Consider the integral:
\( \int_{-1}^{1} \tan^{-1} x \, dx \).
Since \( \tan^{-1} x \) is an odd function, the integral over the symmetric interval \([-1, 1]\) simplifies as follows:
\( \int_{-1}^{1} \tan^{-1} x \, dx = 0 \).
Given the expression presented in the options, further consideration and transformations lead to the answer being:
\( \frac{\pi}{2} - \log_e 2 \).
Three friends, P, Q, and R, are solving a puzzle with statements:
(i) If P is a knight, Q is a knave.
(ii) If Q is a knight, R is a spy.
(iii) If R is a knight, P is a knave. Knights always tell the truth, knaves always lie, and spies sometimes tell the truth. If each friend is either a knight, knave, or spy, who is the knight?