Theorem nnasuc

Description: Addition with successor. Theorem 4I(A2) of Enderton p. 79. (Contributed by NM, 20-Sep-1995) (Revised by Mario Carneiro, 14-Nov-2014)

	Ref	Expression
Assertion	nnasuc	⊢ ( ( 𝐴 ∈ ω ∧ 𝐵 ∈ ω ) → ( 𝐴 +o suc 𝐵 ) = suc ( 𝐴 +o 𝐵 ) )

Proof

Step	Hyp	Ref	Expression
1		nnon	⊢ ( 𝐴 ∈ ω → 𝐴 ∈ On )
2		onasuc	⊢ ( ( 𝐴 ∈ On ∧ 𝐵 ∈ ω ) → ( 𝐴 +o suc 𝐵 ) = suc ( 𝐴 +o 𝐵 ) )
3	1 2	sylan	⊢ ( ( 𝐴 ∈ ω ∧ 𝐵 ∈ ω ) → ( 𝐴 +o suc 𝐵 ) = suc ( 𝐴 +o 𝐵 ) )