scholarly journals New decidable upper bound of the second level in the Straubing-Therien concatenation hierarchy of star-free languages

2010 ◽  
Vol Vol. 12 no. 4 ◽  
Author(s):  
Jorge Almeida ◽  
Ondrej Klima

special issue dedicated to the second edition of the conference AutoMathA: from Mathematics to Applications International audience In a recent paper we gave a counterexample to a longstanding conjecture concerning the characterization of regular languages of level 2 in the Straubing-Therien concatenation hierarchy of star-free languages. In that paper a new upper bound for the corresponding pseudovariety of monoids was implicitly given. In this paper we show that it is decidable whether a given monoid belongs to the new upper bound. We also prove that this new upper bound is incomparable with the previous upper bound.

2012 ◽  
Vol Vol. 13 no. 4 ◽  
Author(s):  
Robert F. Bailey ◽  
Karen Meagher

special issue in honor of Laci Babai's 60th birthday: Combinatorics, Groups, Algorithms, and Complexity International audience The metric dimension of a graph Gamma is the least number of vertices in a set with the property that the list of distances from any vertex to those in the set uniquely identifies that vertex. We consider the Grassmann graph G(q)(n, k) (whose vertices are the k-subspaces of F-q(n), and are adjacent if they intersect in a (k 1)-subspace) for k \textgreater= 2. We find an upper bound on its metric dimension, which is equal to the number of 1-dimensional subspaces of F-q(n). We also give a construction of a resolving set of this size in the case where k + 1 divides n, and a related construction in other cases.


2014 ◽  
Vol Vol. 16 no. 2 (PRIMA 2013) ◽  
Author(s):  
Xuegang Chen ◽  
Jing Huang

Special issue PRIMA 2013 International audience As a common generalization of bipartite and split graphs, monopolar graphs are defined in terms of the existence of certain vertex partitions. It has been shown that to determine whether a graph has such a partition is NP-complete for general graphs and polynomial for several classes of graphs. In this paper, we investigate graphs that admit a unique such partition and call them uniquely monopolar-partitionable graphs. By employing a tree trimming technique, we obtain a characterization of uniquely monopolar-partitionable block graphs. Our characterization implies a polynomial time algorithm for recognizing them.


2014 ◽  
Vol Vol. 16 no. 2 (PRIMA 2013) ◽  
Author(s):  
Igor Ramos ◽  
Vinícius F. Santos ◽  
Jayme L. Szwarcfiter

Special issue PRIMA 2013 International audience We consider the P₃-convexity on simple undirected graphs, in which a set of vertices S is convex if no vertex outside S has two or more neighbors in S. The convex hull H(S) of a set S is the smallest convex set containing S as a subset. A set S is a convexly independent set if v \not ∈ H(S\setminus \v\) for all v in S. The rank \rk(G) of a graph is the size of the largest convexly independent set. In this paper we consider the complexity of determining \rk(G). We show that the problem is NP-complete even for split or bipartite graphs with small diameter. We also show how to determine \rk(G) in polynomial time for the well structured classes of graphs of trees and threshold graphs. Finally, we give a tight upper bound for \rk(G), which in turn gives a tight upper bound for the Radon number as byproduct, which is the same obtained before by Henning, Rautenbach and Schäfer. Additionally, we briefly show that the problem is NP-complete also in the monophonic convexity.


Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 237
Author(s):  
Carolina Cardell ◽  
Jose Santiago Pozo-Antonio

The physical–chemical characterization of natural and synthetic historical inorganic and mineral pigments, which may be found embedded in paintings (real or mock-ups), glass, enamel, ceramics, beads, tesserae, etc., as well as their alteration under different decay scenarios, is a demanding line of investigation. This field of research is now both well established and dynamic, as revealed by the numerous publications in high-quality journals of varied scientific disciplines. [...]


2021 ◽  
Vol 7 (6) ◽  
pp. 89
Author(s):  
Valerio De Santis

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...]


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adrian Creanga ◽  
Rebecca A. Gillespie ◽  
Brian E. Fisher ◽  
Sarah F. Andrews ◽  
Julia Lederhofer ◽  
...  

AbstractBroadly neutralizing antibodies (bnAbs) have been developed as potential countermeasures for seasonal and pandemic influenza. Deep characterization of these bnAbs and polyclonal sera provides pivotal understanding for influenza immunity and informs effective vaccine design. However, conventional virus neutralization assays require high-containment laboratories and are difficult to standardize and roboticize. Here, we build a panel of engineered influenza viruses carrying a reporter gene to replace an essential viral gene, and develop an assay using the panel for in-depth profiling of neutralizing antibodies. Replication of these viruses is restricted to cells expressing the missing viral gene, allowing it to be manipulated in a biosafety level 2 environment. We generate the neutralization profile of 24 bnAbs using a 55-virus panel encompassing the near-complete diversity of human H1N1 and H3N2, as well as pandemic subtype viruses. Our system offers in-depth profiling of influenza immunity, including the antibodies against the hemagglutinin stem, a major target of universal influenza vaccines.


2010 ◽  
Vol 76 (764) ◽  
pp. 383-385 ◽  
Author(s):  
Taiju SHIBATA ◽  
Junya SUMITA ◽  
Taiyo MAKITA ◽  
Takashi TAKAGI ◽  
Eiji KUNIMOTO ◽  
...  

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