theorem
proved
term proof
interactionDefect_eq_zero_of_separatelyAdditive
show as:
view Lean formalization →
formal statement (Lean)
70theorem interactionDefect_eq_zero_of_separatelyAdditive
71 {P : ℝ → ℝ → ℝ} (h : SeparatelyAdditive P) :
72 ∀ u v : ℝ, interactionDefect P u v = 0 := by
proof body
Term-mode proof.
73 rcases h with ⟨p, q, hP⟩
74 intro u v
75 unfold interactionDefect
76 rw [hP u v, hP u 0, hP 0 v, hP 0 0]
77 ring
78
79/-- Conversely: a combiner whose interaction defect is identically zero is
80separately additive. The witness functions are `p(u) := P(u, 0) - P(0, 0)`
81and `q(v) := P(0, v)`. -/