ppxscal/embedding_network huggingface dataset:
On the Best Rank-1 and Rank-(R1,R2,. . .,RN) Approximation of Higher-Order Tensors
Authors: Lieven De Lathauwer, Bart De Moor, Joos Vandewalle
Venue: SIAM Journal on Matrix Analysis and Applications (2000)

In this paper we discuss a multilinear generalization of the best rank-R approximation problem for matrices, namely, the approximation of a given higher-order tensor, in an optimal least-squares sense, by a tensor that has prespecified column rank value, row rank value, etc. For matrices, the solution is conceptually obtained by truncation of the singular value decomposition (SVD); however, this approach does not have a straightforward multilinear counterpart. We discuss higher-order generalizations of the power method and the orthogonal iteration method.
Normalized Cuts and Image Segmentation
Authors: Jianbo Shi, Jitendra Malik
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

We propose a novel approach for solving the perceptual grouping problem in vision. Rather than focusing on local features and their consistencies in the image data, our approach aims at extracting the global impression of an image. We treat image segmentation as a graph partitioning problem and propose a novel global criterion, the normalized cut, for segmenting the graph. The normalized cut criterion measures both the total dissimilarity between the different groups as well as the total similarity within the groups. We show that an efficient computational technique based on a generalized eigenvalue problem can be used to optimize this criterion. We have applied this approach to segmenting static images, as well as motion sequences, and found the results to be very encouraging.
On universally easy classes for NP-complete problems
Authors: Erik D. Demaine, Alejandro López-Ortiz, J. Ian Munro
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

We explore the natural question of whether all NP-complete problems have a common restriction under which they are polynomially solvable. More precisely, we study what languages are universally easy in that their intersection with any NP-complete problem is in P. In particular, we give a polynomial-time algorithm to determine whether a regular language is universally easy. While our approach is language-theoretic, the results bear directly on finding polynomial-time solutions to very broad and useful classes of problems.
An algorithm for the approximate solution of Wiener-Hopf integral equations
Authors: Frank Stenger
Venue: Communications of the ACM (1973)

An explicit approximate solution &fnof;(h)&agr; is given for the equation &fnof;(t) = &int;&infin;0 k(t - &tgr;)&fnof;(&tgr;) d&tgr; + g(t), t > 0, (*) where k, g &isin; L1(- &infin;, &infin;) &cap; L2(-&infin;, &infin;), and where it is assumed that the classical Wiener-Hopf technique may be applied to (*) to yield a solution &fnof; &isin; L1(0, &infin;) &cap; L2(0, &infin;) for every such given g. It is furthermore assumed that the Fourier transforms K and G+ of k and g respectively are known explicitly, where K(x) = &int;&infin;-&infin; exp (ixt)k(t) dt, G+(x) = &int;&infin;0 exp (ixt)g(t) dt. The approximate solution &fnof;(h)&agr; of (*) depends on two positive parameters, h and &agr;. If K(z) and G+(z) are analytic functions of z = x + iy in the region {x + iy : | y | &le; d}, and if K is real on (-&infin;, &infin;), then | &fnof;(t) - &fnof;(h)&agr;(t) | &le; c1 exp (-&pgr;d/h) + c2 exp (-&pgr;d/&agr;) where c1 and c2 are constants. As an example, we compute &fnof;(h)&agr;(t), t = 0.2(0.2)1, h = &pgr;/10, &agr; = &pgr;/50, for the case of k(t) = exp(-| t |)/(2&pgr;), g(t) = t4 exp (-3t). The resulting solution is correct to five decimals.
Optimal constrained graph exploration
Authors: Christian A. Duncan, Stephen G. Kobourov, V. S. Anil Kumar
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

We address the problem of exploring an unknown graph G = (V, E) from a given start node s with either a tethered robot or a robot with a fuel tank of limited capacity, the former being a tighter constraint. In both variations of the problem, the robot can only move along the edges of the graph, i.e, it cannot jump between non-adjacent vertices. In the tethered robot case, if the tether (rope) has length l, then the robot must remain within distance l from the start node s. In the second variation, a fuel tank of limited capacity forces the robot to return to s after traversing C edges. The efficiency of algorithms for both variations of the problem is measured by the number of edges traversed during the exploration. We present an algorithm for a tethered robot which explores the graph in &Ogr;(&brvbar;E&brvbar;) edge traversals. The problem of exploration using a robot with a limited fuel tank capacity can be solved with a simple reduction from the tethered robot case and also yields a &Ogr;(&brvbar;E&brvbar;) algorithm. This improves on the previous best known bound of &Ogr;(&brvbar;E&brvbar; + &brvbar;V&brvbar;log 2&brvbar;V&brvbar;) in [4]. Since the lower bound for the graph exploration problems is &brvbar;E&brvbar;, our algorithm is optimal, thus answering the open problem of Awerbuch, Betke, Rivest, and Singh [3].
Mosaicing on Adaptive Manifolds
Authors: Shmuel Peleg, Benny Rousso, Alex Rav-Acha, Assaf Zomet
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

