326,641 research outputs found
Hepatic encephalopathy precipitated by sodium valproate therapy
No full textLetter to the EditorH S Subhash, Robert J Heddle, David W Schultz, John Ring and Campbell H Thompso
Hardness of Bipartite Expansion
No full textWe study the natural problem of estimating the expansion of subsets of vertices on one side of a bipartite graph. More precisely, given a bipartite graph G(U,V,E) and a parameter beta, the goal is to find a subset V' subseteq V containing beta fraction of the vertices of V which minimizes the size of N(V'), the neighborhood of V'. This problem, which we call Bipartite Expansion, is a special case of submodular minimization subject to a cardinality constraint, and is also related to other problems in graph partitioning and expansion. Previous to this work, there was no hardness of approximation known for Bipartite Expansion.
In this paper we show the following strong inapproximability for Bipartite Expansion: for any constants tau, gamma > 0
there is no algorithm which, given a constant beta > 0 and a bipartite graph G(U,V,E), runs in polynomial time and decides whether
- (YES case) There is a subset S^* subseteq V s.t. |S^*| >= beta*|V| satisfying |N(S^*)| <= gamma |U|, or
- (NO case) Any subset S subseteq V s.t. |S| >= tau*beta*|V| satisfies |N(S)| >= (1 - gamma)|U|, unless
NP subseteq intersect_{epsilon > 0}{DTIME}(2^{n^epsi;on}) i.e. NP has subexponential time algorithms.
We note that our hardness result stated above is a vertex expansion analogue of the Small Set (Edge) Expansion Conjecture of
Raghavendra and Steurer 2010
Almost Polynomial Factor Inapproximability for Parameterized k-Clique
No full textThe k-Clique problem is a canonical hard problem in parameterized complexity.
In this paper, we study the parameterized complexity of approximating the
k-Clique problem where an integer k and a graph G on n vertices are given as
input, and the goal is to find a clique of size at least k/F(k) whenever the
graph G has a clique of size k. When such an algorithm runs in time T(k)poly(n)
(i.e., FPT-time) for some computable function T, it is said to be an
F(k)-FPT-approximation algorithm for the k-Clique problem.
Although, the non-existence of an F(k)-FPT-approximation algorithm for any
computable sublinear function F is known under gap-ETH [Chalermsook et al.,
FOCS 2017], it has remained a long standing open problem to prove the same
inapproximability result under the more standard and weaker assumption,
W[1]FPT.
In a recent breakthrough, Lin [STOC 2021] ruled out constant factor (i.e.,
F(k)=O(1)) FPT-approximation algorithms under W[1]FPT. In this paper, we
improve this inapproximability result (under the same assumption) to rule out
every factor FPT-approximation algorithm for any increasing
computable function H (for example ).
Our main technical contribution is introducing list decoding of Hadamard
codes over large prime fields into the proof framework of Lin
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)
Synthesis, characterization and liquefied petroleum gas (LPG) sensing properties of WO3 nano-particles
No full textGoing 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
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