Some years ago (I'm guessing about 5), I found a really cool project through HN. It was desktop software written by one person and they had put up a website with a really well edited and narrated demo video. The software was a sort of wiki/notes platform on steroids. It had semantic associations and I'm finding it difficult to describe. I believe the example document in the video was a maths or physics topic. Hoping someone else remembers this and has a link or more info, as I've tried several times to find it again without avail.

Edit: Closest thing I've found is Contextualise, but it's definitely not that. https://github.com/brettkromkamp/contextualise