2256716
Minimum Membership Set Covering and the Consecutive Ones Property
The Minimum Membership Set Cover problem has recently been introduced and studied in the context of interference reduction in cellular networks. It has been proven to be notoriously hard in several aspects. Here, we investigate how natural generalizations and variations of this problem behave in terms of the consecutive ones property: While it is well-known that classical set covering problems become polynomial-time solvable when restricted to instances obeying the consecutive ones property, we experience a significantly more intricate complexity behavior in the case of Minimum Membership Set Cover. We provide polynomial-time solvability, NP-completeness, and approximability results for various cases here. In addition, a number of interesting challenges for future research is exhibited
14944633
On Exact and Approximation Algorithms for Distinguishing Substring Selection
The NP-complete Distinguishing Substring Selection problem (DSSS for short) asks, given a set of “good” strings and a set of “bad” strings, for a solution string which is, with respect to Hamming metric, “away” from the good strings and “close” to the bad strings.
1715544
Pattern matching for arc-annotated sequences
We study pattern matching for arc-annotated sequences. An O(nm) time algorithm is given for the problem to determine whether a length m sequence with nested arc annotation is an arc-preserving subsequence (aps) of a length n sequence with nested arc annotation, called APS(NESTED,NESTED). Arc-annotated sequences and, in particular, those with nested arc annotation are motivated by applications in RNA structure comparison. Our algorithm generalizes results for ordered tree inclusion problems and it is useful for recent fixed-parameter algorithms for LAPCS(NESTED,NESTED), which is the problem of computing a longest arc-preserving common subsequence of two sequences with nested arc annotations. In particular, the presented dynamic programming methodology implies a quadratic-time algorithm for an open problem posed by Vialette.
6020472
Compression-based fixed-parameter algorithms for feedback vertex set and edge bipartization
We show that the NP-complete Feedback Vertex Set problem, which asks for the smallest set of vertices to remove from a graph to destroy all cycles, is deterministically solvable in O(c^[email protected]?m) time. Here, m denotes the number of graph edges, k denotes the size of the feedback vertex set searched for, and c is a constant. We extend this to an algorithm enumerating all solutions in O(d^[email protected]?m) time for a (larger) constant d. As a further result, we present a fixed-parameter algorithm with runtime O(2^[email protected]?m^2) for the NP-complete Edge Bipartization problem, which asks for at most k edges to remove from a graph to make it bipartite.
14425036
Parameterized Intractability of Distinguishing Substring Selection
Abstract
A central question in computational biology is the design of genetic
markers to distinguish between two given sets of (DNA) sequences. This question is formalized as 
the NP-complete Distinguishing Substring Selection problem (DSSS for short) which asks, given a set of "good" strings and a set of "bad" strings, for a solution string which is, with respect to the Hamming metric, "away" from the good strings and "close" to the bad strings. More precisely, given integers dg, db, and L, we ask for a length-L string s such that s has Hamming distance at least dg to every length-L substring of the good strings and such that every bad string has a length-L substring with Hamming distance at most db to s. Studying the parameterized complexity of DSSS, we show that, already for binary alphabet, DSSS is W[1]-hard with respect to its natural parameters. This, in particular, implies that a recently given polynomial-time approximation scheme (PTAS) by Deng et al. cannot be replaced by a so-called efficient polynomial-time approximation scheme (EPTAS) unless an unlikely collapse in parameterized complexity theory occurs. This is seemingly the first computational biology problem for which such a border between PTAS (which exists) and EPTAS (which is unlikely to exist) could be established. By way of contrast, for a special case of DSSS, we present an exact fixed-parameter algorithm solving the problem efficiently. In this way we also exhibit a sharp border between fixed-parameter tractability and intractability results.

9767043
The Computational Complexity of Avoiding Forbidden Submatrices by Row Deletions
We initiate a systematic study of the ROW DELETION(B) problem on matrices: Given an input matrix A and a fixed "forbidden submatrix" B, the task is to remove a minimum number of rows from A such that no row or column permutation of B occurs as a submatrix in the resulting matrix. An application of this problem can be found, for instance, in the construction of perfect phylogenies. Establishing a strong connection to variants of the NP-complete HITTING SET problem, we describe and analyze structural properties of B that make ROW DELETION(B)NP-complete. On the positive side, the close relation with HITTING SET problems yields constant-factor polynomial-time approximation algorithms and fixed-parameter tractability results.
37890888
Alibaba International: Building a Global Electronic Marketplace
Alibaba is the largest global electronic marketplace (GEM) in the world in terms of its participated users. It was successful due to the factors of China's foreign trade regime, the image of low product cost of China, Alibaba's contingent adaptation to users' changing requirements and e-commerce environments. Alibaba is not a technically mature GEM platform compared with the ideal functions of GEM. Suggested solution for Alibaba to continuing its success is to adopt a novel GEM connectivity model
5572698
Concept exchange: constructing interoperable electronic product catalogues in an emergent environment
Research in interoperability of electronic product catalogues has primarily focused on resolving semantic conflicts arisen from the heterogeneously designed electronic product catalogues. We argue that while existing integration strategies providing static connections between various heterogeneous catalogues over mediating ontologies, ontologies themselves exhibit heterogeneity and lack of evolvability. What's more, reclassifying terms to link public ontologies is very difficult to avoid inaccuracy problem that is critical to electronic commerce. This paper highlights the problems of flexibility, exactness and evolvability that have received little attention in the literature and provides an overview of the concept exchange approach to interoperability. It illustrates why this is able to better solve the identified problems, presents the different features compared with other approaches and suggests how the concept exchange framework is working.
6234679
A Model-based Approach to Hair Region Segmentation
Hair regions represent an important external feature in many tasks involving the processing of human faces. Currently, the task of locating the hair region in a facial image requires manual intervention. In this paper we examine the different aspects of the hair region segmentation problem and develop an automatic system for such a problem. The system incorporates the human knowledge on where the hair is usually located in a facial image. Segmentation is performed via the classification of image pixels and is based on both textural and geometrical features. Experiments have shown that the segmentation results are generally satisfactory and are at least comparable to the performance of manual extraction.
10065672
The waiting time distribution for a TDMA model with a finite buffer and state-dependent service
We obtain detailed analytic formulas for the density and probability distribution of the waiting time in a time-division multiple-access (TDMA) model with a finite buffer and state-dependent service. On successive intervals of length equal to the duration of a slot, the density is expressed as a linear combination of beta densities with positive coefficients. A recursive scheme, obtained by a matrix-analytic derivation, allows for the highly efficient computations of the coefficient sequences. An expression for the mean waiting time is derived using the classical queueing formula L=/spl lambda/W. We also demonstrate that our methodology provides a concise treatment of various special cases that have been studied over the past half century.
15601163
High Efficiency Digital Halftoning with Two-Element Error Kernel
A high efficiency and good quality error-diffused halftoning is proposed in this paper. An objective halftone image quality evaluation method based on human visual system obtained by least-mean-square is also introduced. The error diffusion algorithm, first introduced by Floyd and Steinberg in 1975, is currently the most popular method of digital halftoning. However, some annoying shortcomings, such as patches of regular textures, worm effect, and computational complexity still need to be improved. Ostromoukhov proposed a three-element error diffusion solving the problems described above, and achieved excellent performance. In this paper, we further reduced the complexity with the proposed two-element error diffusion by cooperating with the proposed LMS-trained quality evaluation. As demonstrated in experiments, the proposed technique further reduced the complexity by 33% compared to Ostromoukhov's method, and it is still comparable in image quality.