While obviously not rigorous enough for something serious, one obvious hack is to do the "0.5 unless proven" thing, and then have a long list of special case dumb heuristics with different weights that update that without any proofs involved at all. The list of heuristics could be gotten from some unsafe source like the programer or another AI or mechanical turk, and then the weights learned by first guessing and then proving to see if it was right, with heuristics that are to bad kicked out entirely.