$$ \begin{array}{ll} |\forall y \in \dot{x} \varphi(y)| &= \inf_{t}|t \in \dot{x} \Longrightarrow \varphi(t)| \\ \\ &=\inf_{t}(-|t \in \dot{x}|+|\varphi(t)|) \\ \\ &=\inf_{t}(|\varphi(t)|-\sup_{y \in \text{dom}(\dot{x})}|t=y|\dot{x}(y)) \\ \\ &=\inf_{t}(|\varphi(t)|+\inf_{y \in \text{dom}(\dot{x})}(-|t=y|-\dot{x}(y))) \\ \\ &=\inf_{t}\inf_{y \in \text{dom}(\dot{x})}(|\varphi(t)|-|t=y|-\dot{x}(y)) \\ \\ &=\inf_{y \in \text{dom}(\dot{x})}\inf_{t}(-\dot{x}(y)-|t=y|+|\varphi(t)|) \end{array} $$ $\square$