\frac{dx_{1}}{dt} = \left(1 \cdot k_{16} \cdot k_{1} + -1 \cdot k_{16} \cdot k_{2} \cdot x_{1} + -1 \cdot k_{16} \cdot k_{9} \cdot x_{2} \cdot x_{1}\right) / k_{16}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{16} \cdot k_{5} + -1 \cdot k_{16} \cdot k_{6} \cdot x_{2} + -1 \cdot k_{16} \cdot k_{9} \cdot x_{2} \cdot x_{1} + -1 \cdot k_{16} \cdot k_{10} \cdot x_{2} \cdot x_{3} + 1 \cdot k_{16} \cdot k_{11} / \left(k_{12} / \operatorname{delay}\left(x_{4}, k_{14}\right)^{k_{13}} + 1\right)\right) / k_{16}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{16} \cdot k_{3} + -1 \cdot k_{16} \cdot k_{4} \cdot x_{3} + -1 \cdot k_{16} \cdot k_{10} \cdot x_{2} \cdot x_{3}\right) / k_{16}\\
\frac{dx_{4}}{dt} = \left(-1 \cdot k_{16} \cdot k_{8} \cdot x_{4} + 1 \cdot k_{16} \cdot k_{7} \cdot \operatorname{delay}\left(x_{3}, k_{15}\right)\right) / k_{16}