Based on a real world use case, we developed and evaluated a hybrid AI system that aims to extract key elements from legal permits by combining methods from the Semantic Web and Machine Learning. Specifically, we modelled the available background knowledge in a custom Knowledge Graph, which we exploited together with the usage of different language- and text-embedding-models in order to extract different information from official Austrian permits, including the Issuing Authority, the Operator of the facility in question, the Reference Number, and the Issuing Date. Additionally, we implemented mechanisms to capture automatically auditable traces of the system to ensure the transparency of the processes. Our quantitative evaluation showed overall promising results, while the in-depth qualitative analysis revealed concrete error types, providing guidance on how to improve the current prototype.

In line with the general trend in artificial intelligence research to create intelligent systems that combine learning and symbolic components, a new sub-area has emerged that focuses on combining machine learning (ML) components with techniques developed by the Semantic Web (SW) community – Semantic Web Machine Learning (SWeML for short). Due to its rapid growth and impact on several communities in the last two decades, there is a need to better understand the space of these SWeML Systems, their characteristics, and trends. Yet, surveys that adopt principled and unbiased approaches are missing. To fill this gap, we performed a systematic study and analyzed nearly 500 papers published in the last decade in this area, where we focused on evaluating architectural, and application-specific features. Our analysis identified a rapidly growing interest in SWeML Systems, with a high impact on several application domains and tasks. Catalysts for this rapid growth are the increased application of deep learning and knowledge graph technologies. By leveraging the in-depth understanding of this area acquired through this study, a further key contribution of this paper is a classification system for SWeML Systems which we publish as ontology.