Theorem rhmopp 13732

Description: A ring homomorphism is also a ring homomorphism for the opposite rings. (Contributed by Thierry Arnoux, 27-Oct-2017.)

Assertion

Ref	Expression
rhmopp	|- ( F e. ( R RingHom S ) -> F e. ( (oppr ` R ) RingHom (oppr ` S ) ) )

Proof of Theorem rhmopp

Dummy variables x y are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		eqid 2196	. 2 |- ( Base ` (oppr ` R ) ) = ( Base ` (oppr ` R ) )
2		eqid 2196	. 2 |- ( 1r ` (oppr ` R ) ) = ( 1r ` (oppr ` R ) )
3		eqid 2196	. 2 |- ( 1r ` (oppr ` S ) ) = ( 1r ` (oppr ` S ) )
4		eqid 2196	. 2 |- ( .r ` (oppr ` R ) ) = ( .r ` (oppr ` R ) )
5		eqid 2196	. 2 |- ( .r ` (oppr ` S ) ) = ( .r ` (oppr ` S ) )
6		rhmrcl1 13711	. . 3 |- ( F e. ( R RingHom S ) -> R e. Ring )
7		eqid 2196	. . . . 5 |- (oppr ` R ) = (oppr ` R )
8	7	opprringbg 13636	. . . 4 |- ( R e. Ring -> ( R e. Ring <-> (oppr ` R ) e. Ring ) )
9	6, 8	syl 14	. . 3 |- ( F e. ( R RingHom S ) -> ( R e. Ring <-> (oppr ` R ) e. Ring ) )
10	6, 9	mpbid 147	. 2 |- ( F e. ( R RingHom S ) -> (oppr ` R ) e. Ring )
11		rhmrcl2 13712	. . 3 |- ( F e. ( R RingHom S ) -> S e. Ring )
12		eqid 2196	. . . . 5 |- (oppr ` S ) = (oppr ` S )
13	12	opprringbg 13636	. . . 4 |- ( S e. Ring -> ( S e. Ring <-> (oppr ` S ) e. Ring ) )
14	11, 13	syl 14	. . 3 |- ( F e. ( R RingHom S ) -> ( S e. Ring <-> (oppr ` S ) e. Ring ) )
15	11, 14	mpbid 147	. 2 |- ( F e. ( R RingHom S ) -> (oppr ` S ) e. Ring )
16		eqid 2196	. . . 4 |- ( 1r ` R ) = ( 1r ` R )
17		eqid 2196	. . . 4 |- ( 1r ` S ) = ( 1r ` S )
18	16, 17	rhm1 13723	. . 3 |- ( F e. ( R RingHom S ) -> ( F ` ( 1r ` R ) ) = ( 1r ` S ) )
19	7, 16	oppr1g 13638	. . . . . 6 |- ( R e. Ring -> ( 1r ` R ) = ( 1r ` (oppr ` R ) ) )
20	6, 19	syl 14	. . . . 5 |- ( F e. ( R RingHom S ) -> ( 1r ` R ) = ( 1r ` (oppr ` R ) ) )
21	20	eqcomd 2202	. . . 4 |- ( F e. ( R RingHom S ) -> ( 1r ` (oppr ` R ) ) = ( 1r ` R ) )
22	21	fveq2d 5562	. . 3 |- ( F e. ( R RingHom S ) -> ( F ` ( 1r ` (oppr ` R ) ) ) = ( F ` ( 1r ` R ) ) )
23	12, 17	oppr1g 13638	. . . . 5 |- ( S e. Ring -> ( 1r ` S ) = ( 1r ` (oppr ` S ) ) )
24	11, 23	syl 14	. . . 4 |- ( F e. ( R RingHom S ) -> ( 1r ` S ) = ( 1r ` (oppr ` S ) ) )
25	24	eqcomd 2202	. . 3 |- ( F e. ( R RingHom S ) -> ( 1r ` (oppr ` S ) ) = ( 1r ` S ) )
26	18, 22, 25	3eqtr4d 2239	. 2 |- ( F e. ( R RingHom S ) -> ( F ` ( 1r ` (oppr ` R ) ) ) = ( 1r ` (oppr ` S ) ) )
27		simpl 109	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> F e. ( R RingHom S ) )
28		simprr 531	. . . . 5 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> y e. ( Base ` (oppr ` R ) ) )
29		eqid 2196	. . . . . . . 8 |- ( Base ` R ) = ( Base ` R )
30	7, 29	opprbasg 13631	. . . . . . 7 |- ( R e. Ring -> ( Base ` R ) = ( Base ` (oppr ` R ) ) )
31	6, 30	syl 14	. . . . . 6 |- ( F e. ( R RingHom S ) -> ( Base ` R ) = ( Base ` (oppr ` R ) ) )
32	27, 31	syl 14	. . . . 5 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( Base ` R ) = ( Base ` (oppr ` R ) ) )
33	28, 32	eleqtrrd 2276	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> y e. ( Base ` R ) )
