206394981
On interactive communication
Ahlswede has previously introduced an abstract correlated source (/spl Vscr//spl times//spl Wscr/,S) with outputs (/spl upsi/, /spl omega/)/spl isin/S/spl sub//spl Vscr//spl times//spl Wscr/, where persons P/sub /spl Vscr// and P/sub /spl Wscr// observe /spl upsi/ and /spl omega/, respectively. More recently, Orlitsky considered the minimal number C/sub m/ of bits to be transmitted in m rounds to "inform P/sub /spl Wscr// about /spl upsi/ over one channel." He showed that C/sub 2//spl les/4C/sub /spl infin//+3 and that in general C/sub 2/NOT/spl sim/C/sub /spl infin//. We give a simple example for C/sub 3/NOT/spl sim/C/sub /spl infin//. However, for the new model "inform P/sub /spl Wscr// over two channels", four rounds are optimal for this example-a result we conjecture in general. If both P/sub /spl Vscr// and P/sub /spl Wscr// are to be informed over two channels about the other outcome, we determine asymptotically the complexities for all sources. In our last model "inform P/sub /spl Vscr// and P/sub /spl Wscr// over one channel" for all sources the total number T/sub 2/ of required bits is known asymptotically and T/sub /spl infin// is bounded from below in terms of average degrees. There are exact results for several classes of regular sources. An attempt is made to discuss the methods of the subject systematically.
15006226
Bounds on the sizes of constant weight covering codes
Motivated by applications in universal data compression algorithms we study the problem of bounds on the sizes of constant weight covering codes. We are concerned with the minimal sizes of codes of lengthn and constant weightu such that every word of lengthn and weightv is within Hamming distanced from a codeword. In addition to a brief summary of part of the relevant literature, we also give new results on upper and lower bounds to these sizes. We pay particular attention to the asymptotic covering density of these codes. We include tables of the bounds on the sizes of these codes both for small values ofn and for the asymptotic behavior. A comparison with techniques for attaining bounds for packing codes is also given. Some new combinatorial questions are also arising from the techniques.
43476378
Partial converse for a relay channel
A special case of the general discrete memoryless relay channel is studied. This channel consists of an input x, a relay output z, a channel output y, and a noiseless channel of capacity C/sub r/ allowing the relay sender to send additional information to the decoder. The channel is described by a collection of distributions (p(y, z mod x)). The decoder uses the channel output y and a function f(z) of the relay output at a rate no greater than C/sub r/ to recover the message. Some results on the capacity of the channel are obtained. >
32850524
Linear inequalities for covering codes: Part I: Pair covering inequalities
The lower bounds on K(n,R), minimum number of codewords of any binary code of length n, and covering radius R are improved. A new technique combining the Hamming association scheme and the results of a classic problem of covering pairs by k-tuples is introduced. The new lower bounds are obtained by studying various linear inequalities satisfied by covering codes, and such an inequality is derived. The lower bounds for K(n,R) are studied for some special values of n and R, which serve as examples showing how the methods developed are applied to concrete cases. >
32960689
On Maximal Shadows of Members in Left-compressed Sets
Whereas Stanley, Proctor and others studied Sperner properties of the poset L(k,m) we consider shadows of left-compressed sets and derive asymptotic bounds on their sizes.
6153081
Zero-Error Capacity for Models with Memory and the Enlightened Dictator Channel
Summary form only given. We present a general class of "combinatorial" 0-error capacity problems with the "memory" covering known and many new cases. This class can be incorporated into a model of channels with memory. W analyse a seemingly basic channel in this class, which we call the "dictator channel". Clearly, a dictator always follows his own opinion. However, we speak of an enlightened dictator, if he responds to the unanimous vote of the people against his opinion to the degree, in this case he reaches a decision by coin tossing.
