Distributed Algorithmic Mechanism Design (DAMD) combines theoretical computer science's traditional focus on computational tractability with its more recent interest in incentive compatibility and distributed computing. The Internet's decentralized nature, in which distributed computation and autonomous agents prevail, makes DAMD a very natural approach for many Internet problems. This paper first outlines the basics of DAMD and then reviews previous DAMD results on multicast cost sharing and interdomain routing. The remainder of the paper describes several promising research directions and poses some specific open problems.

The routing of traffic between... this paper, we address the problem of interdomain routing from a mechanism-design point of view. The application of mechanism-design principles to the study of routing is the subject of earlier work by Nisan and Ronen [15] and Hershberger and Suri [11]. In this paper, we formulate and solve a version of the routing-mechanism design problem that is different from the previously studied version in three ways that make it more accurately reflective of real-world interdomain routing: (1) we treat the nodes as strategic agents, rather than the links; (2) our mechanism computes lowest-cost routes for all source-destination pairs and payments for transit nodes on all of the routes (rather than computing routes and payments for only one source-destination pair at a time, as is done in [15,11]); (3) we show how to compute our mechanism with a distributed algorithm that is a straightforward extension to BGP and causes only modest increases in routingtable size and convergence time (in contrast with the centralized algorithms used in [15,11]). This approach of using an existing protocol as a substrate for distributed computation may prove useful in future development of Internet algorithms generally, not only for routing or pricing problems. Our design and analysis of a strategyproof, BGP-based routing mechanism provides a new, promising direction in distributed algorithmic mechanism design, which has heretofore been focused mainly on multicast cost sharing.

The coverage and recency of the major World Wide Web search engines was analyzed, yielding some surprising results. The coverage of any one engine is significantly limited: No single engine indexes more than about one-third of the "indexable Web," the coverage of the six engines investigated varies by an order of magnitude, and combining the results of the six engines yields about 3.5 times as many documents on average as compared with the results from only one engine. Analysis of the overlap between pairs of engines gives an estimated lower bound on the size of the indexable Web of 320 million pages.

Software systems have been using “just-in-time ” compilation (JIT) techniques since the 1960s. Broadly, JIT compilation includes any translation performed dynamically, after a program has started execution. We examine the motivation behind JIT compilation and constraints imposed on JIT compilation systems, and present a classification scheme for

in Proceedings of the 3rd ACM Conference on Electronic Commerce, Tampa FL, October 2001. This work was supported by the DoD University Research Initiative (URI) program administered by the Oce of Naval Research under Grant N00014-01-1-0795.

The first part of this paper provides rigorous definitions for several basic concepts underlying the design of dependable programs, such as specification, program semantics, exception, program correctness, robustness, failure, fault, and error. The second part investigates what it means to handle exceptions in modular programs structured as hierarchies of data abstractions. The problems to be solved at each abstraction level, such as exception detection and propagation, consistent state recovery and masking are examined in detail. Both programmed exception handling and default exception handling (such as embodied for example in recovery blocks or database transactions) are considered. An assessment of the adequacy of backward recovery in providing tolerance of software design faults is made. An earlier version of this paper was published in "Dependability of Resilient Computers", T. Anderson, Editor, BSP Professional Books, Blackwell Scientific Publications, UK, 1989, pp. 68-97 INTRO...

We show how to triangulate polygonal regions---adding extra vertices as necessary--- with triangles of guaranteed quality. Using only O(n) triangles, we can guarantee that the smallest height (shortest dimension) of a triangle in a triangulation of an n-vertex polygon (with holes) is a constant fraction of the largest possible. For simple polygons, using O(n log n) triangles, we can guarantee that the largest angle is no greater than 150 ffi . This bound increases to O(n 3=2 ) triangles for the case of polygons with holes. We can add the guarantee on smallest height to these no-large-angle results, without increasing the asymptotic complexity of the triangulation. Finally we give a nonobtuse triangulation algorithm for convex polygons that uses O(n 1:85 ) triangles. Keywords: Computational geometry, mesh generation, triangulation, angle condition. 1. Introduction There have been a number of recent papers on the general problem of triangulating a planar point set or pol...

The routing of traffic between Internet domains, or Autonomous Systems (ASes), a task known as interdomain routing, is currently handled by the Border Gateway Protocol (BGP) [17]. Using BGP, autonomous systems can apply semantically rich routing policies to choose interdomain routes in a distributed fashion. This expressiveness in routing-policy choice supports domains ’ autonomy in network operations and in business decisions, but it comes at a price: The interaction of locally defined routing policies can lead to unexpected global anomalies, including route oscillations or overall protocol divergence (see, e.g., [20]). Networking researchers have addressed this problem by devising constraints on policies that guarantee BGP convergence without unduly limiting expressiveness and autonomy (see, e.g., [7, 8]). In addition to taking this engineering or “protocol-design ” approach, researchers have approached interdomain routing from an economic or “mechanism-design ” point of view. It is known that lowest-cost-path (LCP) routing can be implemented in a truthful, BGP-compatible manner [3] but that several other natural classes of routing policies cannot [2, 5]. In this paper, we present a natural class of interdomain-routing policies that is more realistic than LCP routing and admits incentive-compatible, BGP-compatible implementation. We also present several positive steps toward a general theory of incentive-compatible interdomain routing.

We continue the study of multicast cost sharing from the viewpoints of both computational complexity and economic mechanism design. We provide fundamental lower bounds on the network complexity of group-strategyproof, budget-balanced mechanisms. We also extend a classical impossibility result in game theory to show that no strategyproof mechanism can be both approximately efficient and approximately budget-balanced. Our results show that one important and natural case of multicast cost sharing is an example of a canonical hard problem in distributed, algorithmic mechanism design; in this sense, they represent progress toward the development of a complexity theory of Internet computation.

this paper we study the performance of two other splitting methods, and compare them against the kd-tree splitting method. The first, called slidingmidpoint, is a splitting method that was introduced by Mount and Arya in the ANN library for approximate nearest neighbor searching [30]. This method was introduced into the library in order to better handle highly clustered data sets. We know of no analysis (empirical or theoretical) of this method. This method was designed as a simple technique for addressing one of the most serious flaws in the standard kd-tree splitting method. The flaw is that when the data points are highly clustered in low dimensional subspaces, then the standard kd-tree splitting method may produce highly elongated cells, and these can lead to slow query times. This splitting method starts with a simple midpoint split of the longest side of the cell, but if this split results in either subcell containing no data points, it translates (or "slides") the splitting plane in the direction of the points until hitting the first data point. In Section 3.1 we describe this splitting method and analyze some of its properties. The second splitting method, called minimum-ambiguity, is a query-based technique. The tree is given not only the data points, but also a collection of sample query points, called the training points. The algorithm applies a greedy heuristic to build the tree in an attempt to minimize the expected query time on the training points. We model query processing as the problem of eliminating data points from consideration as the possible candidates for the nearest neighbor. Given a collection of query points, we can model any stage of the nearest neighbor algorithm as a bipartite graph, called the candidate graph, whose vertices correspond t...