Definition df-s4 11251

Description: Define the length 4 word constructor. (Contributed by Mario Carneiro, 26-Feb-2016.)

Assertion

Ref	Expression
df-s4	⊢ ⟨“𝐴𝐵𝐶𝐷”⟩ = (⟨“𝐴𝐵𝐶”⟩ ++ ⟨“𝐷”⟩)

Detailed syntax breakdown of Definition df-s4

Step	Hyp	Ref	Expression
1		cA	. . 3 class 𝐴
2		cB	. . 3 class 𝐵
3		cC	. . 3 class 𝐶
4		cD	. . 3 class 𝐷
5	1, 2, 3, 4	cs4 11244	. 2 class ⟨“𝐴𝐵𝐶𝐷”⟩
6	1, 2, 3	cs3 11243	. . 3 class ⟨“𝐴𝐵𝐶”⟩
7	4	cs1 11109	. . 3 class ⟨“𝐷”⟩
8		cconcat 11086	. . 3 class ++
9	6, 7, 8	co 5969	. 2 class (⟨“𝐴𝐵𝐶”⟩ ++ ⟨“𝐷”⟩)
10	5, 9	wceq 1373	1 wff ⟨“𝐴𝐵𝐶𝐷”⟩ = (⟨“𝐴𝐵𝐶”⟩ ++ ⟨“𝐷”⟩)

This definition is referenced by:  s4eqd  11265  s4cld  11273