34		simprl 529	. . . . 5 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> x e. ( Base ` (oppr ` R ) ) )
35	34, 32	eleqtrrd 2276	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> x e. ( Base ` R ) )
36		eqid 2196	. . . . 5 |- ( .r ` R ) = ( .r ` R )
37		eqid 2196	. . . . 5 |- ( .r ` S ) = ( .r ` S )
38	29, 36, 37	rhmmul 13720	. . . 4 |- ( ( F e. ( R RingHom S ) /\ y e. ( Base ` R ) /\ x e. ( Base ` R ) ) -> ( F ` ( y ( .r ` R ) x ) ) = ( ( F ` y ) ( .r ` S ) ( F ` x ) ) )
39	27, 33, 35, 38	syl3anc 1249	. . 3 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( F ` ( y ( .r ` R ) x ) ) = ( ( F ` y ) ( .r ` S ) ( F ` x ) ) )
40	27, 6	syl 14	. . . . 5 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> R e. Ring )
41	29, 36, 7, 4	opprmulg 13627	. . . . 5 |- ( ( R e. Ring /\ x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) -> ( x ( .r ` (oppr ` R ) ) y ) = ( y ( .r ` R ) x ) )
42	40, 34, 28, 41	syl3anc 1249	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( x ( .r ` (oppr ` R ) ) y ) = ( y ( .r ` R ) x ) )
43	42	fveq2d 5562	. . 3 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( F ` ( x ( .r ` (oppr ` R ) ) y ) ) = ( F ` ( y ( .r ` R ) x ) ) )
44	27, 11	syl 14	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> S e. Ring )
45		eqid 2196	. . . . . . 7 |- ( Base ` S ) = ( Base ` S )
46	29, 45	rhmf 13719	. . . . . 6 |- ( F e. ( R RingHom S ) -> F : ( Base ` R ) --> ( Base ` S ) )
47	27, 46	syl 14	. . . . 5 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> F : ( Base ` R ) --> ( Base ` S ) )
48	47, 35	ffvelcdmd 5698	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( F ` x ) e. ( Base ` S ) )
49	47, 33	ffvelcdmd 5698	. . . 4 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( F ` y ) e. ( Base ` S ) )
50	45, 37, 12, 5	opprmulg 13627	. . . 4 |- ( ( S e. Ring /\ ( F ` x ) e. ( Base ` S ) /\ ( F ` y ) e. ( Base ` S ) ) -> ( ( F ` x ) ( .r ` (oppr ` S ) ) ( F ` y ) ) = ( ( F ` y ) ( .r ` S ) ( F ` x ) ) )
51	44, 48, 49, 50	syl3anc 1249	. . 3 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( ( F ` x ) ( .r ` (oppr ` S ) ) ( F ` y ) ) = ( ( F ` y ) ( .r ` S ) ( F ` x ) ) )
52	39, 43, 51	3eqtr4d 2239	. 2 |- ( ( F e. ( R RingHom S ) /\ ( x e. ( Base ` (oppr ` R ) ) /\ y e. ( Base ` (oppr ` R ) ) ) ) -> ( F ` ( x ( .r ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( .r ` (oppr ` S ) ) ( F ` y ) ) )
53	10	ringgrpd 13561	. . . . 5 |- ( F e. ( R RingHom S ) -> (oppr ` R ) e. Grp )
54	15	ringgrpd 13561	. . . . 5 |- ( F e. ( R RingHom S ) -> (oppr ` S ) e. Grp )
55		rhmghm 13718	. . . . . . . . . 10 |- ( F e. ( R RingHom S ) -> F e. ( R GrpHom S ) )
56	55	ad2antrr 488	. . . . . . . . 9 |- ( ( ( F e. ( R RingHom S ) /\ x e. ( Base ` R ) ) /\ y e. ( Base ` R ) ) -> F e. ( R GrpHom S ) )
57		simplr 528	. . . . . . . . 9 |- ( ( ( F e. ( R RingHom S ) /\ x e. ( Base ` R ) ) /\ y e. ( Base ` R ) ) -> x e. ( Base ` R ) )
58		simpr 110	. . . . . . . . 9 |- ( ( ( F e. ( R RingHom S ) /\ x e. ( Base ` R ) ) /\ y e. ( Base ` R ) ) -> y e. ( Base ` R ) )
59		eqid 2196	. . . . . . . . . 10 |- ( +g ` R ) = ( +g ` R )
