WEBS, ITERATION GROUPS, AND EQUIVALENT CHANGES IN PROBABILITIES

Yew-Kwang Ng [12] listed several ''reasonable properties'' for equival ent changes of probabilities and other proportions. He produced a fami ly of functions satisfying all properties and asked whether there exis t essentially different ones. We show that this is the case, by constr ucting uncountably many families of functions satisfying all propertie s. We show also that there are no other solutions. Our method establis hes connections with webs (nets) and iteration groups. This may be of interest bath in itself and for applications.