Weakly-supervised action localization aims to recognize and localize action
instancese in untrimmed videos with only video-level labels. Most existing
models rely on multiple instance learning(MIL), where the predictions of
unlabeled instances are supervised by classifying labeled bags. The MIL-based
methods are relatively well studied with cogent performance achieved on
classification but not on localization. Generally, they locate temporal regions
by the video-level classification but overlook the temporal variations of
feature semantics. To address this problem, we propose a novel attention-based
hierarchically-structured latent model to learn the temporal variations of
feature semantics. Specifically, our model entails two components, the first is
an unsupervised change-points detection module that detects change-points by
learning the latent representations of video features in a temporal hierarchy
based on their rates of change, and the second is an attention-based
classification model that selects the change-points of the foreground as the
boundaries. To evaluate the effectiveness of our model, we conduct extensive
experiments on two benchmark datasets, THUMOS-14 and ActivityNet-v1.3. The
experiments show that our method outperforms current state-of-the-art methods,
and even achieves comparable performance with fully-supervised methods.

本文提出了一种基于注意力机制的分层结构潜在模型，用于学习特征语义的时间变化，通过两个组件进行实现：第一个是无监督的变点检测模块，通过在时间层次中学习视频特征的变化率来检测变点；第二个是基于注意力的分类模型，将前景的变点作为边界来选择。通过在两个基准数据集 THUMOS-14 和 ActivityNet-v1.3 上进行广泛实验，结果表明我们的方法优于当前最先进的方法，并且甚至与全监督方法具有可比较的性能。

层次结构潜在注意力建模的弱监督动作定位

Weakly-Supervised Action Localization by Hierarchically-structured  Latent Attention Modeling

We present the group fused Lasso for detection of multiple change-points
shared by a set of co-occurring one-dimensional signals. Change-points are
detected by approximating the original signals with a constraint on the
multidimensional total variation, leading to piecewise-constant approximations.
Fast algorithms are proposed to solve the resulting optimization problems,
either exactly or approximately. Conditions are given for consistency of both
algorithms as the number of signals increases, and empirical evidence is
provided to support the results on simulated and array comparative genomic
hybridization data.

通过约束多维总变化的方法，我们提出了一种基于组合融合拉索的方法来探测一组共同出现的一维信号上的变化点，并提出了快速算法来解决相关的优化问题。我们给出了几个解决方案的条件，以确保算法在信号数量增加时保持一致性，并通过对模拟数据和基因组杂交数据的实证证据来支持这些结果。