Welcome, Kathryn! I recognize the mark of a kindred spirit in your grammarian ways, even though I cannot quite follow you into the intricacies of higher math (though I do have a sneaking interest in that Calculus proof you mention, and if I can't make it out, my math genius father should be able to explain it to me).

Also, I'm psyched to make the acquaintance of a Philadelphian! My husband and I will be moving there to work at Esperanza Health Care Center in December 2011. So, perhaps I'll be picking your brain for places to visit and other such local wisdom!