Consider a system with $m$ resources and 4 threads: $T_0$, $T_1$, $T_2$, and $T_3$. Let $x_i$ and $y_i$ denote the maximum number of resources requested and the current number of resources held by thread $T_i$, respectively, for all $i$, $0 \le i \le 3$. Which of the following statement(s) are correct?