15889327
Towards Better Approximation of Winner Determination for Combinatorial Auctions with Large Number of Bids
We propose new approximate algorithms for combinatorial auctions with massively large number of (more than 100,000) bids. In this paper, we focus on a more practical approximated algorithm in the context of revenue maximization. We propose a hill-climbing greedy algorithm, a SA-like random search algorithm, and their enhancement for searching multiple key parameter values. The experimental results demonstrate that our algorithms perform approximately 0.997 optimality compared with the optimal solutions and better than previously presented approximated algorithms. We also demonstrate that our algorithms are a kind of anytime algorithm that bring better results in shorter computational time that can be applied to large and dynamic electronic markets.
39290569
Implementing a proxy agent based writable web for a dynamic information sharing system
In this paper, we propose a Web based information sharing system called the Proxy Agent-based Information Sharing(PAIS).We also developed a writable Web mechanism called Web browser-based Direct Editing (Wedit), that is a major component of PAIS. Wedit enables public users to effectively edit HTML text on an existing Web browser. Since Wedit was developed with conventional technologies, users quickly learn how to use it. PAIS is implemented by using Wedit and a proxy agent. PAIS enables users to share information via Web pages using Wedit. The proxy agent maintainsusers' editing data. The agent autonomously sends its user's modification data to other agents in the same community. In PAIS, certain confidential information in the community is not publicly shared by using the proxy agent.
1779412
Designing an auction protocol under asymmetric information on nature's selection
Internet auctions are becoming an especially popular part of Electronic Commerce and auction protocols have been studied very widely in the field of multi-agent systems and AI. However, correctly judging the quality of auctioned goods is often difficult for non-experts (amateurs), in particular, on the Internet auctions. In this paper, we formalize such a situation so that Nature selects the quality of the auctioned good. Experts can observe Nature's selection (i.e., the quality of the good) correctly, while amateurs including the auctioneer cannot. In other words, the information on Nature's selection is asymmetric between experts and amateurs. In this situation, it is difficult to attain an efficient allocation, since experts have a clear advantage over amateurs and they would not reveal their valuable information without some reward. Thus, in this paper, we develop a new auction protocol in which truth-telling is a dominant strategy for each expert. This can be done by putting these experts in a situation similar to Prisoner's Dilemma. If they cooperate and tell lies, they can exclude amateurs, but betraying is a dominant strategy. By making experts to elicit their information on the quality of the good, the protocol can achieve a socially desirable, i.e., Pareto efficient allocation if certain assumptions are satisfied.
2241033
Multiple negotiations among agents for a distributed meeting scheduler
We present a method for multi-agent negotiation for implementing a distributed meeting scheduler. In the meeting scheduler, an agent negotiates with other agents about making a public schedule by referring user's private schedules and preferences. We propose a new persuasion method for multi-agent negotiation for reflecting private preferences. We call the method multiple negotiations. In order to reach a consensus effectively, we propose an effective preference revision mechanism based on the multi attribute utility theory. We have implemented a distributed meeting scheduler to show how effectively the multiple negotiations can be used. The result shows that the multiple negotiations are effective in supporting group decision-making for scheduling a meeting.
20000085
Toward a Large Scale E-Market: A Greedy and Local Search Based Winner Determination
Combinatorial auction is one of the most popular market mechanisms and it has a huge effect on electronic markets and political strategies. On large scale e-markets, we need a good approximation algorithm for winner determination that is robust for changing the distribution and the number of bids in an auction. We proposed approximate algorithms for combinatorial auctions with massively large number of (more than 100,000) bids. In this paper, we show the robustness of our winner determination algorithms for combinatorial auctions with large number of bids. Experimental results demonstrate that our proposed algorithms are robust on changing the distribution and the number of bids in an auction. Finally, we shortly describe a theoretical limitation about our algorithms that concerns with giving truthfulness of the auction mechanism.
9544952
An Approach to Building Mobile Intelligent Agents Based on Anytime Migration
In this paper, we present an implementation of a Java-based framework for building mobile agents : MiLog (Mobile intelligent agents using Logic programming). MiLog provides logic programming and Java programming for developing intelligent agents since it helps users to effectively construct intelligent mechanisms. We address how to realize an anytime migration mechanism, a HTTP(Hyper Text Transfer Protocol)-based communication mechanism among agents, and web service/access mechanism. Anytime migration enables agents to reactively and autonomously migrate from one computer to another. We present practical applications that have been built on MiLog framework. These applications demonstrate that MiLog is an effective tool for developing practical applications based on mobile intelligent agents.
