Definition df-s2 11338

Description: Define the length 2 word constructor. (Contributed by Mario Carneiro, 26-Feb-2016.)

Assertion

Ref	Expression
df-s2	⊢ ⟨“𝐴𝐵”⟩ = (⟨“𝐴”⟩ ++ ⟨“𝐵”⟩)

Detailed syntax breakdown of Definition df-s2

Step	Hyp	Ref	Expression
1		cA	. . 3 class 𝐴
2		cB	. . 3 class 𝐵
3	1, 2	cs2 11331	. 2 class ⟨“𝐴𝐵”⟩
4	1	cs1 11193	. . 3 class ⟨“𝐴”⟩
5	2	cs1 11193	. . 3 class ⟨“𝐵”⟩
6		cconcat 11168	. . 3 class ++
7	4, 5, 6	co 6018	. 2 class (⟨“𝐴”⟩ ++ ⟨“𝐵”⟩)
8	3, 7	wceq 1397	1 wff ⟨“𝐴𝐵”⟩ = (⟨“𝐴”⟩ ++ ⟨“𝐵”⟩)

This definition is referenced by:  cats2catd  11351  s2eqd  11352  s2cld  11360  s2fv0g  11369  s2fv1g  11370  s2leng  11371