  In this dissertation I would like to guide the reader to the research on
dialogue but more precisely the research I have conducted during my career
since my PhD thesis. Starting from modular architectures with machine
learning/deep learning and reinforcement learning to end-to-end deep neural
networks. Besides my work as research associate, I also present the work I have
supervised in the last years.
  I review briefly the state of the art and highlight the open research
problems on conversational agents. Afterwards, I present my contribution to
Task-Oriented Dialogues (TOD), both as research associate and as the industrial
supervisor of CIFRE theses. I discuss conversational QA. Particularly, I
present the work of two PhD candidates Thibault Cordier and Sebastien Montella;
as well as the work of the young researcher Quentin Brabant. Finally, I present
the scientific project, where I discuss about Large Language Models (LLMs) for
Task-Oriented Dialogue and Multimodal Task-Oriented Dialogue.
