of cooperation. Nature 555242-245. 19. Brandt H. Sigmund K (2004) The logic of reprobation: Assessment and action rules for Indirect reciprocation. Theor Blot 231:475-486. 20. Ohtwki µ Iwasa Y (2004) How should we define goodness?—Reputation dynamics In indirect reciprocity. Theo, VW 231:107-120. 21. Nowak MA, Sigmu