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Full-Text Articles in Engineering
Bargaining With Deadlines, Tuomas Sandholm, Nir Vulkan
Bargaining With Deadlines, Tuomas Sandholm, Nir Vulkan
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This paper analyzes automated distributive negotiation where agents have firm deadlines that are private information. The agents are allowed to make and accept offers in any order in continuous time. We show that the only sequential equilibrum outcome is the one where the agents wait until the first deadline, at which point that agent concedes everything to the other. This holds for pure and mixed strategies. So, interestingly, rational agents can never agree to a nontrivial split because offers signal enough weakness of bargaining power (early deadline) so that the recipient should never accept. Similarly, the offerer knows that it …
Terabit Burst Switching Progress Report (12/98-6-99), Jonathan S. Turner
Terabit Burst Switching Progress Report (12/98-6-99), Jonathan S. Turner
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This report summarizes progress on Washington University's Terabit Burst Switching Project, supported by DARPA and Rome Air Force Laboratory. This project seeks to demonstrate the feasibility of Burst Switching, a new data communication service which can more effectively exploit the large bandwidths becoming available in WDM transmission systems, than conventional communication technologies like ATM and IP-based packet switching. Burst switching systems dynamically assign data bursts to channels in optical data links, using routing information carried in parallel control channels. The project will lead to the construction of a demonstration switch with throughput exceeding 200 Gb/s and scalable to over 10 …
Constructing Speculative Demand Functions In Equilibrium Markets, Tuomas Sandholm, Fredrik Ygge
Constructing Speculative Demand Functions In Equilibrium Markets, Tuomas Sandholm, Fredrik Ygge
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In computational markets utilizing algorithms that establish a general equilibrium, competitive behavior is usually assumed: each agent makes its demand (supply) decisions so as to maximize its utility (profit) assuming that it has no impact on market prices. However, there is a potential gain from strategic behavior via speculating about others because an agent does affect the market prices, which affect the supply/demand decisions of others, which again affect the market prices that the agent faces. Determining the optimal strategy when the speculator has perfect knowledge about the other agents is a well known problem which has been studied in …
An Algorithm For Optimal Winner Determination In Combinatorial Auctions, Tuomas Sandholm
An Algorithm For Optimal Winner Determination In Combinatorial Auctions, Tuomas Sandholm
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Combinatorial auctions, i.e. auctions where bidders can bid on combinations of items, tend to lead to more efficient allocations than traditional auctions in multi-item auctions where the agents' valuations of the items are not additive. However, determining the winners so as to maximize revenue is NP-complete. First, existing approaches for tackling this problem are reviewed: exhaustive enumeration, dynamic programming, approximation algorithms, and restricting the alloable combinations. Then we present our search algorithm for optimal winner determination. Experiments are shown on several bid distributions. The algorithm allows combinatorial auctions to scale up to significantly larger numbers of items and bids than …
Revenue Equivalence Of Leveled Commitment Contracts, Tuomas Sandholm, Yunhong Zhou
Revenue Equivalence Of Leveled Commitment Contracts, Tuomas Sandholm, Yunhong Zhou
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In automated negotiation systems consisting of self-interested agents, contracts have traditionally been binding. Leveled commitment contracts - i.e. contracts where each party can decommit by paying a predetermined penalty - were recently shown to improve expected social welfare even if agents decommit insincerely in Nash equilibrium. Such contracts differ based on whether agents have to declare their decommitting decisions sequentially or simultaneously, and whether or not agents have to pay the penalties if both decommit. For a given contract, these protocols lead to different decommitting thresholds and probabilities. However, this paper shows that, surprisingly, each protocol leads to the same …
A Proposal For A High-Performance Active Hardware Architecture, Tilman Wolf
A Proposal For A High-Performance Active Hardware Architecture, Tilman Wolf
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Current research in Active Networking is focused on developing software architectures and defining funtionality of Execution Environments. While active network systems show superior functionality compared to traditional networks, they only operate at substantially lower link speeds. To increase the acceptance of Active Network in environments where link speeds of several Gb/s are common, we propose a hardware architecture that performs high-speed packet handling while providing the same flexibility as a common software system. The design exploits the independence between data streams for parallel processing. To measure the impact of different design decisions on the performance of the system, we also …
