Technical Report MSC-2018-31

Title: Textual Membership Queries
Authors: Jonathan Zarecki
Supervisors: Shaul Markovitch
PDFCurrently accessibly only within the Technion network
Abstract: Human labeling of textual data can be very time-consuming and expensive, yet it is critical for the success of an automatic text classification system. In order to minimize human labeling efforts, we propose a novel active learning (AL) solution, that does not rely on existing sources of unlabeled data. It uses a small amount of labeled data as the core set for the synthesis of useful membership queries (MQs) — unlabeled instances synthesized by an algorithm for human labeling.

Our solution uses modification operators, functions from the instance space to the instance space that change the input to some extent. We apply the operators on the core set, thus creating a set of new membership queries. Using this framework, we look at the instance space as a search space and apply search algorithms in order to create desirable MQs. We implement this framework, along with its modification operators, in the textual domain. The implementation includes using methods such as WordNet and Word2vec, for replacing text fragments from a given sentence with semantically related ones.

We test our framework on several text classification tasks and show improved classifier performance as more MQs are labeled and incorporated into the training set. Furthermore, we show that our MQs can be competitive with a more traditional pool-based active-learning approach, which requires an additional pool of unlabeled instances. To the best of our knowledge, this is the first work on membership queries in the textual domain.

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