2,240 research outputs found
On Unconstrained Quasi-Submodular Function Optimization
With the extensive application of submodularity, its generalizations are
constantly being proposed. However, most of them are tailored for special
problems. In this paper, we focus on quasi-submodularity, a universal
generalization, which satisfies weaker properties than submodularity but still
enjoys favorable performance in optimization. Similar to the diminishing return
property of submodularity, we first define a corresponding property called the
{\em single sub-crossing}, then we propose two algorithms for unconstrained
quasi-submodular function minimization and maximization, respectively. The
proposed algorithms return the reduced lattices in iterations,
and guarantee the objective function values are strictly monotonically
increased or decreased after each iteration. Moreover, any local and global
optima are definitely contained in the reduced lattices. Experimental results
verify the effectiveness and efficiency of the proposed algorithms on lattice
reduction.Comment: 11 page
Structural Stability of Lexical Semantic Spaces: Nouns in Chinese and French
Many studies in the neurosciences have dealt with the semantic processing of
words or categories, but few have looked into the semantic organization of the
lexicon thought as a system. The present study was designed to try to move
towards this goal, using both electrophysiological and corpus-based data, and
to compare two languages from different families: French and Mandarin Chinese.
We conducted an EEG-based semantic-decision experiment using 240 words from
eight categories (clothing, parts of a house, tools, vehicles,
fruits/vegetables, animals, body parts, and people) as the material. A
data-analysis method (correspondence analysis) commonly used in computational
linguistics was applied to the electrophysiological signals.
The present cross-language comparison indicated stability for the following
aspects of the languages' lexical semantic organizations: (1) the
living/nonliving distinction, which showed up as a main factor for both
languages; (2) greater dispersion of the living categories as compared to the
nonliving ones; (3) prototypicality of the \emph{animals} category within the
living categories, and with respect to the living/nonliving distinction; and
(4) the existence of a person-centered reference gradient. Our
electrophysiological analysis indicated stability of the networks at play in
each of these processes. Stability was also observed in the data taken from
word usage in the languages (synonyms and associated words obtained from
textual corpora).Comment: 17 pages, 4 figure
Extracting Keyphrases from Chinese News Articles Using TextRank and Query Log Knowledge
PACLIC 23 / City University of Hong Kong / 3-5 December 200
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