∀[n,m:ℕ+]. ℤ_n ⋃ ℤ_m ≡ ℤ_gcd(n;m)
{ (Auto THEN RepeatFor 2 (D 0) THEN Auto) }
.....subterm..... T:t
1:n
1. n : ℕ+
2. m : ℕ+
3. x : ℤ_n ⋃ ℤ_m
⊢ x ∈ ℤ_gcd(n;m)
3. x : ℤ_gcd(n;m)
⊢ x ∈ ℤ_n ⋃ ℤ_m