Assembly And Analysis Of Extended Human Genomic Contig Regions, Eric C. Rouchka, David J. States
Assembly And Analysis Of Extended Human Genomic Contig Regions, Eric C. Rouchka, David J. States
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The Human Genome Project (HGP) has led to the deposit of human genomic sequence in the form of sequenced clones into various databases such as the DNA Data Bank of Japan (DDBJ) (Tateno and Gojobori, 1997), the European Molecular Biology Laboratory (EMBL) Nucleotide Sequence Database (Stoesser, et. al., 1999), and GenBank (Benson, et. al., 1998). Many of these sequenced clones occur in regions where sequencing has taken place either within the same sequencing center or other centers throughout the world. The assembly of extended segments of genomic sequence by looking at overlapping end segments is desired and is currently availabel …
The Design And Performance Of A Pluggable Protocols Framework For Object Request Broker Middleware, Fred Kuhns, Carlos O'Ryan, Douglas C. Schmidt, Jeff Parsons
The Design And Performance Of A Pluggable Protocols Framework For Object Request Broker Middleware, Fred Kuhns, Carlos O'Ryan, Douglas C. Schmidt, Jeff Parsons
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To be an effective platform for performance-sensitive real-time and embedded applications, off-the-shelf OO middleware like CORBA, DCOM, and Java RMI must preserve communication-layer quality of service (QoS) properties to applications end-to-end. However, conventional OO middleware interoperability protocols, such as CORBA's GIOP/IIOP or DCOM's MS-RPC, are not well suited for applications that cannot tolerate the message footprint size, latency, and jitter associated with general-purpose messaging and transport protocols. It is essential, therefore, to develop standard plugable protocols frameworks that allow custom messaging and transport protocols to be configured flexibly and used transparently by applications. This paper provides three contributions to research …
Anmac: A Novel Architectural Framework For Network Management And Control Using Active Networks, Samphel Norden
Anmac: A Novel Architectural Framework For Network Management And Control Using Active Networks, Samphel Norden
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In this paper, we propose a new framework called Active Network Management and Control (ANMAC) for the management and control of high speed networks. The software architecture in ANMAC allows routers to execute dynamically loadable kernel plug-in modules which perform diagnostic functions for network management. ANMAC uses mobile probe packets to perform efficient resource reservation (using our novel reservation scheme), facilitate feedback-based congestion control, and to provide "distributed debugging" of complex anomalous network behavior. ANMAC also provides security measures against IP spoofing, and other security attacks. The network manager has the flexibility to install custom scripts in routers for tracking …
Emediator: A Next Generation Electronic Commerce Server, Tuomas Sandholm
Emediator: A Next Generation Electronic Commerce Server, Tuomas Sandholm
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This paper presents eMediator, a next generation electronic commerce server that demonstrates some ways in which AI, algorithmic support, and game theoretic incentive engineering can jointly improve the efficiency of ecommerce. First, its configurable auction house includes a variety of generalized combinatorial auctions, price setting mechanism, novel bid types, mobile agents, and user support for choosing an auction type. Second, its leveled commitment contract optimizer determines the optimal contract price and decommitting penalties for a variety of leveled commitment contracting protocols, taking into account that rational agents will decommit insincerely in taking into account that rational agents will decommit insincerely …
Algorithms For Optimizing Leveled Commitment Contracts, Thomas Sandholm, Sandeep Sikka, Samphel Norden
Algorithms For Optimizing Leveled Commitment Contracts, Thomas Sandholm, Sandeep Sikka, Samphel Norden
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In automated negotiation systems consisting of self-interested agents, contracts have traditionally been binding. Leveled commitment contracts - i.e. contracts where each party can decommit by paying a predetermined penalty - were recently shown to improve Pareto efficiency even if agents rationally decommit in Nash equilibrium using inflated thresholds on how good their outside offers must be before they decommit. This paper operationalizes the four leveled commitment contracting protocols by presenting algorithms for using them. Algorithms are presented for computing the Nash equilibrium decomitting thresholds and decommitting probabilities given the contract price and the penalties. Existence and uniqueness of the equilibrium …
