China: disidencia y ciberespacio

La reciente condena de Liu Xiaobo, prominente disidente chino, se ha producido en medio de un conflicto de grandes intereses empresariales y políticos, en el marco de un ciberespacio altamente estratégico. Este análisis se propone, primero, explicar la relevancia de la detención de Liu Xiaobo y su importancia en relación con el activismo chino de significado político y social de los últimos años. A continuación ofrece algunas interpretaciones sobre el enfrentamiento Google-Pekín, casi coincidente con el caso Liu y relacionado con ciberataques y censura. Por último, analiza aspectos del pulso de poder en el ciberespacio

Generalization of matching extensions in graphs (II)

Proposed as a general framework, Liu and Yu(Discrete Math. 231 (2001) 311-320) introduced $(n,k,d)$-graphs to unify the concepts of deficiency of matchings, $n$-factor-criticality and $k$-extendability. Let $G$ be a graph and let $n,k$ and $d$ be non-negative integers such that $n+2k+d\leq |V(G)|-2$ and $|V(G)|-n-d$ is even. If when deleting any $n$ vertices from $G$, the remaining subgraph $H$ of $G$ contains a $k$-matching and each such $k$- matching can be extended to a defect-$d$ matching in $H$, then $G$ is called an $(n,k,d)$-graph. In \cite{Liu}, the recursive relations for distinct parameters $n, k$ and $d$ were presented and the impact of adding or deleting an edge also was discussed for the case $d = 0$. In this paper, we continue the study begun in \cite{Liu} and obtain new recursive results for $(n,k,d)$-graphs in the general case $d \geq0$.Comment: 12 page

Parity Reversing Involutions on Plane Trees and 2-Motzkin Paths

The problem of counting plane trees with $n$ edges and an even or an odd number of leaves was studied by Eu, Liu and Yeh, in connection with an identity on coloring nets due to Stanley. This identity was also obtained by Bonin, Shapiro and Simion in their study of Schr\"oder paths, and it was recently derived by Coker using the Lagrange inversion formula. An equivalent problem for partitions was independently studied by Klazar. We present three parity reversing involutions, one for unlabelled plane trees, the other for labelled plane trees and one for 2-Motzkin paths which are in one-to-one correspondence with Dyck paths.Comment: 8 pages, 4 figure

Path integral formulation of Hodge duality on the brane

In the warped compactification with a single Randall-Sundrum brane, a puzzling claim has been made that scalar fields can be bound to the brane but their Hodge dual higher-rank anti-symmetric tensors cannot. By explicitly requiring the Hodge duality, a prescription to resolve this puzzle was recently proposed by Duff and Liu. In this note, we implement the Hodge duality via path integral formulation in the presence of the background gravity fields of warped compactifications. It is shown that the prescription of Duff and Liu can be naturally understood within this framework.Comment: 7 pages, LaTe

Lydia H. Liu. Translingual practice : literature, national culture, and translated modernity : China, 1900-1937

This article reviews the book Translingual Practice: Literature, National Culture, and Translated Modernity—China, 1900-1937 , written by Lydia H. Liu