Definition df-s2 11249

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

Assertion

Ref	Expression
df-s2	|- <" A B "> = ( <" 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 <" A B ">
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 <" A B "> = ( <" A "> ++ <" B "> )

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