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Abstract. To produce a program guaranteed to satisfy a given specification one can synthesize it from a formal constructive proof that a computation satisfying that specification exists. This process is particularly effective if the specifications are written in a high-level language that makes it easy for designers to specify their goals. We consider a high-level specification language that results from adding knowledge to a fragment of Nuprl specifically tailored for specifying distributed protocols, called event theory. We then show how high-level knowledge-based programs can be synthesized from the knowledge-based specifications using a proof development system such as Nuprl. Methods of Halpern and Zuck [20] then apply to convert these knowledge-based protocols to ordinary protocols. These methods can be expressed as heuristic transformation tactics in Nuprl.

Oracle RDBMS has supported XML data management for more than six years since version 9i. Prior to 11g, textcentric XML documents can be stored as-is in a CLOB column and schema-based data-centric documents can be shredded and stored in object-relational (OR) tables mapped from their XML Schema. However, both storage formats have intrinsic limitations-XML/CLOB has unacceptable query and update performance, and XML/OR requires XML schema. To tackle this problem, Oracle 11g introduces a native Binary XML storage format and a complete stack of data management operations. Binary XML was designed to address a wide range of real application problems encountered in XML data management-schema flexibility, amenability to XML indexes, update performance, schema evolution, just to name a few.In this paper, we introduce the Binary XML storage format based on Oracle SecureFiles System [21]. We propose a lightweight navigational index on top of the storage and an NFA-based navigational algorithm to provide efficient streaming processing. We further optimize query processing by exploiting XML structural and schema information that are collected in database dictionary. We conducted extensive experiments to demonstrate high performance of the native Binary XML in query processing, update, and space consumption.

We propose a principled approach to model secrecy in multiagent systems, by defining a set of possible observations and providing agents with algorithms used to distinguish the possible states of the system. Our approach fits naturally within a knowledgebased account of secrecy. By adjusting both the kind of observations and the capabilities of the agents, we can capture in a natural way different forms of secrecy in the presence of perfect cryptography. In particular, we show how to model extraction secrecy. Our formalization suggests a unified definition of secrecy for cryptographic protocols and for systems that seek to prevent inadmissible flows of information.

Consider a distributed system N in which each agent has an input value and each communication link has a weight. Given a global function, that is, a function f whose value depends on the whole network, the goal is for every agent to eventually compute the value f (N ). We call this problem global function computation. Various solutions for instances of this problem, such as Boolean function computation, leader election, (minimum) spanning tree construction, and network determination, have been proposed, each under particular assumptions about what processors know about the system and how this knowledge can be acquired. We give a necessary and sufficient condition for the problem to be solvable that generalizes a number of well-known results (Attyia et al. in J ACM 35(4):845-875, 1988; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 7(1):69-89, 1996; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 10(9):878-887, 1999). We then provide a knowledge-based (kb) program (like those of Fagin et al. (Reasoning about knowledge, MIT Press,