ppxscal/embedding_network huggingface dataset:
On k-ary spanning trees of tournaments
Authors: Xiaoyun Lu, Da-Wei Wang, Gerard J. Chang, In-Jen Lin, C. K. Wong
Venue: Journal of Graph Theory (1999)

It is well known that every tournament contains a Hamiltonian path, which can be restated as that every tournament contains a unary spanning tree. The purpose of this article is to study the general problem of whether a tournament contains a k-ary spanning tree. In particular, we prove that, for any fixed positive integer k, there exists a minimum number h(k) such that every tournament of order at least h(k) contains a k-ary spanning tree. The existence of a Hamiltonian path for any tournament is the same as h(1) = 1. We then show that h(2) = 4 and h(3) = 8. The values of h(k) remain unknown for k &ge; 4. &copy; 1999 John & Sons, Inc. J Graph Theory 30: 167&ndash;176, 1999 Part of this work was done while visiting the Chinese University of Hong Kong. Research by Dr. Gerard J. Chang supported in part by the National Science Council under grant NSC87-2115-M009-007.
Model-based human shape reconstruction from multiple views
Authors: Jonathan Starck, Adrian Hilton
Venue: Computer Vision and Image Understanding (2008)

Image-based modelling allows the reconstruction of highly realistic digital models from real-world objects. This paper presents a model-based approach to recover animated models of people from multiple view video images. Two contributions are made, a multiple resolution model-based framework is introduced that combines multiple visual cues in reconstruction. Second, a novel mesh parameterisation is presented to preserve the vertex parameterisation in the model for animation. A prior humanoid surface model is first decomposed into multiple levels of detail and represented as a hierarchical deformable model for image fitting. A novel mesh parameterisation is presented that allows propagation of deformation in the model hierarchy and regularisation of surface deformation to preserve vertex parameterisation and animation structure. The hierarchical model is then used to fuse multiple shape cues from silhouette, stereo and sparse feature data in a coarse-to-fine strategy to recover a model that reproduces the appearance in the images. The framework is compared to physics-based deformable surface fitting at a single resolution, demonstrating an improved reconstruction accuracy against ground-truth data with a reduced model distortion. Results demonstrate realistic modelling of real people with accurate shape and appearance while preserving model structure for use in animation.
A picture is worth a thousand keywords: exploring mobile image-based web search
Authors: Konrad Tollmar, Ted Möller, Björn Nilsved
Venue: Proceedings of the 9th international conference on Human computer interaction with mobile devices and services (2007)

Images of objects as queries is a new approach to search for information on the web. Image-based information retrieval goes beyond only matching images, as information in other modalities also can be extracted from data collections using image search. We have developed a new system that uses images to search for web-based information. This paper has a particular focus towards exploring user's experience of general mobile image-based Web searches to find what issues and phenomena it contains. This was achieved in a multi-part study by creating and letting respondents test prototypes of mobile image-based search systems and collecting data using interviews, observations, video-observations, and questionnaires. We observed that searching for information only based on visual similarity and without any assistance is sometimes difficult, especially on mobile devices with limited interaction bandwidth. Most of our subjects preferred a search tool that guides the users through the search result based on contextual information, compared to presenting the search result as a plain ranked list.
Perfect Simulation of a Class of Stochastic Hybrid Systems with an Application to Peer to Peer Systems
Authors: Bruno Gaujal, Florence Perronnin, Rémi Bertin
Venue: Discrete Event Dynamic Systems (2008)

In this paper we present a class of hybrid systems made of deterministic differential equations and random discrete jumps. We then show how to construct a simulation of such a stochastic hybrid system that provides perfect samples of its asymptotic behavior based on the extension to continuous state-space of coupling-from-the-past techniques introduced by Foss and Tweedie (Stoch Models 14:187---204, 1998) and using suitable envelope trajectories to tackle non-monotonicity. The applicability of the method is illustrated by showing how this framework can be used to model the Squirrel peer to peer system and by reporting a simulation study based on this approach. This paper provides both a framework on how to carry simulation based experimental studies of large and complex hybrid systems and its application in the Squirrel model demonstrating how versatile and powerful this approach can be over a typical example.
Total domination of graphs and small transversals of hypergraphs
Authors: St&#x00e9;phan Thomass&#x00e9;, Anders Yeo
Venue: Combinatorica (2007)

The main result of this paper is that every 4-uniform hypergraph on n vertices and m edges has a transversal with no more than (5n + 4m)/21 vertices. In the particular case n = m, the transversal has at most 3n/7 vertices, and this bound is sharp in the complement of the Fano plane. Chv&#x00e1;tal and McDiarmid [5] proved that every 3-uniform hypergraph with n vertices and edges has a transversal of size n/2. Two direct corollaries of these results are that every graph with minimal degree at least 3 has total domination number at most n/2 and every graph with minimal degree at least 4 has total domination number at most 3n/7. These two bounds are sharp.
On the complexity of fixed parameter problems
Authors: K. R. Abrahamson
Venue: Proceedings of the 30th Annual Symposium on Foundations of Computer Science (1989)

