6169415
The Color-Degree Matrix and the Number of Multicolored Trees in Star Decompositions
In a previous paper we investigated the problem of counting the number of multicolored spanning trees in biclique decompositions. In particular for acyclic decompositions we found the minimum and maximum numbers of multicolored trees. We now introduce the color-degree matrix C and show that the number of multicolored trees is bounded below by the determinant of C with a row deleted. In fact, we obtain equality for acyclic decompositions and for star decompositions. Unfortunately, for arbitrary decompositions the ratio of this determinant to the actual number of trees can approach zero. We find that star decompositions on n vertices are in one to one correspondence with tournaments on n ? 1 vertices. This allows us to determine that the minimum number of multicolored trees among all star decompositions of Kn is (n ? 1)! and the average number is ((n + 1)/2)n ? 2. We bound the maximum number of multicolored trees between this average and ?n2/4?(n ? 1)/2 ? ?(n ? 2)2/4?(n ? 1)/2.
33569862
Survey of Double Vertex Graphs
Abstract. Let G be a (V,E) graph of order p≥2. The double vertex graphU2(G) is the graph whose vertex set consists of all 2-subsets of V such that two distinct vertices {x,y} and {u,v} are adjacent if and only if |{x,y}∩{u,v}|=1 and if x=u, then y and v are adjacent in G. For this class of graphs we discuss the regularity, eulerian, hamiltonian, and bipartite properties of these graphs. A generalization of this concept is n-tuple vertex graphs, defined in a manner similar to double vertex graphs. We also review several recent results for n-tuple vertex graphs.
30471911
Hamiltonian Decompositions of Cayley Graphs on Abelian Groups of Odd Order
2599117
Composite Synchronization in Parallel Discrete-Event Simulation
This paper considers a technique for composing global (barrier-style) and local (channel scanning) synchronization protocols within a single parallel discrete-event simulation. Composition is attractive because it allows one to tailor the synchronization mechanism to the model being simulated. We first motivate the problem by showing the large performance gap that can be introduced by a mismatch of model and synchronization method. Our solution calls for each channel between submodels to be classified as synchronous or asynchronous. We mathematically formulate the problem of optimally classifying channels and show that, in principle, the optimal classification can be obtained in time proportional to max{C/spl times/log C, V/spl times/N}, where C is the number of channels, V the number of unique minimal delays on those channels, and N is the number of submodels. We then demonstrate an implementation which finds an optimal solution at runtime and consider its performance on network topologies, including one of the global Internet at the autonomous system level. We find that the automated method effectively determines channel assignments that maximize performance.
37149853
New Challenges in the World Wide Wisdom Web (W4) Research
This talk addresses the research and development needs for creating the new paradigm shift in Internet computing. In particular, it presents a promising answer to such needs, called the World Wide Wisdom Web (W4), and identifies several research challenges and enabling technologies in developing the W4.
30869604
Towards Efficient Data Re-mining (DRM)
The problem that we tackle here is a practical one: When users interactively mine association rules, it is often the case that they have to continuously tune two thresholds: minimum support and minimum confidence, which describe the users' changing requirements. In this paper, we present an efficient data re-mining (DRM) technique for updating previously discovered association rules in light of threshold changes.
3502042
Reactive agents for adaptive image analysis
195860670
Optimal stream replication for video simulcasting
Video simulcasting enables a sender to generate multiple streams for the same video program but at different rates, targeting receivers of different capacities. Each stream can then be distributed to the target receivers via broadcast or multicast channels. One of the critical issues in video simulcasting is to strike a balance between bandwidth consumption and the user satisfaction. This is because stream replication introduces redundancy which can potentially lead to excessive use of the bandwidth, while on the other hand there usually is a mismatch between a receiver's capacity and the limited choice of the stream bandwidths. We present a formal study on the above issue, which we refer as the optimal stream replication problem. We first formulate the optimal replication problem for a given session bandwidth budget and number of streams, with the objective of minimizing the expected mismatch for all the receivers in the session. A proper choice for the number of the replicated streams is critical in the overall bandwidth provisioning. Though it has been largely assumed that the number of streams is predetermined by service providers, we find that dynamic adjustment of stream number is possible in advanced video stream systems, such as the MPEG-4 Delivery Multimedia Integration Framework (DIMF), and systems employing fast video transcoding algorithms. Therefore, we also study the case of a flexible stream number, with the objective of jointly optimize the stream number and bandwidth allocated to each stream.