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.
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.
14019711
Fixed-parameter tractability and data reduction for multicut in trees
We study an NP-complete (and MaxSNP-hard) communication problem on tree networks, the so-called Multicut in Trees: given an undirected tree and some pairs of nodes of the tree, find out whether there is a set of at most k tree edges whose removal separates all given pairs of nodes. Multicut has been intensively studied for trees as well as for general graphs mainly from the viewpoint of polynomialtime approximation algorithms. By way of contrast, we provide a simple fixed-parameter algorithm for Multicut in Trees showing ∗Supported by the Deutsche Forschungsgemeinschaft (DFG), Emmy Noether research group PIAF (fixed-parameter algorithms), NI 369/4. Parts of this work have been done while the authors were at the Universität Tübingen.
16182314
Improved Fixed-Parameter Algorithms for Two Feedback Set Problems
Settling a ten years open question, we show that the NP-complete Feedback Vertex Set problem is deterministically solvable in O(ck · m) time, where m denotes the number of graph edges, k denotes the size of the feedback vertex set searched for, and c is a constant. As a second result, we present a fixed-parameter algorithm for the NP-complete Edge Bipartization problem with runtime O(2k · m2).
10753870
Error Compensation in Leaf Root Problems
The k-Leaf Root problem is a particular case of graph power problems Here, we study “error correction” versions of k-Leaf Root—that is, for instance, adding or deleting at most l edges to generate a graph that has a k-leaf root We provide several NP-completeness results in this context, and we show that the NP-complete Closest 3-Leaf Root problem (the error correction version of 3-Leaf Root) is fixed-parameter tractable with respect to the number of edge modifications in the given graph Thus, we provide the seemingly first nontrivial positive algorithmic results in the field of error compensation for leaf root problems with k > 2 To this end, as a result of independent interest, we develop a forbidden subgraph characterization of graphs with 3-leaf roots.
10069776
Automated Generation of Search Tree Algorithms for Hard Graph
Modification Problems
Abstract
We present a framework for an automated 
generation of exact search tree algorithms for NP-hard problems.
The purpose of our approach is twofold—rapid development and 
improved upper bounds. 
Many search tree algorithms for various problems
in the literature are based on complicated
case distinctions. Our approach may lead to a much 
simpler process of developing and analyzing these algorithms.
Moreover, using the sheer computing power of machines it may also 
lead to improved upper bounds on
search tree sizes (i.e., faster exact solving algorithms) in comparison
with previously developed “hand-made” search trees.
Among others, such an example is given with the NP-complete 
Cluster Editing problem (also known as Correlation
Clustering on complete unweighted graphs), which asks for the minimum
number of edge additions and deletions to create a graph which is a
disjoint union of cliques. The
hand-made search tree
for Cluster Editing
had worst-case size O(2.27k), which now is improved to 
O(1.92k) due to our new method.
(Herein, k denotes the number of edge modifications allowed.)


30330476
Measurement Models for Survivability and Competitiveness of Very Large E-marketplace
E-Marketplace is a man-made profit center with emergent customer requirements. This emergence nature poses many difficulties for e-marketplace to satisfy its customers and thus affects its survivability and competitiveness. To challenge this issue, this paper has introduced a novel emergent emarketplace model, and analyzed and quantified the emergent properties of emarketplace from simple ESMs to very large complex electronic intermediary EIMs. The measurement models developed in this paper are very useful for producing dynamic interaction records appropriate for further simulation model of e-marketplaces.
41178770
On matching coefficients
Abstract Explicit formulae are derived for the first four coefficients of the matching polynomial of a graph in terms of properties of the graph. An explicit formula is also derived for the number of triangles in the complement of a graph in terms of the parameters of the graph. Also, some extremal properties of regular multipartite graphs are identified.
43856313
The waiting time distribution for a TDMA model with a finite buffer
Detailed analytic formulas for the density and probability distribution of the waiting time in a TDMA model with a finite buffer is obtained. On successive intervals of length equal to the duration of a slot, the density is expressed as (infinite) linear combinations 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.
17686470
Inter-enterprise business document exchange
Electronic business document interoperation is the cornerstone of business process integration. An essential issue for business document interoperation is to maintain semantic consistency of the exchanged business documents between any two autonomous business communities, where the document sender and receiver have no misunderstanding in using the exchanged documents. Existing approaches to resolving this issue either adopts document standards to map heterogeneous document elements or applies business ontologies to mediate inconsistent document elements. While these approaches are effective in certain degree, the issues of limited flexibility and evolvability in using standards and the lack of accuracy in using ontologies to mediate document elements must be explored and resolved. This paper proposes a Collaborative Document Exchange (CODEX) approach to resolving the issues. In this approach, structures and concepts of business document are separated and layered in CODEX framework. Structures provide the commonality of business documents through classified concept identifiers while concepts support particularity of business documents through collaboration.
6950256
Context representation, transformation and comparison for ad hoc product data exchange
Product data exchange is the precondition of business interoperation between Web-based firms. However, millions of small and medium sized enterprises (SMEs) encode their Web product data in ad hoc formats for electronic product catalogues. This prevents product data exchange between business partners for business interoperation. To solve this problem, this paper has proposed a novel concept-centric catalogue engineering approach for representing, transforming and comparing semantic contexts in ad hoc product data exchange. In this approach, concepts and contexts of product data are specified along data exchange chain and are mapped onto several novel XML product map (XPM) documents by utilizing XML hierarchical structure and its syntax. The designed XPM has overcome the semantic limitations of XML markup and has achieved the semantic interoperation for ad hoc product data exchange.