2,351 research outputs found
A Survey of Word Reordering in Statistical Machine Translation: Computational Models and Language Phenomena
Word reordering is one of the most difficult aspects of statistical machine
translation (SMT), and an important factor of its quality and efficiency.
Despite the vast amount of research published to date, the interest of the
community in this problem has not decreased, and no single method appears to be
strongly dominant across language pairs. Instead, the choice of the optimal
approach for a new translation task still seems to be mostly driven by
empirical trials. To orientate the reader in this vast and complex research
area, we present a comprehensive survey of word reordering viewed as a
statistical modeling challenge and as a natural language phenomenon. The survey
describes in detail how word reordering is modeled within different
string-based and tree-based SMT frameworks and as a stand-alone task, including
systematic overviews of the literature in advanced reordering modeling. We then
question why some approaches are more successful than others in different
language pairs. We argue that, besides measuring the amount of reordering, it
is important to understand which kinds of reordering occur in a given language
pair. To this end, we conduct a qualitative analysis of word reordering
phenomena in a diverse sample of language pairs, based on a large collection of
linguistic knowledge. Empirical results in the SMT literature are shown to
support the hypothesis that a few linguistic facts can be very useful to
anticipate the reordering characteristics of a language pair and to select the
SMT framework that best suits them.Comment: 44 pages, to appear in Computational Linguistic
The Dumont Ansatz for the Eulerian Polynomials, Peak Polynomials and Derivative Polynomials
We observe that three context-free grammars of Dumont can be brought to a
common ground, via the idea of transformations of grammars, proposed by
Ma-Ma-Yeh. Then we develop a unified perspective to investigate several
combinatorial objects in connection with the bivariate Eulerian polynomials. We
call this approach the Dumont ansatz.
As applications, we provide grammatical treatments, in the spirit of the
symbolic method, of relations on the Springer numbers, the Euler numbers, the
three kinds of peak polynomials, an identity of Petersen, and the two kinds of
derivative polynomials, introduced by Knuth-Buckholtz and Carlitz-Scoville, and
later by Hoffman in a broader context. We obtain a convolution formula on the
left peak polynomials, leading to the Gessel formula. In this framework, we are
led to the combinatorial interpretations of the derivative polynomials due to
Josuat-Verg\`es.Comment: 30 pages, 5 figure
- …