this is the same as "fsharpanimalquiz" repo (https://github.com/tonyx/fsharpanimalquiz) except that here you can run it in a simple gtk box by addin the parameter "gui" on the command line.
(note: at the moment I keep those project separately, just to make sure there is still one that doesn't require gtk lib in build)
This code is related to a serie of blog posts
first version, console based application: http://tonyxzt.blogspot.it/2014/02/animal-quiz-problem-in-f.html
second version, adding gtk# gui: blog post: http://tonyxzt.blogspot.it/2016/09/adding-simple-gtk-gui-in-console-f.html
third version, using xml and xml schema validation for loading and saving a knowledge tree: http://tonyxzt.blogspot.it/2016/10/managing-decision-trees-in-xml-in-f-and.html