The authors address the question of why some fixed-parameter problem families solvable in polynomial time seem to be harder than others with respect to fixed-parameter tractability: whether there is a constant alpha such that all problems in the family are solvable in time O(n/sup alpha /). The question is modeled by considering a class of polynomially indexed relations. The main results show that (1) this setting supports notions of completeness that can be used to explain the apparent hardness of certain problems with respect to fixed-parameter tractability, and (2) some natural problems are complete.
March of the (virtual) machines: past, present, and future milestones in the adoption of virtualization in computing education
Authors: Alessio Gaspar, Sarah Langevin, William D. Armitage, Matt Rideout
Venue: Journal of Computing Sciences in Colleges (2008)

Many courses in the computing curricula can benefit from hands-on pedagogical activities (e.g. active, discovery or problem-based learning) in the form of laboratory components associated with the lectures. While the benefits of such hands-on learning sessions are generally agreed upon, some system-oriented courses present a non-trivial challenge to instructors. Operating systems concepts (OSC), system administration, networking (NET) and computer security are all examples of courses which laboratories require students to have root access to be able to engage in meaningful experimentation of the lecture's concepts. With this constraint comes the need for more flexible technological support in the classroom. This paper reviews how virtualization has penetrated the computing educational practices over the past 3 years and identifies milestones toward its efficient integration. Our focus is on leveraging virtualization along with clustering technologies to provide an inexpensive, scalable, on-demand and transparent virtualization environment to students. We discuss technological alternatives to main vendors' offering based on our experience with the SOFTICE project. We conclude by presenting a prototype which extends further our objectives and discuss its potential for a GRID enabled version of our work.
Numerical solution of two asset jump diffusion models for option valuation
Authors: Simon S. Clift, Peter A. Forsyth
Venue: Applied Numerical Mathematics (2008)

Under the assumption that two financial assets evolve by correlated finite activity jumps superimposed on correlated Brownian motion, the value of a contingent claim written on these two assets is given by a two-dimensional parabolic partial integro-differential equation (PIDE). An implicit, finite difference method is derived in this paper. This approach avoids a dense linear system solution by combining a fixed point iteration scheme with an FFT. The method prices both American and European style contracts independent (under some simple restrictions) of the option payoff and distribution of jumps. Convergence under the localization from the infinite to a finite domain is investigated, as are the theoretical conditions for the stability of the discrete approximation under maximum and von Neumann analysis. The analysis shows that the fixed point iteration is rapidly convergent under typical market parameters. The rapid convergence of the fixed point iteration is verified in some numerical tests. These tests also indicate that the method used to localize the PIDE is inexpensive and easily implemented.
Truth Discovery with Multiple Conflicting Information Providers on the Web
Authors: Xiaoxin Yin, Jiawei Han, Philip S. Yu
Venue: IEEE Transactions on Knowledge and Data Engineering (2008)

The world-wide web has become the most important information source for most of us. Unfortunately, there is no guarantee for the correctness of information on the web. Moreover, different web sites often provide conflicting information on a subject, such as different specifications for the same product. In this paper we propose a new problem called Veracity, i.e., conformity to truth, which studies how to find true facts from a large amount of conflicting information on many subjects that is provided by various web sites. We design a general framework for the Veracity problem, and invent an algorithm called TruthFinder, which utilizes the relationships between web sites and their information, i.e., a web site is trustworthy if it provides many pieces of true information, and a piece of information is likely to be true if it is provided by many trustworthy web sites. An iterative method is used to infer the trustworthiness of web sites and the correctness of information from each other. Our experiments show that TruthFinder successfully finds true facts among conflicting information, and identifies trustworthy web sites better than the popular search engines.
Characterizations and construction of Poisson/symplectic and symmetric multi-revolution implicit Runge--Kutta methods of high order
Authors: Min Li, Aiguo Xiao
Venue: Applied Numerical Mathematics (2008)

This paper deals with the characterizations and construction of Poisson/symplectic and (@f^-^1)-symmetric implicit high-order multi-revolution Runge-Kutta methods (MRRKMs). The basic tool is a modified W-transformation based on quadrature formulas and orthogonal polynomials. Two sufficient conditions can be obtained under which MRRKMs are Poisson/symplectic or (@f^-^1)-symmetric. We construct two classes of high order implicit MRRKMs by using these sufficient conditions. Our results can be considered as an extension of related results of the standard Runge-Kutta methods in some references.
A new region filtering and region weighting approach to relevance feedback in content-based image retrieval
Authors: Deok-Hwan Kim, Seung-Hoon Yu
Venue: Journal of Systems and Software (2008)