8041199
Scheduling in buffered WDM packet switching networks with arbitrary wavelength conversion capability
Optical networking is a promising candidate for high-speed communication networks because of its huge bandwidth. In this paper we study optimal scheduling in buffered WDM packet switching networks with arbitrary wavelength conversion ability. We focus on limited range wavelength conversion while considering full range wavelength conversion as a special case of it. We formalize the problem of maximizing network throughput and minimizing total delay in such a network as finding an optimal matching in a weighted bipartite graph. We then give a simple and fast algorithm called the scan and swap algorithm that solves the problem in O(kB/sup 2/) time, where k is the number of wavelengths per fiber and B is the buffer length, as compared to other existing algorithms that need at least O(k/sup 2/B/sup 2/ + k/sup 2/BN) time where N is the number of input fibers.
5416143
A clustering based approach to efficient image retrieval
This paper addresses the issue of effective and efficient content based image retrieval by presenting a novel indexing and retrieval methodology that integrates color, texture, and shape information for the indexing and retrieval, and applies these features in regions obtained through unsupervised segmentation, as opposed to applying them to the whole image domain. In order to address the typical color feature "inaccuracy" problem in the literature, fuzzy logic is applied to the traditional color histogram to solve for the problem to a certain degree. The similarity is defined through a balanced combination between global and regional similarity measures incorporating all the features. In order to further improve the retrieval efficiency, a secondary clustering technique is developed and employed to significantly save query processing time without compromising the retrieval precision. An implemented prototype system has demonstrated a promising retrieval performance for a test database containing 2000 general-purpose color images, as compared with its peer systems in the literature.
10250672
Robust and Rapid Generation of Animated Faces from Video Images: A Model-Based Modeling Approach
We have developed an easy-to-use and cost-effective system to construct textured 3D animated face models from videos with minimal user interaction. This is a particularly challenging task for faces due to a lack of prominent textures. We develop a robust system by following a model-based approach: we make full use of generic knowledge of faces in head motion determination, head tracking, model fitting, and multiple-view bundle adjustment. Our system first takes, with an ordinary video camera, images of a face of a person sitting in front of the camera turning their head from one side to the other. After five manual clicks on two images to indicate the position of the eye corners, nose tip and mouth corners, the system automatically generates a realistic looking 3D human head model that can be animated immediately (different poses, facial expressions and talking). A user, with a PC and a video camera, can use our system to generate his/her face model in a few minutes. The face model can then be imported in his/her favorite game, and the user sees themselves and their friends take part in the game they are playing. We have demonstrated the system on a laptop computer live at many events, and constructed face models for hundreds of people. It works robustly under various environment settings.
6431749
Reasoning with Multimedia Information Using Symbolic Projection
In many multimedia application systems, it is not the final goal to retrieve the relevant multimedia information from different multimedia information sources. Rather, post-processing of the retrieved multimedia information is needed. For example, the retrieved information is used as "known facts". The systems will do some reasoning to obtain further conclusions based on these multimedia form "known facts". We call this reasoning with multimedia information. Most current research work in multimedia information processing is focused on multimedia information retrieval, but post-processing the retrieved information is more or less ignored. This paper explores the way to tackle this problem by using symbolic projection. A case study of reasoning with still image information is presented. Some extensions to symbolic projection-introducing auxiliary pictorial objects in symbolic pictures that need to be processed-are discussed. We expect this paper will stimulate further research on this important but ignored topic.
14282413
Distance-adaptive update protocols for scalable shared-memory multiprocessors
While update protocols generally induce lower miss rates than invalidate protocols, they tend to generate much traffic. This is one of the reasons why they are considered less cost-effectively scalable than invalidate protocols and, as a result, are avoided in most existing designs of scalable shared-memory multiprocessors. However, given the increasing relative cost of cache misses, update protocols are becoming more worthy of exploration. In this paper, we present a model of sharing that is key to investigating the performance of optimized update protocols: the update distance model. The model gives insight into the update patterns that optimized protocols need to handle. Using this model, we design a new family of protocols that we call distance-adaptive protocols. In these schemes, the directory records the update patterns observed and then uses them to selectively send updates and invalidations to processors. As a result, traffic and miss rates are kept low. We present an implementation of these protocols based on a dynamic pointer scheme. A performance comparison between one of these protocols and efficient invalidate and delayed competitive-update protocols over five applications shows that the new protocol decreases the execution time by an average of 15% and 10% respectively.