Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evaluating Multilingual Text Encoders for Unsupervised Cross-Lingual
  Retrieval   Pretrained multilingual text encoders based on neural Transformer
architectures, such as multilingual BERT (mBERT) and XLM, have achieved strong
performance on a myriad of language understanding tasks. Consequently, they
have been adopted as a go-to paradigm for multilingual and cross-lingual
representation learning and transfer, rendering cross-lingual word embeddings
(CLWEs) effectively obsolete. However, questions remain to which extent this
finding generalizes 1) to unsupervised settings and 2) for ad-hoc cross-lingual
IR (CLIR) tasks. Therefore, in this work we present a systematic empirical
study focused on the suitability of the state-of-the-art multilingual encoders
for cross-lingual document and sentence retrieval tasks across a large number
of language pairs. In contrast to supervised language understanding, our
results indicate that for unsupervised document-level CLIR -- a setup with no
relevance judgments for IR-specific fine-tuning -- pretrained encoders fail to
significantly outperform models based on CLWEs. For sentence-level CLIR, we
demonstrate that state-of-the-art performance can be achieved. However, the
peak performance is not met using the general-purpose multilingual text
encoders `off-the-shelf', but rather relying on their variants that have been
further specialized for sentence understanding tasks.

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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn