37978882
Hamiltonian cycles in 3-connected Claw-free graphs
It is shown that every 3-connected claw-free graph having at most 6δ - 7 vertices is hamiltonian, where δ is the minimum degree.
40174055
A PTAS for Distinguishing (Sub)string Selection
Consider two sets of strings, B (bad genes) and G (good genes), as well as two integers db and dg (db ? dg). A frequently occurring problem in computational biology (andother fields) is to finda (distinguishing) substring s of length L that distinguishes the bad strings from goodstrings, i.e., for each string si ? B there exists a length-L substring ti of si with d(s, ti) ? db (close to badstrings) andfor every substring ui of length L of every string gi ? G, d(s, ui) ? dg (far from goodstrings). We present a polynomial time approximation scheme to settle the problem, i.e., for any constant ? > 0, the algorithm finds a string s of length L such that for every si ? B, there is a length-L substring ti of si with d(ti, s) ? (1+?)db and for every substring ui of length L of every gi ? G, d(ui, s) ? (1 - ?)dg, if a solution to the original pair (db ? dg) exists.
29830975
A PTAS for Minimizing Total Completion Time of Bounded Batch Scheduling
We consider a batch processing system {pi : i = 1, 2,…,n} where pi is the processing time of job i, and up to B jobs can be processed together such that the handling time of a batch is the longest processing time among jobs in the batch. The number of job types m is not fixed and all the jobs are released at the same time. Jobs are executed non-preemptively. Our objective is to assign jobs to batches and sequence the batches so as to minimize the total completion time. The best previously known result is a 2–approximation algorithm. In this paper, we establish the first polynomial time approximation scheme (PTAS) for the problem.
9386148
Orthogonal factorizations of graphs
Let G be a graph with vertex set V(G) and edge set E(G), and let g and f be two nonnegative integer-valued functions defined on V(G) such that g(x) ≤ f(x) for every vertex x of V(G). We use dG(x) to denote the degree of a vertex x of G. A graph G is called a (g,f)-graph if g(x) ≤ dG(x) ≤ f(x) for each x ∈ V(G). Then a spanning subgraph F of G is said to be a (g,f)-factor of G if F itself is a (g,f)-graph. A (g,f)-factorization of G is a partition of E(G) into edge disjoint (g,f)-factors. Let F = {F1,F2,... ,Fm} be a factorization of G and H be a subgraph of G with m edges. If Fi, 1 ≤ i ≤ m, has exactly one edge in common with H, we say that F is orthogonal to H. In this paper it is proved that every (mg + k,mf - k)-graph contains a subgraph R such that R has a (g,f)-factorization orthogonal to a given subgraph with k edges, where m and k are positive integers with 1 ≤ k > m and g(x) ≥ 0. This result has been conjectured by Yan in Yan (Sci. China Ser. A 41(1) (1998) 48).
7761968
A PTAS for Semiconductor Burn-in Scheduling
In this paper a polynomial time approximation scheme, PTAS for short, is presented for the problem of scheduling jobs in a batch processing system. Each job has a pre-defined release date, which indicates when the job is available, and a pre-defined burn-in time, which is the least time needed for processing the job. At one time, at most B jobs can be processed together, where B is a pre-given number. No preemption is permitted.
11626813
Sorting Signed Permutations by Fixed-length Reversals
A signed n-permutation is a permutation on {1,2,…,n} in which each element is labelled by a positive or negative sign. Here we consider the problem of sorting signed permutations by fixed-length reversals. Indeed, limiting the transformations to reversals of length exactly k can be very restrictive, for example, (+1,+3,+2,+4,…,+n) can never be sorted to (+1,+2,+3,+4,…,+n) by 2-reversals. That is, for given two signed permutations it is not obvious whether they can be sorted to each other by k-reversals. Thus in 1996, Chen and Skiena gave the following open problem: what is the connectedness of signed permutations under fixed-length reversals? In this paper, we resolve this open problem when "fixed-length" is even, and give a characterization of the connectedness of signed n-permutations under 2l-reversal, for both linear and circular permutations.
664043
Evolutionary structure learning algorithm for Bayesian network and Penalized Mutual Information metric
The paper formulates the problem of learning Bayesian network structures from data as determining the structure that best approximates the probability distribution indicated by the data. A new metric, Penalized Mutual Information metric, is proposed, and an evolutionary algorithm is designed to search for the best structure among alternatives. The experimental results show that this approach is reliable and promising.
8467998
Truncation for Low-Complexity MIMO Signal Detection
Joint maximum-likelihood (JML) detector may be used in memoryless multiple-input multiple-output (MIMO) systems to obtain optimal detection performance. However, JML detector performs an exhaustive search and has prohibitively large decoding complexity. To reduce the complexity of MIMO signal detection, minimum mean-square-error (mmse) linear detector (LD), decision-feedback detector (DFD), group detector, and sphere detector (SD) may be used. In this correspondence, we propose a truncation based detector for low-complexity MIMO signal detection, and give theoretical insight into the design and performance of such a detector. We study bitruncation in detail and present two bitruncation approaches. These approaches have low-complexity, and computer simulation results show that they outperform mmse-LD and mmse-DFD
46516744
Efficient Keyword Search over Data-Centric XML Documents
We in this paper investigate keyword search over data-centric XML documents. We first present a novel method to divide an XML document into self-integrated subtrees, which are connected subtrees and can capture different structural information of the XML document. We then propose the meaningful self-integrated trees, which contain all the keywords and describe how the keywords are interrelated, to answer keyword search over XML documents. In addition, we introduce the B+-tree index to accelerate the retrieval of those meaningful self-integrated trees. Moreover, to further enhance the performance of keyword search, we present Bloom Filter to improve the efficiency of generating those meaningful self-integrated trees. Finally, we conducted extensive experiments to evaluate the performance of our method, and the experimental results demonstrate that our method achieves high efficiency and outperforms the existing approaches significantly.
537628
Chameleon: an interactive texture-based rendering framework for visualizing three-dimensional vector fields
In this paper we present an interactive texture-based technique for visualizing three-dimensional vector fields. The goal of the algorithm is to provide a general volume rendering framework allowing the user to compute three-dimensional flow textures interactively, and to modify the appearance of the visualization on the fly. To achieve our goal, we decouple the visualization pipeline into two disjoint stages. First, streamlines are generated from the 3D vector data. Various geometric properties of the streamlines are extracted and converted into a volumetric form using a hardware-assisted slice sweeping algorithm. In the second phase of the algorithm, the attributes stored in the volume are used as texture coordinates to look up an appearance texture to generate both informative and aesthetic representations of the underlying vector field. Users can change the input textures and instantaneously visualize the rendering results. With our algorithm, visualizations with enhanced structural perception using various visual cues can be rendered in real time. A myriad of existing geometry-based and texture-based visualization techniques can also be emulated.
10744767
Typing Aberrance in Signal Transduction
We have developed a calculus, called Ipi, for describing the aberrance in biological models. Our approach extends the traditional pi calculus to handle aberrant process in the signal transduction. In this paper we propose a typing system that replaces the tag system of Ipi calculus. It is shown that the typing system is equal to the tag system in terms of the expressive power.