1876314
A 2-Approximation Algorithm for Path Coloring on Trees of Rings
A tree of rings is an undirected graph obtained from a tree by replacing each node of the tree with a cycle and then contracting the edges of the tree so that two cycles corresponding to the two end-nodes of any edge have precisely one node in common. Given a set of paths on a tree of rings, the routing problem is to color the paths with the smallest number of colors so that any two paths sharing an edge are assigned different colors. We present a 2-approximation algorithm in this paper.
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.
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.
7451094
Orthogonal (g, f)-factorizations in networks
Let G = (V,E) be a graph and let g and f be two integer-valued functions defined on V such that k ≤ g(x) ≤ f(x) for all x ∈ V . Let H1,H2, · · · ,Hk be subgraphs of G such that |E(Hi)| = m, 1 ≤ i ≤ k, and V (Hi) ∩ V (Hj) = ∅ when i 6= j. In this paper it is proved that every (mg + m − 1,mf −m + 1)-graph G has a (g, f)-factorization orthogonal to Hi for i = 1, 2, · · · , k and shown that there are polynomial-time algorithms to find the desired (g, f)-factorizations.
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.
9766004
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 nonpreemptively. 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 due to D. S. Hochbaum and D. Landy [6]. In this paper, we establish the first polynomial time approximation scheme (PTAS) for the problem.
2186483
Improvements for the Symbolic Verification of Timed Automata
Based on the equivalence relation for location based reachability between continuous and integer semantics of closed timed automata, Beyer et al. have implemented the verifier Rabbit, with the uniform representation of reachable configurations. However, the growth of maximal constant of clock variables will decline the performance of Rabbit. The paper proposes an improved symbolic method, using binary decision diagrams (BDDs) to store the symbolic representation of discretized states, for the verification of timed systems. Compared with Rabbit, experiments demonstrate that besides the memory reduction, our implementation is also less sensitive to the size of clock domain.
920610
Interactive visualization of three-dimensional vector fields with flexible appearance control
We present an interactive texture-based algorithm for visualizing three-dimensional steady and unsteady 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, flow lines are generated from the 3D vector data. Various geometric properties of the flow paths 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 vector field. Our algorithm allows the user to interactively navigate through different regions of interest in the underlying field and experiment with various appearance textures. 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.
14226296
Translation initiation sites prediction with mixture Gaussian models in human cDNA sequences
Translation initiation sites (TISs) are important signals in cDNA sequences. Many research efforts have tried to predict TISs in cDNA sequences. In this paper, we propose to use mixture Gaussian models for TIS prediction. Using both local features and some features generated from global measures, the proposed method predicts TISs with a sensitivity of 98 percent and a specificity of 93.6 percent. Our method outperforms many other existing methods in sensitivity while keeping specificity high. We attribute the improvement in sensitivity to the nature of the global features and the mixture Gaussian models.
1032115
Incremental Mining of Frequent Query Patterns from XML Queries for Caching
Existing studies for mining frequent XML query patterns mainly introduce a straightforward candidate generate-and-test strategy and compute frequencies of candidate query patterns from scratch periodically by checking the entire transaction database, which consists of XML query patterns transformed from user queries. However, it is nontrivial to maintain such discovered frequent patterns in real XML databases because there may incur frequent updates that may not only invalidate some existing frequent query patterns but also generate some new frequent ones. Accordingly, existing proposals are inefficient for the evolution of the transaction database. To address these problems, this paper presents an efficient algorithm IPS-FXQPMiner for mining frequent XML query patterns without candidate maintenance and costly tree-containment checking. We transform XML queries into sequences through a one- to-one mapping and then mine the frequent sequences to generate frequent XML query patterns. More importantly, based on IPS-FXQPMiner, an efficient incremental algorithm, Incre-FXQPMiner is proposed to incrementally mine frequent XML query patterns, which can minimize the I/O and computation requirements for handling incremental updates. Our experimental study on various real-life datasets demonstrates the efficiency and scalability of our algorithms over previous known alternatives.
44653881
DMT: A Flexible and Versatile Selectivity Estimation Approach for Graph Query
Efficient and accurate selectivity estimation in graph-structured data, specifically for complex branching path query, is becoming a challenging and all-important problem for query performance optimization. Precise and flexible statistics summarization about graph-structured data plays a crucial role for graph query selectivity estimation. We propose DMT, Dynamic Markov Table, which is a dynamic graph summarization based on Markov Table by applying flexible combination of 4 Optimized Rules which investigate local forward and backward inclusions. The efficient DMT construction algorithm DMTBuilder and DMT-based statistical methods are introduced for selectivity estimations of various graph queries. Our extensive experiments demonstrate the advantages in accuracy and scalability of DMT by comparing with previously known alternative, as well as the preferred Optimized Rules that would favor different situations.