2. Let ¥ = {0,1} and A= {0,1,¢}. This models an erasure option, ic. a method of saying “I don’t know
what the state is”. Suppose that the observation distributions are Gaussian with mean depending on
the state: Py = N(—1,07) and P; = N (1,07). Suppose that the cost has the following structure,
parameterized by 0 < e:
c(0,0) C(0,1) C(O,e)\ fO 1 e
ce,0) C,1) CU,e)/ ~\1 0 ce)”
Assume that the prior is symmetric: (0) = a(1) = 1/2.
(a) Show that if ¢ < 1/2, the Bayes rule has the form
0 y<-t
Ony)= Ve -t
l t
and find an expression for ¢ in terms of the parameters of the problem
(b) Find 6g when c¢ > 1/2.