323,068 research outputs found
Finding the most vital node of a shortest path
No full textAbstractIn an undirected, 2-node connected graph G=(V,E) with positive real edge lengths, the distance between any two nodes r and s is the length of a shortest path between r and s in G. The removal of a node and its incident edges from G may increase the distance from r to s. A most vital node of a given shortest path from r to s is a node (other than r and s) whose removal from G results in the largest increase of the distance from r to s. In the past, the problem of finding a most vital node of a given shortest path has been studied because of its implications in network management, where it is important to know in advance which component failure will affect network efficiency the most. In this paper, we show that this problem can be solved in O(m+nlogn) time and O(m) space, where m and n denote the number of edges and the number of nodes in G
Computational aspects of a 2-player Stackelberg shortest paths tree game
No full textLet a communication network be modelled by a directed graph G = (V,E) of n nodes and m edges. We consider a one-round two-player network pricing game, the Stackelberg Shortest Paths Tree (StackSPT) game. This is played on G, by assuming that edges in E are partitioned into two sets: a set E F of edges with a fixed positive real weight, and a set E P of edges that should be priced by one of the two players (the leader). Given a distinguished node r ∈ V, the StackSPT game is then as follows: the leader prices the edges in E P in such a way that he will maximize his revenue, knowing that the other player (the follower) will build a shortest paths tree of G rooted at r, say S(r), by running a publicly available algorithm. Quite naturally, for each edge selected in the solution, the leader’s revenue is assumed to be equal to the loaded price of an edge, namely the product of the edge price times the number of paths from r in S(r) that use it. First, we show that the problem of maximizing the leader’s revenue is NP-hard as soon as |E P | = Θ(n). Then, in search of an effective method for solving the problem when the size of E P is constant, we focus on the basic case in which |E P | = 2, and we provide an efficient O(n 2 logn) time algorithm. Afterwards, we generalize the approach to the case |E P | = k, and we show that it can be solved in polynomial time whenever k = O(1)
ENCLOSING MANY BOXES BY AN OPTIMAL PAIR OF BOXES
No full textWe look at the problem: Given a set M of n d-dimensional intervals, find two d-dimensional intervals S, T, such that all intervals in M are enclosed by S or by T, the distribution is balanced and the intervals S and T fulfill a geometric criterion, e.g. like minimum area sum. Up to now no polynomial time algorithm was known for that problem. We present an O(dn log n + d2n2d-1) algorithm for finding an optimal solution
Chemically defined antibody- and small molecule-drug conjugates for in vivo tumor targeting applications: A comparative analysis
No full textWe present the first direct comparative evaluation of an antibody-drug conjugate and of a small molecule-drug conjugate for cancer therapy, using chemically defined products which bind with high-affinity to carbonic anhydrase IX, a marker of tumor hypoxia and of renal cell carcinoma
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Reconstructing visibility graphs with simple robots
No full textWe consider the problem of finding a minimalistic configuration of sensors that enable a simple robot inside an initially unknown polygon P on n vertices to reconstruct the visibility graph of P. The robot can sense features of its environment through its sensors, and it is allowed to move from vertex to vertex. We aim at understanding which sensorial capabilities are sufficient for the reconstruction of the visibility graph of P. We are able to show that the combinatorial visibilities at every vertex do not contain enough information even when combined with the knowledge of the exact interior angle at each vertex. Using sensors that can put distant vertices into a spatial relation on the other hand can in some cases enable our robot to reconstruct the visibility graph of P. We show that this is true for a sensor that can distinguish whether the angle between two vertices the robot sees is convex or reflex, as long as the robot is capable of identifying the vertex it last visited. We also show that measuring angles exactly is enough, if the robot has a compass. © 2010 Springer
Reconstructing visibility graphs with simple robots
No full textWe consider the problem of finding a minimalistic configuration of sensors that enable a simple robot inside an initially unknown polygon P on n vertices to reconstruct the visibility graph of P. The robot can sense features of its environment through its sensors, and it is allowed to move from vertex to vertex. We aim at understanding which sensorial capabilities are sufficient for the reconstruction of the visibility graph of P. We are able to show that the combinatorial visibilities at every vertex do not contain enough information even when combined with the knowledge of the exact interior angle at each vertex. Using sensors that can put distant vertices into a spatial relation on the other hand can in some cases enable our robot to reconstruct the visibility graph of P. We show that this is true for a sensor that can distinguish whether the angle between the lines toward two visible vertices is convex or reflex, as long as the robot is capable of identifying the vertex it last visited. We also show that measuring angles exactly is enough, if the robot has a compass. © 2012 Elsevier B.V. All rights reserved
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