theorem
proved
term proof
sub_contains_sub
show as:
view Lean formalization →
formal statement (Lean)
96theorem sub_contains_sub {x y : ℝ} {I J : Interval}
97 (hx : I.contains x) (hy : J.contains y) : (I - J).contains (x - y) := by
proof body
Term-mode proof.
98 constructor
99 · simp only [sub_lo, Rat.cast_sub]
100 exact sub_le_sub hx.1 hy.2
101 · simp only [sub_hi, Rat.cast_sub]
102 exact sub_le_sub hx.2 hy.1
103
104/-- Multiplication for positive intervals -/