Multiplicative Dependence Among Iterated Values of Rational Functions Modulo Finitely Generated Groups

Y We study multiplicative dependence between elements in orbits of algebraic dynamical systems over number fields modulo a finitely generated multiplicative subgroup of the field. We obtain a series of results, many of which may be viewed as a blend of Northcott's theorem on boundedness of preperiodic points and Siegel's theorem on finiteness of solutions to S-unit equations.