61942372
Simulation-based bug trace minimization with BMC-based refinement
Finding the cause of a bug can be one of the most time-consuming activities in design verification. This is particularly true in the case of bugs discovered in the context of a random simulation- based methodology, where bug traces, or counter-examples, may contain several hundred thousand cycles. In this work we propose Butramin, a bug trace minimizer. Butramin considers a bug trace produced by a random simulator or a semi-formal verification software and produces an equivalent trace of shorter length. Butramin applies a range of minimization techniques, deploying both simulation-based and formal methods, with the objective of producing highly reduced traces that still expose the original bug. We evaluated Butramin on a range of designs, including the publicly available picoJava microprocessor. Our experiments show that in most cases Butramin is able to reduce traces to a small fraction of their initial size, in terms of cycle length and signals involved.
14390424
A Temporal Assertion Extension to Verilog
Many circuit designs need to follow some temporal rules. However, it is hard to express and verify them in the past. Therefore, a temporal assertion extension to Verilog, called Temporal Wizard, is proposed in this paper. It provides several Verilog system tasks for the users to write assertions in testbench directly. Two new concepts, tag and thread, are also introduced so that data can be associated with temporal assertions and provide more functionalities than previous temporal assertion checkers.
17374517
Model Checking with Induction
We have proposed inductive model checking (IMC) to alleviate the state explosion problem in model checking. IMC divides the whole verification tasks into several sub-tasks, and applies the three inductive steps (basis, hypothesis, and induction) to verify a system with model checking. In this paper, we continue our research by determining those temporal formulas, namely, persistent temporal formulas, which are verifiable with IMC. One important characteristic of a persistent temporal formula is that it contains a periodic temporal formula that must be held persistently. From the verification results of the periodic formula with different sequences of states, IMC concludes the verification of the persistent temporal formula
7503916
Context-Aware Wrapping: Synchronized Data Extraction
The deep Web presents a pressing need for integrating large numbers of dynamically evolving data sources. To be more automatic yet accurate in building an integration system, we observe two problems: First, across sequential tasks in integration, how can a wrapper (as an extraction task) consider the peer sources to facilitate the subsequent matching task? Second, across parallel sources, how can a wrapper leverage the peer wrappers or domain rules to enhance extraction accuracy? These issues, while seemingly unrelated, both boil down to the lack of "context awareness": Current automatic wrapper induction approaches generate a wrapper for one source at a time, in isolation, and thus inherently lack the awareness of the peer sources or domain knowledge in the context of integration. We propose the concept of context-aware wrappers that are amenable to matching and that can leverage peer wrappers or prior domain knowledge. Such context awareness inspires a synchronization framework to construct wrappers consistently and collaboratively across their mutual context. We draw the insight from turbo codes and develop the turbo syncer to interconnect extraction with matching, which together achieve context awareness in wrapping. Our experiments show that the turbo syncer can, on the one hand, enhance extraction consistency and thus increase matching accuracy (from 17--83% to 78--94% in F-measure) and, on the other hand, incorporate peer wrappers and domain knowledge seamlessly to reduce extraction errors (from 09--60% to 01--11%).
6929531
PowerBookmarks: a system for personalizable Web information organization, sharing, and management
Users of the Web are overloaded with information. This medium is “polluted” with redundant, erroneous and low quality information. A WWW survey of 11,700 users conducted from April 10 to May 10, 1996[1] indicates that 30.31% of the users report “finding known info” is their problem and 27.80% of the users report organizing collected information as their problem. An empirical study[2] on users’ revisitation patterns to WWW pages found that 58% of an individual’s pages are revisits. With these study results, we believe the Web users would like to build and organize a larger collection of bookmarks for future references than they can reasonably maintain now.
15025719
Entity Search Engine: Towards Agile Best-Effort Information Integration over the Web
2091518
Evaluating the cost of Boolean query mapping
Non-uniform query languages make searching over heterogeneous information sources difcult. Our approach is to allow a user to compose Boolean queries in one rich front-end language. For each user query and target source, we transform the user query into a subsuming query that can be supported by the source but that may return extra documents. The results are then processed by a lter query to yield the correct nal results. This post-ltering approach may involve signicant cost because the documents that the users will not see may have to be retrieved and ltered. There are generally two ways to implement post-ltering: batch post-ltering and incremental post-ltering. In this paper we evaluate the costs of both methods for different search features such as proximity operators. The experimental results show that in many cases incremental post-ltering cost may be acceptable, while the batch post-ltering cost may sometimes be extremely large.