A new region filtering and region weighting method, which filters out unnecessary regions from images and learns region importance from the region size and the spatial location of regions in an image, is proposed based on region representations. It weights the regions optimally and improves the performance of the region-based retrieval system based on relevance feedback. Due to the semantic gap between the low level feature representation and the high level concept in a query image, semantically relevant images may exhibit very different visual characteristics, and may be scattered in several clusters in the feature space. Our main goal is finding semantically related clusters and their weights to reduce this semantic gap. Experimental results demonstrate the efficiency and effectiveness of the proposed region filtering and weighting method in comparison with the area percentage method and region frequency weighted by inverse image frequency method, respectively.
Improving Web search using image snippets
Authors: Xiao-Bing Xue, Zhi-Hua Zhou, Zhongfei (Mark) Zhang
Venue: ACM Transactions on Internet Technology (TOIT) (2008)

The Web has become the largest information repository in the world; thus, effectively and efficiently searching the Web becomes a key challenge. Interactive Web search divides the search process into several rounds, and for each round the search engine interacts with the user for more knowledge of the user's information requirement. Previous research mainly uses the text information on Web pages, while little attention is paid to other modalities. This article shows that Web search performance can be significantly improved if imagery is considered in interactive Web search. Compared with text, imagery has its own advantage: the time for &ldquo;reading&rdquo; an image is as little as that for reading one or two words, while the information brought by an image is as much as that conveyed by a whole passage of text. In order to exploit the advantages of imagery, a novel interactive Web search framework is proposed, where image snippets are first extracted from Web pages and then provided, along with the text snippets, to the user for result presentation and relevance feedback, as well as being presented alone to the user for image suggestion. User studies show that it is more convenient for the user to identify the Web pages he or she expects and to reformulate the initial query. Further experiments demonstrate the promise of introducing multimodal techniques into the proposed interactive Web search framework.
Information and Quality Assurance: An Unsolved, Perpetual Problem for Past and Future Generations
Authors: Jeffrey Voas, Linda Wilbanks
Venue: IT Professional (2008)

Quality assurance is well understood in the hardware/manufacturing community but not necessarily within the software community. The meaning of Information assurance depends on who you ask; those in the computer security field interpret information assurance as the need to protect the information, those in quality assurance relate information assurance to the quality of the information. Software assurance ranks even poorer in understanding; although most would agree that it relates to quality, they would be unsure what that means. System assurance is well understood due to its basis on known systems-engineering principles, tending to emphasize the dichotomy of hardware and software concept understanding. In this issue, three articles address parts of the assurance puzzle, which includes: quality assurance, information assurance, software assurance, and system assurance. The combination of these four builds the argument for trust, which is the sole reason for building assurances. To help avoid costly mismatches, consider looking at which part of the assurance puzzle you need solved first before looking at supposed assurance solutions.
Modeling and optimization of transmission schemes in energy-constrained wireless sensor networks
Authors: Ritesh Madan, Shuguang Cui, Sanjay Lall, Andrea J. Goldsmith
Venue: IEEE/ACM Transactions on Networking (TON) (2007)

We consider a wireless sensor network with energy constraints. We model the energy consumption in the transmitter circuit along with that for data transmission. We model the bottom three layers of the traditional networking stack--the link layer, the medium access control (MAC) layer, and the routing layer. Using these models, we consider the optimization of transmission schemes to maximize the network lifetime. We first consider the optimization of a single layer at a time, while keeping the other layers fixed. We make certain simplifying assumptions to decouple the layers and formulate optimization problems to compute a strategy that maximizes the network lifetime. We then extend this approach to cross-layer optimization of time division multiple access (TDMA) wireless sensor networks. In this case, we construct optimization problems to compute the optimal transmission schemes to an arbitrary degree of accuracy and efficiently. We then consider networks with interference, and propose methods to compute approximate solutions to the resulting optimization problems. We give numerical examples that illustrate the computational approaches as well as the benefits of cross-layer design in wireless sensor networks.
Brief paper: Global stabilization of a class of partially known nonnegative systems
Authors: Ludovic Mailleret, Jean-Luc Gouzé, Olivier Bernard
Venue: Automatica (Journal of IFAC) (2008)

