HETS (the heterogeneous tool set) is explained as follows:
Hets is a parsing, static analysis and proof management tool incorporating various provers and different specification languages, thus providing a tool for heterogeneous specifications. Logic translations are first-class citizens.
There is a user guide. BE SURE to watch this short video. Frankly, I don't know exactly what this is, but it seems important. The interfaces are interesting.
There is a video, and in the video they use a tool called uDrawGraph. That is likewise very interesting. This is a information related to using uDrawGraph. This description of uDrawGraph is important:
uDraw(Graph) is an interactive tool to visualize directed graphs.
Why is that important? Note the phrase "directed graphs". As I have pointed out in the past, that word "directed" is critically important. Also, the term "graph" is important as contrast to "tree".
Along these same lines is this paper which explains a safe extension of DATALOG.
More to come...