+>> I appreciate the formalism!
+>>
+>> Only existing pages need to be in these sets, because if a page is added
+>> in the future, the existing dependency code will always test to see
+>> if it matches. So it will be in the maching set (or not) at that point.
+>>
+>>> Hrm, I agree with you in general, but I think I can come up with nasty counter-examples. What about a pagespec
+>>> of "!backlink(bogus)" where the page bogus doesn't exist? In this case, the page 'bogus' needs to be in the influence
+>>> set even though it doesn't exist.
+>>>
+>>>> I think you're right, this is a case that the current code is not
+>>>> handling. Actually, I made all the pagespecs return influences
+>>>> even if the influence was not present or did not match. But, it
+>>>> currently only records influences as dependencies when a pagespec
+>>>> successfully matches. Now I'm sure that is wrong, and I've removed
+>>>> that false optimisation. I've updated some of the below. --[[Joey]]
+>>>
+>>> Also, I would really like the formalism to include the whole dependency system, not just any additions to it. That will make
+>>> the whole thing much easier to reason about.
+>>
+>> The problem with your definition of direct influence set seems to be
+>> that it doesn't allow `link()` and `title()` to have as an indirect
+>> influence, the page that matches. But I'm quite sure we need those.
+>> --[[Joey]]
+
+>>> I see what you mean. Does the revised definition capture this effectively?
+>>> The problem with this revised definition is that it still doesn't match your examples below.
+>>> My revised definition will include pretty much all currently matching pages to be in the influence list
+>>> because deletion of any of them would cause a change in which pages are matched - the removal problem.
+>>> -- [[Will]]
+