Image mosaicing is commonly used to increase the visual field of view by pasting together many images or video frames. Existing mosaicing methods are based on projecting all images onto a predetermined single manifold: A plane is commonly used for a camera translating sideways, a cylinder is used for a panning camera, and a sphere is used for a camera which is both panning and tilting. While different mosaicing methods should therefore be used for different types of camera motion, more general types of camera motion, such as forward motion, are practically impossible for traditional mosaicing. A new methodology to allow image mosaicing in more general cases of camera motion is presented. Mosaicing is performed by projecting thin strips from the images onto manifolds which are adapted to the camera motion. While the limitations of existing mosaicing techniques are a result of using predetermined manifolds, the use of more general manifolds overcomes these limitations.
Hill-climbing finds random planted bisections
Authors: Ted Carson, Russell Impagliazzo
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

We analyze the behavior of hill-climbing algorithms for the minimum bisection problem on instances drawn from the &ldquo;planted bisection&rdquo; random graph model, Gn,p,q, previously studied in [3, 4, 10, 11, 14, 9, 7]. This is one of the few problem distributions for which various popular heuristic methods, such as simulated annealing, have been proven to succeed. However, it has been open whether these sophisticated methods were necessary, or whether simpler heuristics would also work. Juels [14] made the first progress towards an answer by showing that simple hill-climbing does suffice for very wide separations between p and q. Here we give a more complete answer. A simple, polynomial-time, hill-climbing algorithm for this problem is given and shown to succeed in finding the planted bisection with high probability if p - q = &OHgr; (n-&frac12;ln3n). For dense graphs, this matches the condition for optimality of the planted bisection to within a polylogarithmic factor. Furthermore, we show that a generic randomized hill-climbing algorithm succeeds in finding the planted bisection in polynomial time if p - q = &OHgr; (n-&frac14; ln3 n), for any &isin; > 0. This algorithm, studied also by [14], is a degenerate case of both Metropolis and go-with-the-winners, and the range here properly includes those analyzed in [11, 9, 14]. So this result implies, extends, and unifies those from [11, 9, 14]. Thus, to get a provable distinction between simulated annealing and hill-climbing for natural problems will require considerable progress both on new positive results for SA and new negative results for hill-climbing methods.
Experimental evaluation of filter effectiveness (extended abstract)
Authors: Lixian Han, Hongjun Zhu, Jianwen Su
Venue: Proceedings of the 8th ACM international symposium on Advances in geographic information systems (2000)

Evaluation of a spatial join typically has two steps: a filter step that applies the join on approximations of spatial objects and a refinement step that determines the actual intersection of two spatial objects. In this paper, we study the effectiveness of filters with different approximations including minimum bounding rectangles, rectilinear approximations, minimum 5-corner bounding convex polygons, and convex hulls. We compare the effectiveness of filters by comparing the number of &ldquo;false hits&rdquo; in the filter result using these approximations. We analyze the impact of parameters such as approximation quality and aspect ratios of input polygons on the filter effectiveness.
Bounded context syntactic analysis
Authors: Robert W. Floyd
Venue: Communications of the ACM (1964)

Certain phase structure grammars define languages in which the phrasehood and structure of a substring of a sentence may be determined by consideration of only a bounded context of the substring. It is possible to determine, for any specified bound on the number of contextual characters considered, whether a given grammar is such a bounded context grammar. Such grammars are free from syntactic ambiguity. Syntactic analysis of sentences in a bounded context language may be performed by a standard process and requires a number of operations proportional to the length of sentence analyzed. Bounded context grammars form models for most languages used in computer programming, and many methods of syntactic analysis, including analysis by operator precedence, are special cases of bounded context analysis.
Parallel VHDL simulation
Authors: E. Naroska
Venue: Proceedings of the conference on Design, automation and test in Europe (1998)

In this paper we evaluate parallel VHDL simulation based on conservative parallel discrete event simulation (conservative PDES) algorithms. We focus on a conservative simulation algorithm based on critical and external distances. This algorithm exploits the interconnection structure within the simulation model to increase parallelism. Further, a general method is introduced to automatically transform a VHDL model into a PDES model. Additionally, we suggest a method to further optimize parallel simulation performance. Finally, our first simulation results on a IBM parallel computer are presented. While these results are not sufficient for a general evaluation they show that a good speedup can be obtained.
Designing domain-specific processors
Authors: Marnix Arnold, Henk Corporaal
Venue: Proceedings of the ninth international symposium on Hardware/software codesign (2001)

