(c) L3 = {w | w is a string of the form x1y1x2y2 . . . xnyn for some natural number n such that if x is the integer with binary representation x1x2 . . . xn and y is the integer with binary representation y1y2 . . . yn then x > y}. Both x and y are presented starting from the most significant bit and can have leading 0s.

(d) L4 = {w | w represents a possible series of flips in the game in which player 1 wins where H represents heads and T represents tails} where the game goes like this: Repeatedly flip a coin. On heads, player 1 gets a point. On tails, player 2 gets a point. A player wins (and the game ends) as soon as they are ahead by two points.