9743987
Complex Visual Activity Recognition Using a Temporally Ordered Database
We propose using a temporally ordered database for complex visual activity recognition. We use a temporal precedence relation together with the assumption of fixed bounded temporal uncertainty of occurrence time of an atomic activity and comparatively large temporal extent of the complex activity. Under these conditions we identify the temporal structure of complex activities as a semiorder and design a database that has semiorder as its data model. A query algebra is then defined for this data model.
19099120
An Extended Object-Oriented Data Model for Large Image Bases
This paper presents an object-oriented data model for an image database. The formal presentation of the model stems from an analysis of the domain of remotely sensed radar images of the Arctic ice. The data model maintains the distinction between generic spatial attributes and representation dependent spatial attributes. This results in a four-layer network of objects, attributes, relations, events and representations. In the representation level, the data model is very close to a functional data model. The model serves as the formal foundation of the VIMSYS (Visual Information Management SYStem) project, which aims to perform content and similarity based query processing of large image repositories.
17115672
Emergent Semantics through Interaction in Image Databases
In this paper, we briefly discuss some aspects of image semantics and the role that it plays for the design of image databases. We argue that images don't have an intrinsic meaning, but that they are endowed with a meaning by placing them in the context of other images and by the user interaction. From this observation, we conclude that, in an image, database users should be allowed to manipulate not only the individual images, but also the relation between them. We present an interface model based on the manipulation of configurations of images.
11105634
Model-based mediation with domain maps
Proposes an extension to current view-based mediator systems called "model-based mediation", in which views are defined and executed at the level of conceptual models (CMs) rather than at the structural level. Structural integration and lifting of data to the conceptual level is "pushed down" from the mediator to wrappers which, in our system, export the classes, associations, constraints and query capabilities of a source. Another novel feature of our architecture is the use of domain maps - semantic nets of concepts and relationships that are used to mediate across sources from multiple worlds (i.e. whose data are related in indirect and often complex ways). As part of registering a source's CM with the mediator, the wrapper creates a "semantic index" of its data into the domain map. We show that these indexes not only semantically correlate the multiple-worlds data, and thereby support the definition of the integrated CM, but they are also useful during query processing, for example, to select relevant sources. A first prototype of the system has been implemented for a complex neuroscience mediation problem.
8323337
Modeling Functional Data Sources as Relations
In this paper we present a model of functional access to data that, we argue, is suitable for modeling a class of data repositories characterized by functional access, such as web sites. We discuss the problem of modeling such data sources as a set of relations, of determining whether a given query expressed on these relations can be translated into a combination of functions defined by the data sources, and of finding an optimal plan to do so.
18656965
Integrating GIS and Imagery Through XML-Based Information Mediation
In this paper, we investigate a mediation-based approach to integrating information from geospatial information sources such as GIS's and databases of geo-referenced imagery. This approach is based on the use of XML to represent the information at the sources, by exporting XML Document Type Definitions (DTD's) associated with each source, and employing XML-based query languages to query integrated views of information at the mediator. Our goal is to enable users to issue a single query to the mediator, and provide the capability to return a result that seamlessly combines information from multiple sources. This paper describes issues in designing such a mediated system for geospatial data. Our notion of mediation for geospatial data is the "logical integration" of data achieved by creating correspondences between related spatial information, similar to the way mediation is done in "standard" databases. Thus, this notion of mediation does not depend on the development of spatial algorithms that operate on images or vector data and achieve "physical integration" through techniques such as image conflation. However, the mediator architecture does allow for the integration of physical integration techniques. The paper discusses issues related to wrapping of GIS and other geospatial sources and issues in querying such sources using an XML-based query language.
14365594
Symbolic Model Checking of Concurrent Programs Using Partial Orders and On-the-Fly Transactions
The state explosion problem is one of the core bottlenecks in the model checking of concurrent software. We show how to ameliorate the problem by combining the ability of partial order techniques to reduce the state space of the concurrent program with the power of symbolic model checking to explore large state spaces. Our new verification methodology involves translating the given concurrent program into a circuit-based model which gives us the flexibility to then employ any model checking technique of choice - either SAT or BDD-based - for verifying a broad range of linear time properties, not just safety. The reduction in the explored state-space is obtained by statically augmenting the symbolic encoding of the program by additional constraints. These constraints restrict the scheduler to choose from a minimal conditional stubborn set of transitions at each state. Another key contribution of the paper, is a new method for detecting transactions on-the-fly which takes into account patterns of lock acquisition and yields better reductions than existing methods which rely on a lockset based analysis. Moreover unlike existing techniques, identifying on-the-fly transactions does not require the program to follow a lock discipline in accessing shared variables. We have applied our techniques to the Daisy test bench and shown the existence of several bugs.
600527
Learning from BDDs in SAT-based bounded model checking
Bounded Model Checking (BMC) based on Boolean Satisfiability (SAT) procedures has recently gained popularity as an alternative to BDD-based model checking techniques for finding bugs in large designs. In this paper, we explore the use of learning from BDDs, where learned clauses generated by BDD-based analysis are added to the SAT solver, to supplement its other learning mechanisms. We propose several heuristics for guiding this process, aimed at increasing the usefulness of the learned clauses, while reducing the overheads. We demonstrate the effectiveness of our approach on several industrial designs, where BMC performance is improved and the design can be searched up to a greater depth by use of BDD-based learning.
195611449
Scheduling tasks in multiprocessor systems using evolutionary strategies
Scheduling tasks in multiprocessor systems is a difficult problem. The paper describes a method based upon evolutionary strategies (using genetic algorithms) to aid in finding good task assignments. The technique is illustrated by scheduling a digital signal processing algorithm on a two processor distributed system.<<ETX>>
878886
Verification of embedded memory systems using efficient memory modeling
We describe verification techniques for embedded memory systems using efficient memory modeling (EMM), without explicitly modeling each memory bit. We extend our previously proposed approach of EMM in bounded model checking (BMC) for a single read/write port single memory system, to more commonly occurring systems with multiple memories, having multiple read and write ports. More importantly, we augment such EMM to providing correctness proofs, in addition to finding real bugs as before. The novelties of our verification approach are in (a) combining EMM with a proof-based abstraction that preserves the correctness of a property up to a certain analysis depth of SAT-based BMC, and (b) modeling arbitrary initial memory state precisely and thereby providing inductive proofs using SAT-based BMC for embedded memory systems. Similar to the previous approach, we construct a verification model by eliminating memory arrays, but retaining the memory interface signals with their control logic and adding constraints on those signals at every analysis depth to preserve the data forwarding semantics. The size of these EMM constraints depends quadratically on the number of memory accesses and the number of read and write ports; and linearly on the address and data widths and the number of memories. We show the effectiveness of our approach on several industry designs and software programs.
38673330
Exploiting Retiming in a Guided Simulation Based Validation Methodology
There has been much interest recently in combining the strengths of formal verification techniques and simulation for functional validation of large designs [6].Typically, a formal test model is first obtained from the design. Then, test sequences which satisfy certain coverage criteria are generated from the test model, which are simulated on the design for functional validation. In this paper, we focus on automatic abstractions for obtaining the test model from the design for simulation vector generation under the transition tour coverage model. Since most efforts using guided simulation have concentrated only on state/transition coverage, without relating these to error coverage of the original design, there is hardly any notion of preserving correctness, which has made it hard to use abstraction effectively.