rewrite [Nat.div_lt_iff_lt_mul (ulp_pos n x)]
case h.h₂
x y n : ℕ
npos : 0 < n
h : trunc n x ≤ y
k : y < next n (trunc n x)
ulp_eq : ulp n x = ulp n y
⊢ y / ulp n x < x / ulp n x + 1
case h.h₂
x y n : ℕ
npos : 0 < n
h : trunc n x ≤ y
k : y < next n (trunc n x)
ulp_eq : ulp n x = ulp n y
⊢ y < (x / ulp n x + 1) * ulp n x