Optimal Flow Aggregation, Subhash Suri, Tuomas Sandholm, Priyank Warkhede
Optimal Flow Aggregation, Subhash Suri, Tuomas Sandholm, Priyank Warkhede
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Current IP routers are stateless: they forward individual packets based on the destination address contained in the packet header, but maintain no information about the application or flow to which a packet belongs. This stateless service model works well for best effort datagram delivery, but is grossly inadequate for applications that require quality of service guarantees, such as audio, video, or IP telephony. Maintaining state for each flow is expensive because the number of concurrent flows at a router can be in the hundreds of thousands. Thus, stateful solutions such as Intserv (integrated services) have not been adopted for their …
Multiway Range Trees: Scalable Ip Lookup With Fast Updates, Subhash Suri, George Varghese, Piryank Ramesh Warkhede
Multiway Range Trees: Scalable Ip Lookup With Fast Updates, Subhash Suri, George Varghese, Piryank Ramesh Warkhede
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Internet routers forward packets based on the destination address of a packet. A packet's address is matched against the destination prefixes stored in the router's forwarding table, and the packet is sent to the output interface determined by the longest matching prefix. While some existing schemes work well for IPv4 addresses, we believe that none of the current schemes scales well to IPv6, especially when fast updates are required. As the Internet evolves into a global communication medium, requiring multiple addresses per user, the switch to longer addresses (e.g. IPv6) seems inevitable despite temporary measures such as network addres translation …
Pattern Matching Techniques And Their Applications To Computational Molecular Biology - A Review, Eric C. Rouchka
Pattern Matching Techniques And Their Applications To Computational Molecular Biology - A Review, Eric C. Rouchka
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Pattern matching techniques have been useful in solving many problems associated with computer science, including data compression (Chrochemore and Lecroq, 1996), data encryption (RSA Laboratories, 1993), and computer vision (Grimson and Huttenlocher, 1990). In recent years, developments in molecular biology have led to large scale sequencing of genomic DNA. Since this data is being produced in such rapid fasion, tools to analyze DNA segments are desired. The goal here is to discuss various techniques and tools for solving various pattern matching questions in computational biology, including optimal sequence alignment, multiple sequence alignment, and buidling models to describe sequence families using …
Design Issues For High Performance Active Routers, Tilman Wolf, Jonathan Turner
Design Issues For High Performance Active Routers, Tilman Wolf, Jonathan Turner
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Active networking is a general approach to incorporating general-purpose computational capabilities within the communications infrastructure of data networks. This paper proposes a design of a scalable, high performance active router. This is used as a vehicle for studying the key design issues that must be resolved to allow active networking to become a mainstream technology.
Commbench - A Telecommunications Benchmark For Network Processors, Tilman Wolf, Mark Franklin
Commbench - A Telecommunications Benchmark For Network Processors, Tilman Wolf, Mark Franklin
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This paper presents a benchmark, CommBench, for use in evaluating and designing telecommunications network processors. The benchmark applications focus on small, computationally intense program kernels typical of the network processor environment. The benchmark is composed of eight programs, four of them oriented towards packet header processing and four oriented towards data stream procesing. The benchmark is defined and various characteristics of the benchmark are presented. These include instruction frequencies, computational complexity, and cache performance. These measured characteristics are compared to the SPEC benchmark which has traditionally been used in evaluating workstation processors. Three examples are presented indicating how CommBench can …
Tracking Mobile Units For Dependable Message Delivery, Amy L. Murphy, Gruia-Catalin Roman, George Varghese
Tracking Mobile Units For Dependable Message Delivery, Amy L. Murphy, Gruia-Catalin Roman, George Varghese
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As computing components get smaller and people become accustomed to having computational power at their disposal at any time, mobile computing is developing as an important research area. One of the fundamental problems in mobility is maintaining connectivity through message passing as the user moves through the network. An approach to this is to have a single home node constantly track the current location of the mobile unit and forward messages to this location. One problem with this approach is that during the update to the home agent after movement, messages are often dropped, especially in the case of frequent …
