[QUE/QFT-14001] QFT-PROBLEM

Prove that \begin{equation} \int_{t_0}^ t \, dt_1 \int_{t_0}^ {t_1} dt_2\, H^\prime_I(t_1) H^\prime_I(t_2) = \frac{1}{2} \int_{t_0}^ t \, dt_1 \int_{t_0}^ t \, dt_2 T\big( H^\prime_I(t_1) H^\prime_I(t_2)\big) \end{equation}