We present a semi-automated method for the detection and exploitation of application domain specific instruction set extensions for embedded (VLIW) processors. It consists of three steps: the first step detects frequently occurring operation patterns, in the second step, the patterns are grouped and implemented in a number of Special Function Units (SFUs) and the third step incorporates the custom operations into the code generation process. Experiments show that the SFUs generated and exploited with our methodology can result in architectures that perform up to 30% better than architectures of the same cost without SFUs.
Branch Points in One-Dimensional Gaussian Scale Space
Authors: Peter Johansen, Mads Nielsen, Ole Fogh Olsen
Venue: Journal of Mathematical Imaging and Vision (2000)

Scale space analysis combines global and local analysis in a single methodology by simplifying a signal. The simplification is indexed using a continuously varying parameter denoted scale. Different analyses can then be performed at their proper scale. We consider evolution of a polynomial by the parabolic partial differential heat equation. We first study a basis for the solution space, the heat polynomials, and subsequently the local geometry around a branch point in scale space. By a branch point of a polynomium we mean a scale and a location where two zeros of the polynomial merge. We prove that the number of branch points for a solution is \lfloor\frac{n}{2}\rfloor for an initial polynomial of degree n. Then we prove that the branch points uniquely determine a polynomial up to a constant factor. Algorithms are presented for conversion between the polynomial's coefficients and its branch points.
Security problems in the TCP/IP protocol suite
Authors: S. M. Bellovin
Venue: ACM SIGCOMM Computer Communication Review (1989)

The TCP/IP protocol suite, which is very widely used today, was developed under the sponsorship of the Department of Defense. Despite that, there are a number of serious security flaws inherent in the protocols, regardless of the correctness of any implementations. We describe a variety of attacks based on these flaws, including sequence number spoofing, routing attacks, source address spoofing, and authentication attacks. We also present defenses against these attacks, and conclude with a discussion of broad-spectrum defenses such as encryption.
Standards: Heading format for data transmission (A USAAI) tutorial
Authors: E. Lohse
Venue: Communications of the ACM (1968)

This paper is for information purposes and is intended as a comprehensive thought-provoking collection of the major aspects and considerations influencing Heading Format for Data Transmission. Information processing systems of today have outgrown the confines of the attended and isolated system environment. They now perform information interchange via communication networks, often with many real-time aspects. This interconnection of information processing systems via communciations networks requires that the two (or mo re) stations performing information interchange operate by agreed upon information formats. It is the intent of this paper to discuss the uses and organization of all known items that might be included in one type of information format: Heading Format. This paper is an attempt to provide an all-inclusive list of heading format items, thoroughly describle and discuss each item, and arrange the items in a logical sequence. This will establish a comprehensive heading format item sequencing list that individual message transfer systems may draw on to obtain consistent and usable message formats. It is not proposed that all heading format items or even that any one particular heading format item be mandatory for any system. This paper explores the implications of the use of heading format for generalized information generalized information interchaneg and the criteria on which a future heading format standard could be based. The following guidelines were used as a basis for the Task Group's work on message formats. The initial goal of the Task Group should be to prepare a tutorial paper on message formats. In the future, the Task Group may wish to prepare a standard covering message formats if this is found to be desirable. The Task Group should avoid message format (heading) definitions that are too narrow in scope; that is, a message heading should not be defined in such a manner that it is only applicable to a relatively small class of systems (e.g. store-and-forward). The doctrine for the use of message headings should be such that, by logical extension, it can meet the needs of communication systems that have different degrees of sophistication.
Finding strongly connected components in parallel in particle transport sweeps
Authors: William Mclendon,  III, Bruce Hendrickson, Steve Plimpton, Lawrence Rauchwerger
Venue: Proceedings of the thirteenth annual ACM symposium on Parallel algorithms and architectures (2001)

Discrete ordinates methods are commonly used to simulate radiation transport for fire or weapons modeling. The computation proceeds by sweeping the flux across a grid. A particular cell cannot be computed until all the cells immediately upwind of it are finished. If the directed dependence graph for the grid cells contains a cycle then sweeping methods will deadlock. This can happen in unstructured grids and time stepped problems where the grid is allowed to deform. In this paper we present a parallel algorithm to detect cycles in the dependence graphs present in these grids as well as an implementation and experimental results on shared and distributed memory machines.
A technique for software module specification with examples
Authors: D. L. Parnas
Venue: Communications of the ACM (1972)

This paper presents an approach to writing specifications for parts of software systems. The main goal is to provide specifications sufficiently precise and complete that other pieces of software can be written to interact with the piece specified without additional information. The secondary goal is to include in the specification no more information than necessary to meet the first goal. The technique is illustrated by means of a variety of examples from a tutorial system.
Communication patterns and models in prism: a spectral element-Fourier parallel Navier-Stokes solver
Authors: Constantinos Evangelinos, George Em Karniadakis
Venue: Proceedings of the 1996 ACM/IEEE conference on Supercomputing (CDROM) (1996)

