change ((a + -b : ℤα) : ℂ) = a + -(b : ℂ)
a b c : ℤα
⊢ OneHom.toFun (↑↑inclusion) (a - b) = OneHom.toFun (↑↑inclusion) a - OneHom.toFun (↑↑inclusion) b
a b c : ℤα
⊢ OneHom.toFun (↑↑inclusion) (a + -b) = OneHom.toFun (↑↑inclusion) a + -OneHom.toFun (↑↑inclusion) b