$$ \begin{array}{ll} |\forall y (y \in \dot{x} \wedge \psi(y) \Longrightarrow y \in \dot{v})| &= \inf_t (|y \in \dot{v}| - |y \in \dot{x}||\varphi(y)|) \\ \\ &= \inf_t (\sup_{k \in dom(\dot{v})} \dot{v}(k)|y=k| - \sup_{g \in dom(\dot{v})} \dot{x}(g)|y=g||\varphi(y)|) \\ \\ &\geq \inf_t \sup_{k \in dom(\dot{v})} |y=k|\cdot (\dot{v}(k) - \dot{x}(k)|\varphi(k)|) \\ \\ &= \inf_t \sup_{k \in dom(\dot{v})} |y=k|\cdot(\dot{x}(k)|\varphi(k)| - \dot{x}(k)|\varphi(k)|) \\ \\ &= \inf_t \sup_{k \in dom(\dot{v})} \emptyset = \inf_t \emptyset = 1, \\ \\ &\text{Assim, } |\varphi_2| = 1 \end{array} $$ $\square$