Manhattan Siamese LSTM for Question Retrieval in Community Question Answering

Community Question Answering (cQA) are platforms where users can post their questions, expecting for other users to provide them with answers. We focus on the task of question retrieval in cQA which aims to retrieve previous questions that are similar to new queries. The past answers related to the similar questions can be therefore used to respond to the new queries. The major challenges in this task are the shortness of the questions and the word mismatch problem as users can formulate the same query using different wording. Although question retrieval has been widely studied over the years, it has received less attention in Arabic and still requires a non trivial endeavour. In this paper, we focus on this task both in Arabic and English. We propose to use word embeddings, which can capture semantic and syntactic information from contexts, to vectorize the questions. In order to get longer sequences, questions are expanded with words having close word vectors. The embedding vectors are fed into the Siamese LSTM model to consider the global context of questions. The similarity between the questions is measured using the Manhattan distance. Experiments on real world Yahoo! Answers dataset show the efficiency of the method in Arabic and English.