Definition df-s4 11251

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

Assertion

Ref	Expression
df-s4	|- <" A B C D "> = ( <" A B C "> ++ <" 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 <" A B C D ">
6	1, 2, 3	cs3 11243	. . 3 class <" A B C ">
7	4	cs1 11109	. . 3 class <" D ">
8		cconcat 11086	. . 3 class ++
9	6, 7, 8	co 5969	. 2 class ( <" A B C "> ++ <" D "> )
10	5, 9	wceq 1373	1 wff <" A B C D "> = ( <" A B C "> ++ <" D "> )

This definition is referenced by:  s4eqd  11265  s4cld  11273