If you are interested in seeing what this software package can do, as I was, you might want to check out the quickstart example: https://www.ory.sh/keto/docs/quickstart

and an example: https://www.ory.sh/keto/docs/examples/olymp-file-sharing

as well as the concepts section: https://www.ory.sh/keto/docs/concepts/relation-tuples

as well as their implemented and planned features: https://www.ory.sh/keto/docs/implemented-planned-features