In this paper we analyze communication patterns in the parallel three-dimensional Navier-Stokes solver Prism, and present performance results on the IBM SP2, the Cray T3D and the SGI Power Challenge XL. Prism is used for direct numerical simulation of turbulence in non-separable and multiply-connected domains. The numerical method used in the solver is based on mixed spectral element-Fourier expansions in (x-y) planes and z-direction, respectively. Each (or a group) of Fourier modes is computed on a separate processor as the linear contributions (Helmholtz solves) are completely uncoupled in the incompressible Navier-Stokes equations; coupling is obtained via the nonlinear contributions (convective terms). The transfer of data between physical and Fourier space requires a series of complete exchange operations, which dominate the communication cost for small number of processors. As the number of processors increases, global reduction and gather operations become important while complete exchange becomes more latency dominated. Predictive models for these communication operations are proposed and tested against measurements. A relatively large variation in communication timings per iteration is observed in simulations and quantified in terms of specific operations. A number of improvements are proposed that could significantly reduce the communications overhead with increasing numbers of processors, and {\em generic} predictive maps are developed for the complete exchange operation, which remains the fundamental communication in Prism. Results presented in this paper are representative of a wider class of parallel spectral and finite element codes for computational mechanics which require similar communication operations.
An integrated environment for knowledge acquisition
Authors: Jim Blythe, Jihie Kim, Surya Ramachandran, Yolanda Gil
Venue: Proceedings of the 6th international conference on Intelligent user interfaces (2001)

This paper describes an integrated acquisition interface that includes several techniques previously developed to support users in various ways as they add new knowledge to an intelligent system. As a result of this integration, the individual techniques can take better advantage of the context in which they are invoked and provide stronger guidance to users. We describe the current implementation using examples from a travel planning domain, and demonstrate how users can add complex knowledge to the system.
Computational challenges in portfolio management
Authors: Martin B. Haugh, Andrew W. Lo
Venue: Computing in Science and Engineering (2001)

The authors describe a relatively simple problem that all investors face-managing a portfolio of financial securities over time to optimize a particular objective function. They show how complex such a problem can become when real-world constraints are incorporated into its formulation.
A modular computer sharing systems
Authors: Herbert B. Baskin, Elsa B. Horowitz, Robert D. Tennison, Larry E. Rittenhouse
Venue: Communications of the ACM (1969)

An alternative approach to the design and organization of a general purpose interactive multiterminal computing system is presented. The system organization described is a conceptually simple arrangement of a bank of interchangeable computers, each of which is a memory/proputor pair, that are assigned to process terminal jobs as they arrive. One of the computers serves as the master or control computer and supervises the collection and distribution of messages from and to the remote terminals. In the simplest form there is a disk drive for each connected terminal. A crosspoint switching network allows any such disk drive to be connected to any computer in the bank, under control of the control computer. Thus, while each active terminal user &ldquo;occupies&rdquo; a dedicated disk drive, he may share the computer with many other terminal users in a simple manner. The ratio of users to computers is dependent on both the size and power of the machines used and the computation requirements of the particular mix of users. This system organization is inherently a simpler and therefore more reliable approach to time-sharing computers and has the potential of a highly available system at relatively low cost. Economic configurations are possible for a range of systems sizes that span at least one order of magnitude. Finally, problem programs developed by remote terminal users can be run on a dedicated batch system if compatible computers are used.
Structure and content-based segmentation of speech transcripts
Authors: Dulce Ponceleon, Savitha Srinivasan
Venue: Proceedings of the 24th annual international ACM SIGIR conference on Research and development in information retrieval (2001)

algorithm for the segmentation of an audio/video source into topically cohesive segments based on automatic speech recognition (ASR) transcriptions is presented. A novel two-pass algorithm is described that combines a boundary-based method with a content-based method. In the first pass, the temporal proximity and the rate of arrival of ngram features is analyzed in order to compute an initial segmentation. In the content- based second pass, changes in content-bearing words are detected by using the ngram features as queries in an information-retrieval system. The second pass validates the initial segments and merges them as needed. Feasibility of the segmentation task can vary enormously depending on the structure of the audio content, and the accuracy of ASR. For real-world corporate training data our method identifies, at worst, a single salient segment of the audio and, at best, a high-level table-of-contents. We illustrate the algorithm in detail with some examples and validate the results with segmentation boundaries generated manually.
A method for locating zeros of complex functions
Authors: George L. Cain,  Jr.
Venue: Communications of the ACM (1966)

A method for computing the index, or winding number, is developed and applied to the problem of finding zeros of functions from the plane into the plane.