In this paper we deal with the problem of global output feedback stabilization of a class of n-dimensional nonlinear nonnegative systems possessing a one-dimensional analytically unknown part that is also a measured output. We first propose our main result, an output feedback control procedure, taking advantage of measurements of the uncertain part, able to globally stabilize the system toward an adjustable equilibrium point in the positive orthant. Though quite general, this result is based on hypotheses that might be difficult to check in practice. Then in a second step, through a theorem on a class of nonnegative systems linking the existence of a positive equilibrium to its global asymptotic stability, we propose other hypotheses for our main result to hold. These new hypotheses are more restrictive but much simpler to check. An illustrative example highlights both the potentially complex open loop dynamics of the considered systems and the interesting characteristics of the control procedure.
Deployment and Interoperability of the Phosphorus Grid Enabled GMPLS (G2MPLS) Control Plane
Authors: E. Escalona, G. Zervas, R. Nejabati, D. Simeonidou, G. Markidis, A. Tzanakaki, G. Carrozzo, N. Ciulli, B. Belter, A. Binczewski
Venue: Proceedings of the 2008 Eighth IEEE International Symposium on Cluster Computing and the Grid (2008)

Grid-GMPLS (G2MPLS) is conceived as a powerful Network Control Plane solution that enhances the standard ASON/GMPLS architecture providing single-step resource reservation, co-allocation and maintenance of both network and Grid resources. This paper identifies and discusses the main issues and considerations that arise by Network Research and Educational Networks and network operators in order to facilitate the dissemination of G2MPLS Control Plane. Interoperability issues and backwards compatibility with existing Network Control Planes centre the scope of this study, which intends to demonstrate the feasibility of adopting the proposed architectures.
Additive approximation for bounded degree survivable network design
Authors: Lap Chi Lau, Mohit Singh
Venue: Proceedings of the 40th annual ACM symposium on Theory of computing (2008)

We study a general network design problem with additional degree constraints. Given connectivity requirements ruv for all pairs of vertices, a Steiner network is a graph in which there are at least ruv edge-disjoint paths between u and v for all pairs of vertices u,v. In the MINIMUM BOUNDED-DEGREE STEINER NETWORK problem, we are given an undirected graph G with an edge cost for each edge, a connectivity requirement ruv for each pair of vertices u and v, and a degree upper bound for each vertex v. The task is to find a minimum cost Steiner network which satisfies all the degree upper bounds. The aim of this paper is to design approximation algorithms that minimize the total cost and the degree violation simultaneously. Our main results are the following: There is a polynomial time algorithm which returns a Steiner forest of cost at most 2 OPT and the degree violation at each vertex is at most 3 ,where OPT is the cost of an optimal solution which satisfies all the degree bounds. There is a polynomial time algorithm which returns a Steiner network of cost at most 2 OPT and the degree violation at each vertex is at most 6r max +3 ,where OPT is the cost of an optimal solution which satisfies all the degree bounds, and r max := max u,v {r uv}. These results achieve the best known guarantees for both the total cost and the degree violation simultaneously. As corollaries, these results provide the first additive approximation algorithms for finding low degree subgraphs including Steiner forests, k -edge-connected subgraphs, and Steiner networks. The algorithms develop on the iterative relaxation method applied to a natural linear programming relaxation as in [10, 16, 22]. The new algorithms avoid paying a multiplicative factor of two on the degree bounds even though the algorithm can only pick edges with fractional value 1/2 . This is based on a stronger characterization of the basic so-algorithm is nearly tight.
A Mathematical Architecture for Molecular Computing
Authors: Robert J. Bonneau, George Ramseyer, Tom Renz, Claire Thiem
Venue: Proceedings of the 36th Applied Imagery Pattern Recognition Workshop (2007)

Traditional computing uses transistors and binary logic in order to perform computing operations. This approach has proved successful as long as the number of transistors per integrated circuit can be scaled to accommodate increasing speed and heat requirements. Unfortunately, this approach does not allow speeds above the limit where the size of the transistors approaches the limit of the integrated circuit substrates’ molecular size. In this condition, electrons cannot reliably be contained within the boundaries separating one transistor from the next and increasingly small circuits become impractical. The current solution to this dilemma is to increase the number of functional units on an integrated circuit and thereby eliminate the need for increasingly small transistors. However whether we increase the number of functional units or the speed, there are inherent limitations in the number of transistors we can put onto one chip. We therefore look to another functional approach to generate the next generation of integrated circuits. We therefore look to using the molecules and elementary particles themselves as a means of computation. In order to accomplish molecular computation we need to modify the model of traditional computation from a transistor based binary method to analog based arbitrary basis model. This approach is not unknown since optical computation among other has used analog processing for highly parallel computation. The issue with molecular and quantum computing methods has traditionally been that understanding the state the computing function itself is often subject to high degree uncertainty. This uncertainty is not unexpected since the number of possible states that can exist when electromagnetic energy interrogates a collection of molecules, atoms, or electrons is quite large. In order to develop a method of representing these states we use a partially observable Markov decision process. We will then develop a finite state machine approach to computation based on a model for our molecular or quantum system.