Auctions Without Common Knowledge, Sviatoslav B. Brainov, Tuomas W. Sandholm
Auctions Without Common Knowledge, Sviatoslav B. Brainov, Tuomas W. Sandholm
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This paper proves that the revenue equivalence theorem ceases to hold for auctions without common knowledge about the agents' prior beliefs. That is, different auction forms yield different expected revenue. To prove this, an auction game is converted to a Bayesian decision problem with an infinite hierarchy of beliefs. A general solution for such Bayesian decision problems is proposed. The solution is a generalization of the standard Bayesian solution and coincides with it for finite belief trees and for trees representing common knowledge. It is shown how the solution generalizes the frequently used technique of backward induction for infinite belief …
A Fine-Grained Model For Code Mobility, Cecilia Mascolo, Gian Pietro Picco, Gruia-Catalin Roman
A Fine-Grained Model For Code Mobility, Cecilia Mascolo, Gian Pietro Picco, Gruia-Catalin Roman
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In this paper, we take the extreme view that every line of code is potentially mobile, i.e., may be duplicated and/or moved from one program context to another on the same host or across the network. Our motivation is to gain a better understanding of the range of constructs and issues facing the designer of a mobile code system, in a setting that is abstract and unconstrained by compilation and performance considerations traditionally associated with programming language design. Incidental to our study is an evaluatoin of the expressive power of Mobile UNITY, a notation and proof logic for mobile computing.
Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco
Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco
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The provision of a reliable communication infrastructure for mobile agents is still an open research issue. The challenge to reliability we address in this work does not come from the possibility of faults, but rather from the mere presence of mobility, which slightly complicates the problem of ensuring the delivery of information even in a fault-free network. For instance, the asynchronous nature of message passing and agent migration may cause situations where messages forever chase a mobile agent that moves frequently from one host to another. Current solutions rely on conventional technologies that either do not provide a solution for …
Floor Control Protocol For Alx Video Conference Application, Ruibiao Qiu
Floor Control Protocol For Alx Video Conference Application, Ruibiao Qiu
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With wide deployment of high-speed networks such as vBNS today, video-conference applications over WANs have become increasingly feasible. MMX has proven to be a good desktop video-conference devide for local ATM networks. Now, ALX has been designed to extend MMX's video conferencing capability to IP-over-ATM WANs such as vBNS. In this report, we discuss a floor control protocol for ALX video-conference applications. We first show how an "ideal" protocol should behave to meet our requirements. Then we compare three protocols based on distributed algorithms, and a protocol based on a centralized algorithm. Based on the comparison and performance analysis, we …
Software Engineering For Mobility: A Roadmap, Gruia-Catalin Roman, Gian Pietro Picco, Amy L. Murphy
Software Engineering For Mobility: A Roadmap, Gruia-Catalin Roman, Gian Pietro Picco, Amy L. Murphy
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The term distributed computing conjures the image of a fixed network structure whose nodes support the execution of processes that communicate with each other via messages traveling along links. Peer-to-peer communication is feasible but client-server relationships dominate. More recently, servers have been augmented with brokerage capabilities to facilitate discovery of available services. Stability is the ideal mode of operation; changes are relatively slow; even in the case of failure, nodes and links are expected eventually to come back up. By contrast, mobility represents a total meltdown of all the stability assumptions (explicit or implicit) associated with distributed computing. The network …
A Rapid Development Of Dependable Applications In Ad Hoc Mobility, Amy L. Murphy
A Rapid Development Of Dependable Applications In Ad Hoc Mobility, Amy L. Murphy
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Advances in wireless communication and network computing technologies make possible new kinds of applications involving transient interactions among physical components that move across a wide range of spaces, from the confines of a room to the airspace across an ocean, and require no fixed networking infrastructure to communicate with one another. Such components may come together to form ad hoc networks for the purpose of exchanging information or in order to engage in cooperative task-oriented behaviors. Ad hoc networks are assembled, reshaped and taken apart as components move in and out of communication range; all interactions are transient; computations become …