"Well, I'm starting to run out of room on this whiteboard, so forgive me if I write that down in dath ilani shorthand," says Keltham.
\ z. t1(z) -> ~t2(z)
\ h. t3(h) -> t2(h)
__________________
\ q. t1(q) -> ~t3(q)
"Now this is a valid reasoning rule to be sure," says Keltham, "but just like dividing over a balanced equation can be seen as multiplying by an inverse, I think we don't need to add this whole rule to our entity. The form of this rule looks really quite similar, in some ways, to that earlier rule about Z-generalized, H-generalized, and Q-generalized. I think we can add a smaller rule to our entity, which already has that rule, and get this rule back out as a special case - like adding the inverse operation to an algebra that already has the rule about multiplying over a balanced equation, and automatically getting out the power to divide over a balanced equation."
"I don't think, based on your past performance, that you can derive the missing rule on your own; but beliefs like that ought to be tested rather than just assumed. Wanna surprise me?"