Definition df-s2 11441

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 11434	. 2 class <" A B ">
4	1	cs1 11296	. . 3 class <" A ">
5	2	cs1 11296	. . 3 class <" B ">
6		cconcat 11271	. . 3 class ++
7	4, 5, 6	co 6049	. 2 class ( <" A "> ++ <" B "> )
8	3, 7	wceq 1398	1 wff <" A B "> = ( <" A "> ++ <" B "> )

This definition is referenced by:  cats2catd  11454  s2eqd  11455  s2cld  11463  s2fv0g  11472  s2fv1g  11473  s2leng  11474  s1s2d  11479  s2s2d  11485  s4s2d  11486  s2s5d  11489  s5s2d  11490  konigsberglem1  16470  konigsberglem2  16471  konigsberglem3  16472