# A Survey on Multi-User Conversational Interfaces
## 6 Conclusions and Outlook  
Concerning research on MUCIs, there exist several factors that make it difficult for authors to communicate their findings effectively and establish collaborations. One of the main challenges is the lack of a unified community, as has been highlighted in this survey paper. As a result, researchers across MU topics often employ their own distinct terminology, utilise diverse methodologies, and approach research questions from different perspectives. However, this impairs mutual understanding of each other's work and discourages effective collaboration. To address these challenges, it seems essential to enhance the perspicuity and visibility of publications. This involves using standardised terminology and avoiding ambiguous or personalised definitions, acronyms, and unique jargon that may confuse or mislead readers. By improving the perspicuity of their work, researchers can increase its impact and make it easier for others to build upon their findings. Additionally, research dissemination channels such as journals, conferences, and workshops can foster visibility and interdisciplinary collaboration by expanding platforms and discussions on Multi-User Conversational Interfaces. To build a stronger and more integrated community, it is crucial to connect people with diverse expertise, enabling them to face future challenges. As an initial step toward unifying the discourse, incorporating the definition proposed in this work could help align future publications under a shared understanding and consistent terminology. In the context of the reviewed literature, most publications focus on scenarios in which two users interact with a single conversational interface. The reason for this may be that the complexity of the interface increases significantly as the number of supported users grows. In contrast, several papers had to be excluded from our survey because, despite being labelled as multi-user, the authors are actually referring to the sequential processing of single-user inputs and not to their simultaneous handling. Despite significant research and development in the field, there is no implemented system that has gained widespread adoption, neither in an industrial or academic context. Instead, most researchers have focused on developing and evaluating prototypical systems or frameworks. These systems are designed to showcase new ideas and concepts and often feature novel technologies and experimental designs. However, the implementation of underlying dialogue models remains frequently incomplete, and many of these systems are not yet fully implemented for for real-world deployment. Due to this, multi-user conversation is still more of a laboratory use case that is being explored in controlled environments. In particular, almost all of publications of our sample used different dialogue and user models. This poses a barrier to the generalisability and broader applicability of presented MUCIs. Several publications investigated on equipping virtual agents or robots with conversational interfaces. For this, both hardware and software components of systems need capabilities to deal with multiple users. It requires expertise in robotics, artificial intelligence, and computer science, among other fields. Furthermore, robotics research often involves significant hardware development, which can be expensive and time-consuming. Robotics is also heavily depending on multi-modality, as effective communication with embodied user interfaces requires the integration of visual, audio, and tactile inputs to interpret user intents, respond appropriately, and adapt to dynamic environments in real-time. Another unresolved challenge lies in the evaluation of MUCIs, as current methods often lack consistency and fail to capture the complex interactions involved. Developing comprehensive and standardised evaluation frameworks is essential to ensure meaningful comparisons and guide future improvements.