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The study of the web as a graph is not only fascinating in its own right, but also yields valuable insight into web algorithms for crawling, searching and community discovery, and the sociological phenomena which characterize its evolution. We report on experiments on local and global properties of the web graph using two Altavista crawls each with over 200(More)
Java is typically compiled into an intermediate language, JVML, that is interpreted by the Java Virtual Machine. Because mobile JVML code is not always trusted, a bytecode verifier enforces static constraints that prevent various dynamic errors. Given the importance of the bytecode verifier for security, its current descriptions are inadequate. This paper(More)
The Connectivity Server is a special-purpose database whose schema models the Web as a graph graph where URLs are nodes and hyperlinks are directed edges. The Link Database provides fast access to the hyperlinks. To support a wide range of graph algorithms, we find it important to fit the Link Database into memory. In the first version of the Link Database,(More)
This paper defines a simple guarded-command–like language and its semantics. The language is used as an intermediate language in generating verification conditions for Java. The paper discusses why it is a good idea to generate verification conditions via an intermediate language, rather than directly. Publication history. This paper appears in Formal(More)
Research on buying behavior indicates that buying guides perform an important role in the overall buying process. However, while many buying guides can be found on the Web, finding those guides is difficult to impossible for the average consumer. Web search engines typically index many buying guides on many topics, but simple queries do not often return(More)
When writing computer programs, programmers make assumptions about the relations among variables. In object-oriented programs, these assumptions include relations among the instance variables of a single object, relations often referred to as object invariants. It is a good idea to explicitly annotate a program with these assumptions. Then, a static(More)
Yahoo! is building a set of scalable, highly-available data storage and processing services, and deploying them in a cloud model to make application development and ongoing maintenance significantly easier. In this paper we discuss the vision and requirements, as well as the components that will go into the cloud. We highlight the challenges and research(More)
We introduce and formalize a novel constrained path optimization problem that is the heart of the real-time ad serving task in the Yahoo! (formerly RightMedia) Display Advertising Exchange. In the Exchange, the ad server's task for each display opportunity is to compute, with low latency, an optimal valid path through a directed graph representing the(More)