b OR a AND b OR c AND a
# first, add parentheses for better disambiguation:
(b) OR (a AND b) OR (c AND a)
# now, sort the AND terms alphabetically, exploiting
# the commutativity of AND
(b) OR (a AND b) OR (a AND c)
# sort the outer terms alphabetically, exploiting
# the commutativity of OR
(a AND b) OR (a AND c) OR (b)
# this is the conjunctive normal form (I think)