This set of notes provides a good overview of (some) of the work in the field of knowledge graphs and automated reasoning, including:
A history of ontology experiments on the web, i.e. attempts to extract structured relationships between online resources
A basic overview/tutorial of what knowledge graphs are and how to build them from text data
Slides from Google researchers about their methodology for extracting semantic relationships on a web scale (e.g. when you google a symptom, it will show you related disease information)
Some interesting papers on knowledge graphs and information extraction
More related fields and work, see the table of contents for the full list.
Hope that helps!