Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reinforcement Learning for Weakly Supervised Temporal Grounding of
  Natural Language in Untrimmed Videos   Temporal grounding of natural language in untrimmed videos is a fundamental
yet challenging multimedia task facilitating cross-media visual content
retrieval. We focus on the weakly supervised setting of this task that merely
accesses to coarse video-level language description annotation without temporal
boundary, which is more consistent with reality as such weak labels are more
readily available in practice. In this paper, we propose a \emph{Boundary
Adaptive Refinement} (BAR) framework that resorts to reinforcement learning
(RL) to guide the process of progressively refining the temporal boundary. To
the best of our knowledge, we offer the first attempt to extend RL to temporal
localization task with weak supervision. As it is non-trivial to obtain a
straightforward reward function in the absence of pairwise granular
boundary-query annotations, a cross-modal alignment evaluator is crafted to
measure the alignment degree of segment-query pair to provide tailor-designed
rewards. This refinement scheme completely abandons traditional sliding window
based solution pattern and contributes to acquiring more efficient,
boundary-flexible and content-aware grounding results. Extensive experiments on
two public benchmarks Charades-STA and ActivityNet demonstrate that BAR
outperforms the state-of-the-art weakly-supervised method and even beats some
competitive fully-supervised ones.

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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th