Well, the hidden virtuals conflict with the unusual vector configuration leading to easy identification of the unconfigured rectangles. Hope this helps.
Difficulty score 73. Not exactly easy, but fairly straight forward with green.
And no guesses.
Ahhh, yes, Angie. I see where I erred now. I got impaled on trying to resolve whether there was a unique hidden variable constant or a redundant constant variable mucking up the works. I do find these experts quite beneficial in building an aversion for single syllable four letter words. Not really. Just watched Sherlock on TIVO and can't get that voice out of my head.
73? That's Ham lingo for best regards, Doc. Reduced it down to the last two boxes when it failed, LOL, LOL. #@$%!
Time to bug out.
I do not know the formulas you use, but for some reason, I could see the answer- very strange
Did it, no green, one lucky guess and one short, easy chain loop.