821,771 research outputs found
Limitations of Cross-Lingual Learning from Image Search
Cross-lingual representation learning is an important step in making NLP
scale to all the world's languages. Recent work on bilingual lexicon induction
suggests that it is possible to learn cross-lingual representations of words
based on similarities between images associated with these words. However, that
work focused on the translation of selected nouns only. In our work, we
investigate whether the meaning of other parts-of-speech, in particular
adjectives and verbs, can be learned in the same way. We also experiment with
combining the representations learned from visual data with embeddings learned
from textual data. Our experiments across five language pairs indicate that
previous work does not scale to the problem of learning cross-lingual
representations beyond simple nouns
SL(2,R)/U(1) Supercoset and Elliptic Genera of Non-compact Calabi-Yau Manifolds
We first discuss the relationship between the SL(2;R)/U(1) supercoset and N=2
Liouville theory and make a precise correspondence between their
representations. We shall show that the discrete unitary representations of
SL(2;R)/U(1) theory correspond exactly to those massless representations of N=2
Liouville theory which are closed under modular transformations and studied in
our previous work hep-th/0311141.
It is known that toroidal partition functions of SL(2;R)/U(1) theory (2D
Black Hole) contain two parts, continuous and discrete representations. The
contribution of continuous representations is proportional to the space-time
volume and is divergent in the infinite-volume limit while the part of discrete
representations is volume-independent.
In order to see clearly the contribution of discrete representations we
consider elliptic genus which projects out the contributions of continuous
representations: making use of the SL(2;R)/U(1), we compute elliptic genera for
various non-compact space-times such as the conifold, ALE spaces, Calabi-Yau
3-folds with A_n singularities etc. We find that these elliptic genera in
general have a complex modular property and are not Jacobi forms as opposed to
the cases of compact Calabi-Yau manifolds.Comment: 39 pages, no figure; v2 references added, minor corrections; v3 typos
corrected, to appear in JHEP; v4 typos corrected in eqs. (3.22) and (3.44
The Latent Relation Mapping Engine: Algorithm and Experiments
Many AI researchers and cognitive scientists have argued that analogy is the
core of cognition. The most influential work on computational modeling of
analogy-making is Structure Mapping Theory (SMT) and its implementation in the
Structure Mapping Engine (SME). A limitation of SME is the requirement for
complex hand-coded representations. We introduce the Latent Relation Mapping
Engine (LRME), which combines ideas from SME and Latent Relational Analysis
(LRA) in order to remove the requirement for hand-coded representations. LRME
builds analogical mappings between lists of words, using a large corpus of raw
text to automatically discover the semantic relations among the words. We
evaluate LRME on a set of twenty analogical mapping problems, ten based on
scientific analogies and ten based on common metaphors. LRME achieves
human-level performance on the twenty problems. We compare LRME with a variety
of alternative approaches and find that they are not able to reach the same
level of performance.Comment: related work available at http://purl.org/peter.turney
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