$x_i$ and $y_j$ are variables.
I intend to minimize this function and obtain the optimal value of $x$ and $y$:
$\begin{align} \frac{A_1}{y1}+B_1y_1+\frac{O1}{x1}+c_1\max\{x_1,y_1\}+\frac{A_2}{y1}+B_1y_1+\frac{O3}{x3}+c_3\max\{x_3,y_1\}+\frac{A2}{y2}+b_2y_2+C_2\max\{x_1,y_2\} \end{align}$