+- use regression/least-squares/trend-prof to look for reductions whose
+ behavior is O(n^2)? (ie performed a number of times proportional to
+ the input consumed so far).
+
+- Optimizations:
+ - (x &~ y) => (x & z)
+ - string lookahead
+ - don't form result forests for negated productions
+ - early kills: (a &~ ... b ...) -> once "... b" is seen, "a" is dead
+