Theorem lidrididd 12613

Description: If there is a left and right identity element for any binary operation (group operation) .+, the left identity element (and therefore also the right identity element according to lidrideqd 12612) is equal to the two-sided identity element. (Contributed by AV, 26-Dec-2023.)

Hypotheses

Ref	Expression
lidrideqd.l	|- ( ph -> L e. B )
lidrideqd.r	|- ( ph -> R e. B )
lidrideqd.li	|- ( ph -> A. x e. B ( L .+ x ) = x )
lidrideqd.ri	|- ( ph -> A. x e. B ( x .+ R ) = x )
lidrideqd.b	|- B = ( Base ` G )
lidrideqd.p	|- .+ = ( +g ` G )
lidrididd.o	|- .0. = ( 0g ` G )

Assertion

Ref	Expression
lidrididd	|- ( ph -> L = .0. )

Distinct variable groups:   x, B   x, L   x, R   x, .+

Allowed substitution hints:   ph( x)   G( x)   .0. ( x)

Proof of Theorem lidrididd

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		lidrideqd.b	. 2 |- B = ( Base ` G )
2		lidrididd.o	. 2 |- .0. = ( 0g ` G )
3		lidrideqd.p	. 2 |- .+ = ( +g ` G )
4		lidrideqd.l	. 2 |- ( ph -> L e. B )
5		lidrideqd.li	. . 3 |- ( ph -> A. x e. B ( L .+ x ) = x )
6		oveq2 5850	. . . . 5 |- ( x = y -> ( L .+ x ) = ( L .+ y ) )
7		id 19	. . . . 5 |- ( x = y -> x = y )
8	6, 7	eqeq12d 2180	. . . 4 |- ( x = y -> ( ( L .+ x ) = x <-> ( L .+ y ) = y ) )
9	8	rspcv 2826	. . 3 |- ( y e. B -> ( A. x e. B ( L .+ x ) = x -> ( L .+ y ) = y ) )
10	5, 9	mpan9 279	. 2 |- ( ( ph /\ y e. B ) -> ( L .+ y ) = y )
11		lidrideqd.ri	. . . 4 |- ( ph -> A. x e. B ( x .+ R ) = x )
12		lidrideqd.r	. . . . 5 |- ( ph -> R e. B )
13	4, 12, 5, 11	lidrideqd 12612	. . . 4 |- ( ph -> L = R )
14		oveq1 5849	. . . . . . . 8 |- ( x = y -> ( x .+ R ) = ( y .+ R ) )
15	14, 7	eqeq12d 2180	. . . . . . 7 |- ( x = y -> ( ( x .+ R ) = x <-> ( y .+ R ) = y ) )
16	15	rspcv 2826	. . . . . 6 |- ( y e. B -> ( A. x e. B ( x .+ R ) = x -> ( y .+ R ) = y ) )
17		oveq2 5850	. . . . . . . . 9 |- ( L = R -> ( y .+ L ) = ( y .+ R ) )
18	17	adantl 275	. . . . . . . 8 |- ( ( ( y .+ R ) = y /\ L = R ) -> ( y .+ L ) = ( y .+ R ) )
19		simpl 108	. . . . . . . 8 |- ( ( ( y .+ R ) = y /\ L = R ) -> ( y .+ R ) = y )
20	18, 19	eqtrd 2198	. . . . . . 7 |- ( ( ( y .+ R ) = y /\ L = R ) -> ( y .+ L ) = y )
21	20	ex 114	. . . . . 6 |- ( ( y .+ R ) = y -> ( L = R -> ( y .+ L ) = y ) )
22	16, 21	syl6com 35	. . . . 5 |- ( A. x e. B ( x .+ R ) = x -> ( y e. B -> ( L = R -> ( y .+ L ) = y ) ) )
23	22	com23 78	. . . 4 |- ( A. x e. B ( x .+ R ) = x -> ( L = R -> ( y e. B -> ( y .+ L ) = y ) ) )
24	11, 13, 23	sylc 62	. . 3 |- ( ph -> ( y e. B -> ( y .+ L ) = y ) )
25	24	imp 123	. 2 |- ( ( ph /\ y e. B ) -> ( y .+ L ) = y )
26	1, 2, 3, 4, 10, 25	ismgmid2 12611	1 |- ( ph -> L = .0. )

Syntax hints:   -> wi 4   /\ wa 103   = wceq 1343   e. wcel 2136   A.wral 2444   ` cfv 5188  (class class class)co 5842   Basecbs 12394   +g cplusg 12457   0gc0g 12573

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-13 2138  ax-14 2139  ax-ext 2147  ax-sep 4100  ax-pow 4153  ax-pr 4187  ax-un 4411  ax-cnex 7844  ax-resscn 7845  ax-1re 7847  ax-addrcl 7850

This theorem depends on definitions:  df-bi 116  df-3an 970  df-tru 1346  df-nf 1449  df-sb 1751  df-eu 2017  df-mo 2018  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-ral 2449  df-rex 2450  df-reu 2451  df-rmo 2452  df-rab 2453  df-v 2728  df-sbc 2952  df-csb 3046  df-un 3120  df-in 3122  df-ss 3129  df-pw 3561  df-sn 3582  df-pr 3583  df-op 3585  df-uni 3790  df-int 3825  df-br 3983  df-opab 4044  df-mpt 4045  df-id 4271  df-xp 4610  df-rel 4611  df-cnv 4612  df-co 4613  df-dm 4614  df-rn 4615  df-res 4616  df-iota 5153  df-fun 5190  df-fn 5191  df-fv 5196  df-riota 5798  df-ov 5845  df-inn 8858  df-ndx 12397  df-slot 12398  df-base 12400  df-0g 12575

This theorem is referenced by: (None)