EquivRel(ℕ+ ⟶ ℤ;f,g.bdd-diff(f;g))
{ RepeatFor 2 ((D 0 THEN Auto)) }
1. a : ℕ+ ⟶ ℤ
⊢ bdd-diff(a;a)
1. a : ℕ+ ⟶ ℤ
2. b : ℕ+ ⟶ ℤ
3. bdd-diff(a;b)
⊢ bdd-diff(b;a)
1. Sym(ℕ+ ⟶ ℤ;f,g.bdd-diff(f;g))
2. a : ℕ+ ⟶ ℤ
3. b : ℕ+ ⟶ ℤ
4. c : ℕ+ ⟶ ℤ
5. bdd-diff(a;b)
6. bdd-diff(b;c)
⊢ bdd-diff(a;c)