“…The trend of using both extractive-based and generative-based AI methods for chatbots is gaining popularity. Many methods of NLP, as well as NLU [13,21,25,30], ML [24,27,30,36,37,62], and deep learning, including RNN, LSTM, GRU, encoder-decoders, Seq2Seq [5,17,21,28,31,38,[48][49][50][51][52][53][54][55]57], and reinforcement learning [56,57,60,61], have been successfully applied in research related to chatbots and conversational dialogs. Table 2 summarizes several research works that were conducted using these models, the datasets used, and their advantages and disadvantages from our perspective.…”