TOBU is a novel mobile application that captures and retrieves `personal memories' (pictures/videos together with stories and context around those moments) in a user-engaging AI-guided conversational approach. Our initial prototype showed that existing retrieval techniques such as retrieval-augmented generation (RAG) systems fall short due to their limitations in understanding memory relationships, causing low recall, hallucination, and unsatisfactory user experience. We design TOBUGraph, a novel graph-based retrieval approach. During capturing, TOBUGraph leverages large language models (LLMs) to automatically create a dynamic knowledge graph of memories, establishing context and relationships of those memories. During retrieval, TOBUGraph combines LLMs with the memory graph to achieve comprehensive recall through graph traversal. Our evaluation using real user data demonstrates that TOBUGraph outperforms multiple RAG implementations in both precision and recall, significantly improving user experience through improved retrieval accuracy and reduced hallucination.

Artificial intelligence (AI) can improve human decision-making in various application areas. Ideally, collaboration between humans and AI should lead to complementary team performance (CTP) -- a level of performance that neither of them can attain individually. So far, however, CTP has rarely been observed, suggesting an insufficient understanding of the complementary constituents in human-AI collaboration that can contribute to CTP in decision-making. This work establishes a holistic theoretical foundation for understanding and developing human-AI complementarity. We conceptualize complementarity by introducing and formalizing the notion of complementarity potential and its realization. Moreover, we identify and outline sources that explain CTP. We illustrate our conceptualization by applying it in two empirical studies exploring two different sources of complementarity potential. In the first study, we focus on information asymmetry as a source and, in a real estate appraisal use case, demonstrate that humans can leverage unique contextual information to achieve CTP. In the second study, we focus on capability asymmetry as an alternative source, demonstrating how heterogeneous capabilities can help achieve CTP. Our work provides researchers with a theoretical foundation of complementarity in human-AI decision-making and demonstrates that leveraging sources of complementarity potential constitutes a viable pathway toward effective human-AI collaboration.