Joint Colloquium: Silver -- When knots don't fiber

In this joint work with Susan Williams we consider the conjecture:
a knot is nonfibered if and only if its infinite cyclic cover has 
uncountably many finite covers. We prove it for a class of knots that 
includes all knots of genus 1. We also discuss two equivalent forms of
the conjecture, one involving twisted Alexander polynomials, the other 
a weak form of subgroup separability.

[Notes added by JAH. 
(1) This is in Carslaw 175, not the usual room.
(2) Susan Williams shall be giving a JC on
    "Knots and Algebraic Dynamical Systems" 
(also joint work with Dan Silver) at UNSW, on Thursday 24 April. 
Details shall be posted separately.]