The main theorem asserts
that Sζ(D) = S(D) ∩ℳζ(D), where D is a polydomain in Cn,S(D) is the Shilov
boundary of H∞(D),ζ is an essential distinguished boundary point of D,ℳζ(D) is
the fiber over ζ of the maximal ideal space of H∞(D), and Sζ(D) is the Shilov
boundary of the fiber algebra. The main theorem includes Iversen’s theorem for
polydomains.