have : (z.z : ℝ) = 0
case mp.z
a b c z : ℤα
h : OneHom.toFun (↑↑inclusion) z = 0
⊢ z.z = 0.z
case this
a b c z : ℤα
h : OneHom.toFun (↑↑inclusion) z = 0
⊢ ↑z.z = 0

case mp.z
a b c z : ℤα
h : OneHom.toFun (↑↑inclusion) z = 0
this : ↑z.z = 0
⊢ z.z = 0.z