Definition df-s2 11249

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 11242	. 2 class ⟨“𝐴𝐵”⟩
4	1	cs1 11109	. . 3 class ⟨“𝐴”⟩
5	2	cs1 11109	. . 3 class ⟨“𝐵”⟩
6		cconcat 11086	. . 3 class ++
7	4, 5, 6	co 5969	. 2 class (⟨“𝐴”⟩ ++ ⟨“𝐵”⟩)
8	3, 7	wceq 1373	1 wff ⟨“𝐴𝐵”⟩ = (⟨“𝐴”⟩ ++ ⟨“𝐵”⟩)

This definition is referenced by:  cats2catd  11262  s2eqd  11263  s2cld  11271  s2fv0g  11280  s2fv1g  11281  s2leng  11282