In the Definition 11.3.2 (Cauchy reals and Cauchy approximations), the relation ~ is given two different types ℚ₊ × ℝ × ℝ → U and ℝ → ℝ → ℚ₊ → U. ~_ε : ℝ → ℝ → Prop is also used in the text.
This can be represented by a family of binary relations, which we will denote ∼_e : ℝ → ℝ → Prop.
It would be better to unify the convention.
In the Definition 11.3.2 (Cauchy reals and Cauchy approximations), the relation ~ is given two different types
ℚ₊ × ℝ × ℝ → Uandℝ → ℝ → ℚ₊ → U.~_ε : ℝ → ℝ → Propis also used in the text.It would be better to unify the convention.