< Y_2$. The probability of the event can easily be computed and is equal to $\frac{1}{2}$. **Thus, contention is resolved in the first minislot whenever $0 \leq Y_1 \leq \frac{1}{2} < Y_2 \leq 1$ and the probability of the event is $\frac{1}{2}$; the threshold that resolves the contention successfully for the set $\{ (Y_1,Y_2) : 0 \leq Y_1 \leq \frac{1}{2} < Y_2 \leq 1\}$ is $\frac{1}{2}$ and the base station feeds back a $1$ in this case**. In the first minislot, an error due to collision occurs iff $\frac{1}{2} < Y_1 \leq Y_2$ and the slot is left idle iff $Y_1 \leq Y_2 \leq \frac{1}{2}$. Suppose that the feedback in the first minislot is $e$. Then, OSA updates the variables as $y_{low} = \frac{1}{2}, y_{min} = \frac{3}{4}$ and $y_{max} = 1$. In the second minislot, only the user(s) with $\frac{3}{4} < X_i$ transmit a control packet. A success happens now iff $Y_1 \leq \frac{3}{4} < Y_2$ and the conditional probability of the event (conditioned upon a collision in the first minislot) is $\frac{1}{2}$. **Thus, contention is resolved in the second minislot whenever $\frac{1}{2} < Y_1 \leq \frac{3}{4} < Y_2 \leq 1$ and the probability of the event is $\frac{1}{8}$; the 