information with Web search results. List interfaces were based on the familiar ranked-listing of search results, sometimes augmented with a category name for each result. Category interfaces also showed page titles and/or category names, but re-organized the search results so that items in the same category were grouped together visually. Our user studies show that all Category interfaces were more effective than List interfaces even when lists were augmented with category names for each result. The best category performance was obtained when both category names and individual page titles were presented. Either alone is better than a list presentation, but both together provide the most effective means for allowing users to quickly examining search results. These results provide a better understanding of the perceptual and cognitive factors underlying the advantage of category groupings and provide some practical guidance to Web search interface designers.
32790214
Federating Diverse Collections of Scientific Literature
The Digital Library Initiative (DLI) project at the University of Illinois at Urbana-Champaign is developing the information infrastructure to effectively search technical documents on the Internet. The authors are constructing a large testbed of scientific literature, evaluating its effectiveness under significant use, and researching enhanced search technology. They are building repositories (organized collections) of indexed multiple-source collections and federating (merging and mapping) them by searching the material via multiple views of a single virtual collection. Developing widely usable Web technology is also a key goal. Improving Web search beyond full-text retrieval will require using document structure in the short term and document semantics in the long term. Their testbed efforts concentrate on journal articles from the scientific literature, with structure specified by the Standard Generalized Markup Language (SGML). Research efforts extract semantics from documents using the scalable technology of concept spaces based on context frequency. They then merge these efforts with traditional library indexing to provide a single Internet interface to indexes of multiple repositories.
30643736
Compound Brushing Explained†
This paper proposes a conceptual model called compound brushing for modeling the brushing techniques used in dynamic data visualization. In this approach, brushing techniques are modeled as higraphs with five types of basic entities: data, selection, device, renderer, and transformation. Using this model, a flexible visual programming tool is designed not only to configure and control various common types of brushing techniques currently used in dynamic data visualization but also to investigate new brushing techniques.
3121075
Parameterized Compilability
Compilability is a measure of how effectively compilation (or preprocessing) can be applied to knowledge bases specified in a particular knowledge representation formalism; the aim of compilation is to allow for efficient, on-line query processing. A theory of compilability has been established for organizing knowledge representation formalisms according to a scheme of "compilability classes", and bears strong analogies to the classical theory of complexity, which permits the organization of computational problems according to complexity classes. We develop a novel theory of compilability, called parameterized compilability, which incorporates the notion of parameterization as used in parameterized complexity and permits for refined analysis of compilability.
10838244
Streaming SMIL Presentations via a Multimedia Semantic Model
The Synchronized Multimedia Integration Language (SMIL) allows Web designers to design complicated and vivid multimedia presentations in a declarative manner. In this paper, an abstract semantic model called Multimedia Augmented Transition Network (MATN) is used to model the conceptual structure of SMIL, as well as the temporal relations and synchronization control. The advantages of using the MATN model are its simplicity and ease of modification (scalability). Users can easily generate their favorite multimedia presentations using MATNs and render them using the SMIL players. Since the SMIL specification is quite new to the Internet society, the functionality of the players is limited, i.e., they often acquire proprietary platforms or cannot deal with MPEG or RTP media objects. Another contribution of this paper is to propose a novel architecture based on Java JMF technology for tackling with such constraints.
1375108
Centaurus: a framework for intelligent services in a mobile environment
In an age where wirelessly networked appliances and devices are becoming commonplace, there is a necessity for connecting them to work together for a mobile user. The design outlined in the paper provides an infrastructure and communication protocol for providing 'smart' services to these mobile devices. This flexible framework allows any medium to be used for communication between the system and the portable device, including infra-red, and BlueTooth. Using Extensible Markup Language (XML) for information passing, gives the system a uniform and easily adaptable interface. We explain our trade-offs in implementation and through experiments we show that the design is feasible and that it indeed provides a flexible structure for providing services. Centaurus provides a uniform infrastructure for heterogeneous services, both hardware and software services, to be made available to the users everywhere where they are needed.