This paper presents an ecosystem for personal knowledge graphs (PKG), commonly defined as resources of structured information about entities related to an individual, their attributes, and the relations between them. PKGs are a key enabler of secure and sophisticated personal data management and personalized services. However, there are challenges that need to be addressed before PKGs can achieve widespread adoption. One of the fundamental challenges is the very definition of what constitutes a PKG, as there are multiple interpretations of the term. We propose our own definition of a PKG, emphasizing the aspects of (1) data ownership by a single individual and (2) the delivery of personalized services as the primary purpose. We further argue that a holistic view of PKGs is needed to unlock their full potential, and propose a unified framework for PKGs, where the PKG is a part of a larger ecosystem with clear interfaces towards data services and data sources. A comprehensive survey and synthesis of existing work is conducted, with a mapping of the surveyed work into the proposed unified ecosystem. Finally, we identify open challenges and research opportunities for the ecosystem as a whole, as well as for the specific aspects of PKGs, which include population, representation and management, and utilization.

翻译：本文提出了个人知识图谱（PKG）的生态系统概念。PKG通常被定义为关于个体相关实体的结构化信息资源，包括实体属性及其相互关系。PKG是实现安全且精细的个人数据管理与个性化服务的关键支撑技术。然而，在PKG实现广泛采用之前，仍存在若干亟需解决的挑战。根本性挑战之一在于PKG的定义本身——该术语存在多种解释。我们提出了PKG的专属定义，强调两个核心要素：（1）数据由单一个体所有，（2）提供个性化服务作为首要目标。我们进一步论证，需要以全局视角审视PKG才能释放其全部潜力，并提出了PKG的统一框架。在该框架中，PKG作为更大生态系统的一部分，与数据服务和数据源之间存在清晰接口。本文对现有研究进行了系统性综述与综合，将相关研究成果映射至所提出的统一生态系统。最后，我们识别了整个生态系统以及PKG特定环节（包括构建、表示与管理、应用）所面临的开放性挑战与研究机遇。