Exercise 13.24

This exercise investigates the way in which conditional independence relationships affect the amount of information needed for probabilistic calculations.

  1. Suppose we wish to calculate $P(he_1,e_2)$ and we have no conditional independence information. Which of the following sets of numbers are sufficient for the calculation?

    1. ${\textbf{P}}(E_1,E_2)$, ${\textbf{P}}(H)$, ${\textbf{P}}(E_1H)$, ${\textbf{P}}(E_2H)$

    2. ${\textbf{P}}(E_1,E_2)$, ${\textbf{P}}(H)$, ${\textbf{P}}(E_1,E_2H)$

    3. ${\textbf{P}}(H)$, ${\textbf{P}}(E_1H)$, ${\textbf{P}}(E_2H)$

  2. Suppose we know that ${\textbf{P}}(E_1H,E_2)={\textbf{P}}(E_1H)$ for all values of $H$, $E_1$, $E_2$. Now which of the three sets are sufficient?

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