Dear all:

Due to formatting changes that occurred in set-typing the equations, some errors occurred in our article:

(1) In all equations, subscripts have been changed to regular fonts -- so, for example, Equation (1) should read p_i as opposed to pi. See below for more examples.

(2) Equation (2) should read O_i = p_i / (1 - p_i).

(3) Equation (3) should read p_i = (r_i + 1) / (r_i + w_i + 2).

(4) The left hand side of Equation (4) should read (r_i* + 1) / (w_i* + 1).

(5) The right hand side of Equation (5) should read (r_i + 1) / (w_i + 1).

Konstantinos and Andrew