題組內容

4.  Consider a vector of \(d\) independent binary random variables \(\mathbf{a} = [a_0, a_1, \cdots, a_{d-1}]\) in which \(\Pr(a_\ell = 1) = p_1^{(\ell)}\), \(\Pr(a_\ell = 0) = p_0^{(\ell)}\), and \(L_\ell = \ln(\frac{p_0^{(\ell)}}{p_1^{(\ell)}})\) for \(\ell = 0, 1, \cdots, d-1\).

(b) Please show that the probability that \(\mathbf{a}\) contains an even number of 1s is \(\frac{1}{2} + \frac{1}{2} \prod_{\ell=0}^{d-1} (1 - 2p_1^{(\ell)})\).