Posting has been a bit limited due to a combination of things. Some is work related. For example, as much as I would like, the following explanation as to Why I ought not to be concerned with Vf is really not a good blog subject.
I am always impressed with the creative skills that some folks have that uses the language of math to describe things with a precision that English can not do. In this case a timely paper (for me) by Bouchet and others (2016). It takes a bit of extended concentration to work through what I am after on this matter as well as an openness as to not getting to the answer or clarity I would like. However, this particular explanation (one of several) was of some help.