32325022
Algorithms for Finding Distance-Edge-Colorings of Graphs
For a bounded integer l, we wish to color all edges of a graph G so that any two edges within distance l have different colors. Such a coloring is called a distance-edge-coloring or an l-edge-coloring of G. The distance-edge-coloring problem is to compute the minimum number of colors required for a distance-edge-coloring of a given graph G. A partial k-tree is a graph with tree-width bounded by a fixed constant k. We first present a polynomial-time exact algorithm to solve the problem for partial k-trees, and then give a polynomial-time 2-approximation algorithm for planar graphs.
2226240
Partitioning Trees of Supply and Demand
Assume that a tree T has a number ns of "supply vertices" and all the other vertices are "demand vertices." Each supply vertex is assigned a positive number called a supply, while each demand vertex is assigned a positive number called a demand. One wish to partition T into exactly ns subtrees by deleting edges from T so that each subtree contains exactly one supply vertex whose supply is no less than the sum of demands of all demand vertices in the subtree. The "partition problem" is a decision problem to ask whether T has such a partition. The "maximum partition problem" is an optimization version of the partition problem. In this paper, we give three algorithms for the problems. First is a linear-time algorithm for the partition problem. Second is a pseudo-polynomial-time algorithm for the maximum partition problem. Third is a fully polynomial-time approximation scheme (FPTAS) for the maximum partition problem.
3208882
Partitioning a Weighted Graph to Connected Subgraphs of Almost Uniform Size
Assume that each vertex of a graph G is assigned a nonnegative integer weight and that l and u are nonnegative integers. One wish to partition G into connected components by deleting edges from G so that the total weight of each component is at least l and at most u. Such an “almost uniform” partition is called an $(l, u) \mbox{-}$partition. We deal with three problems to find an $(l, u) \mbox{-}$partition of a given graph. The minimum partition problem is to find an $(l, u) \mbox{-}$partition with the minimum number of components. The maximum partition problem is defined similarly. The p-partition problem is to find an $(l, u) \mbox{-}$partition with a fixed number p of components. All these problems are NP-complete or NP-hard even for series-parallel graphs. In this paper we show that both the minimum partition problem and the maximum partition problem can be solved in time O(u4n) and the p-partition problem can be solved in time O(p2u4n) for any series-parallel graph of n vertices. The algorithms can be easily extended for partial k-trees, that is, graphs with bounded tree-width.
751173
Approximability of Partitioning Graphs with Supply and Demand
Suppose that each vertex of a graph G is either a supply vertex or a demand vertex and is assigned a positive real number, called the supply or the demand. Each demand vertex can receive “power” from at most one supply vertex through edges in G. One thus wishes to partition G into connected components so that each component C either has no supply vertex or has exactly one supply vertex whose supply is at least the sum of demands in C, and wishes to maximize the fulfillment, that is, the sum of demands in all components with supply vertices. This maximization problem is known to be NP-hard even for trees having exactly one supply vertex and strongly NP-hard for general graphs. In this paper, we focus on the approximability of the problem. We first show that the problem is MAXSNP-hard and hence there is no polynomial-time approximation scheme (PTAS) for general graphs unless P=NP. We then present a fully polynomial-time approximation scheme (FPTAS) for series-parallel graphs having exactly one supply vertex. The FPTAS can be easily extended for partial k-trees, that is, graphs with bounded treewidth.
13514702
Partitioning a Multi-weighted Graph to Connected Subgraphs of Almost Uniform Size
Assume that each vertex of a graph G is assigned a constant number q of nonnegative integer weights, and that q pairs of nonnegative integers li and ui, 1 ≤i ≤q, are given. One wishes to partition G into connected components by deleting edges from G so that the total i-th weights of all vertices in each component is at least li and at most ui for each index i, 1 ≤i ≤q. The problem of finding such a “uniform” partition is NP-hard for series-parallel graphs, and is strongly NP-hard for general graphs even for q = 1. In this paper we show that the problem and many variants can be solved in pseudo-polynomial time for series-parallel graphs. Our algorithms for series-parallel graphs can be extended for partial k-trees, that is, graphs with bounded tree-width.