Formula_19957

\[\begin{gathered}T\left(\varphi_{1}\left(x_{1}\right) \varphi_{2}\left(x_{2}\right)\right)=\theta\left(x_{1}^{0}-x_{2}^{0}\right) \varphi_{1}\left(x_{1}\right) \varphi_{2}\left(x_{2}\right)+ \\+\theta\left(x_{2}^{0}-x_{1}^{0}\right) \varphi_{2}\left(x_{2}\right) \varphi_{1}\left(x_{1}\right),\end{gathered}\]