This isn't really a blog post about a specific language feature so your question doesn't make too much sense to me, which may be why it hasn't gotten any answer

This isn't really a blog post about a specific language feature so your question doesn't make too much sense to me, which may be why it hasn't gotten any answers. In general, being able to map specific primitives to their derivatives is not sufficient for AD, although I'm sure AD is possible in C#, it's just considerably more involved than that.