Edouard Grave

Weakly-Supervised Alignment of Video with Text

Suppose that we are given a set of videos, along with natural language descriptions in the form of multiple sentences (e.g., manual annotations, movie scripts, sport summaries etc.), and that these sentences appear in the same temporal order as their visual counterparts. We propose in this paper a method for aligning the two modalities, i.e., automatically providing a time (frame) stamp for every sentence. Given vectorial features for both video and text, this can be cast as a temporal assignment problem, with an implicit linear mapping between the two feature modalities. We formulate this problem as an integer quadratic program, and solve its continuous convex relaxation using an efficient conditional gradient algorithm. Several rounding procedures are proposed to construct the final integer solution. After demonstrating significant improvements over the state of the art on the related task of aligning video with symbolic labels [7], we evaluate our method on a challenging dataset of videos with associated textual descriptions [37], and explore bag-of-words and continuous representations for text.

A convex relaxation for weakly supervised relation extraction

A promising approach to relation extraction, called weak or distant supervision, exploits an existing database of facts as training data, by aligning it to an unlabeled collection of text documents. Using this approach, the task of relation extraction can easily be scaled to hundreds of different relationships. However, distant supervision leads to a challenging multiple instance, multiple label learning problem. Most of the proposed solutions to this problem are based on non-convex formulations, and are thus prone to local minima. In this article, we propose a new approach to the problem of weakly supervised relation extraction, based on discriminative clustering and leading to a convex formulation. We demonstrate that our approach outperforms state-of-the-art methods on the challenging dataset introduced by Riedel et al. (2012).