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The latest TensorFlow ActiveQA package comprises three main components along with the code necessary to train and run the ActiveQA agent. First component is a pre-trained sequence to sequence model which takes a question as an input and returns its reformulations. Second component is an answer selection model that uses a convolutional neural network and gives a score to each triplet of the original question, reformulation, and answer. The selector makes use of the pre-trained, and publicly available word embeddings (GloVe). Third component is a question answering system (the environment) that uses BiDAF, a popular question answering system.The TensorFlow package also consists of all the code that is necessary to train and run the ActiveQA agent.
“ActiveQA system.. learns to ask questions that lead to good answers. However, because training data in the form of question pairs, with an original question and a more successful variant, is not readily available, ActiveQA uses reinforcement learning, an approach to machine learning concerned with training agents so that they take actions that maximize a reward, while interacting with an environment”, reads the Google AI blog.
This concept of ActiveQA was first Introduced in Google’s ICLR 2018 paper “Ask the Right Questions: Active Question Reformulation with Reinforcement Learning”. ActiveQA is far different in its approach than the traditional QA systems.Traditional QA systems make use of supervised learning techniques that are used along with labeled data to train a system. This system is capable of answering the arbitrary input questions, however, it doesn’t come with an ability to deal with uncertainty as humans would. For instance, It is not able to reformulate the questions, issue multiple searches, and evaluate the responses. This leads to poor quality answers.
ActiveQA, on the other hand, comprises an agent that consults the QA system repeatedly. This agent reformulates the original question many times which helps it select the best answer. Each of the questions reformulated is evaluated on the basis of how good the corresponding answer to that question is. If the corresponding answer is good, then the learning algorithm adjusts the model’s parameters accordingly. So, the question reformulation that led to the right answer would more likely be generated again. The ActiveQA approach allows the agent to involve in a dynamic interaction with the QA system, which leads to better quality of the returned answers.
As per an example mentioned by Google, if you consider a question “When was Tesla born?”. The agent will reformulate the question in two different ways. One of them being “When is Tesla’s birthday” and the other one as “Which year was Tesla born”. This will help it retrieve the answers to both of the questions from the QA system. Once the systems use all this information, it collectively returns the answer as “July 10, 1856”.
“We envision that this research will help us design systems that provide better and more interpretable answers, and hope it will help others develop systems that can interact with the world using natural language”, mentions Google.
For more information, read the official Google AI blog.