60		eqid 2196	. . . . . . . . . 10 |- ( +g ` S ) = ( +g ` S )
61	29, 59, 60	ghmlin 13378	. . . . . . . . 9 |- ( ( F e. ( R GrpHom S ) /\ x e. ( Base ` R ) /\ y e. ( Base ` R ) ) -> ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) )
62	56, 57, 58, 61	syl3anc 1249	. . . . . . . 8 |- ( ( ( F e. ( R RingHom S ) /\ x e. ( Base ` R ) ) /\ y e. ( Base ` R ) ) -> ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) )
63	62	ralrimiva 2570	. . . . . . 7 |- ( ( F e. ( R RingHom S ) /\ x e. ( Base ` R ) ) -> A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) )
64	63	ralrimiva 2570	. . . . . 6 |- ( F e. ( R RingHom S ) -> A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) )
65	46, 64	jca 306	. . . . 5 |- ( F e. ( R RingHom S ) -> ( F : ( Base ` R ) --> ( Base ` S ) /\ A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) ) )
66	53, 54, 65	jca31 309	. . . 4 |- ( F e. ( R RingHom S ) -> ( ( (oppr ` R ) e. Grp /\ (oppr ` S ) e. Grp ) /\ ( F : ( Base ` R ) --> ( Base ` S ) /\ A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) ) ) )
67	12, 45	opprbasg 13631	. . . . . . . 8 |- ( S e. Ring -> ( Base ` S ) = ( Base ` (oppr ` S ) ) )
68	11, 67	syl 14	. . . . . . 7 |- ( F e. ( R RingHom S ) -> ( Base ` S ) = ( Base ` (oppr ` S ) ) )
69	31, 68	feq23d 5403	. . . . . 6 |- ( F e. ( R RingHom S ) -> ( F : ( Base ` R ) --> ( Base ` S ) <-> F : ( Base ` (oppr ` R ) ) --> ( Base ` (oppr ` S ) ) ) )
70	7, 59	oppraddg 13632	. . . . . . . . . . . 12 |- ( R e. Ring -> ( +g ` R ) = ( +g ` (oppr ` R ) ) )
71	6, 70	syl 14	. . . . . . . . . . 11 |- ( F e. ( R RingHom S ) -> ( +g ` R ) = ( +g ` (oppr ` R ) ) )
72	71	oveqd 5939	. . . . . . . . . 10 |- ( F e. ( R RingHom S ) -> ( x ( +g ` R ) y ) = ( x ( +g ` (oppr ` R ) ) y ) )
73	72	fveq2d 5562	. . . . . . . . 9 |- ( F e. ( R RingHom S ) -> ( F ` ( x ( +g ` R ) y ) ) = ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) )
74	12, 60	oppraddg 13632	. . . . . . . . . . 11 |- ( S e. Ring -> ( +g ` S ) = ( +g ` (oppr ` S ) ) )
75	11, 74	syl 14	. . . . . . . . . 10 |- ( F e. ( R RingHom S ) -> ( +g ` S ) = ( +g ` (oppr ` S ) ) )
76	75	oveqd 5939	. . . . . . . . 9 |- ( F e. ( R RingHom S ) -> ( ( F ` x ) ( +g ` S ) ( F ` y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) )
77	73, 76	eqeq12d 2211	. . . . . . . 8 |- ( F e. ( R RingHom S ) -> ( ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) <-> ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) )
78	31, 77	raleqbidv 2709	. . . . . . 7 |- ( F e. ( R RingHom S ) -> ( A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) <-> A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) )
79	31, 78	raleqbidv 2709	. . . . . 6 |- ( F e. ( R RingHom S ) -> ( A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) <-> A. x e. ( Base ` (oppr ` R ) ) A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) )
80	69, 79	anbi12d 473	. . . . 5 |- ( F e. ( R RingHom S ) -> ( ( F : ( Base ` R ) --> ( Base ` S ) /\ A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) ) <-> ( F : ( Base ` (oppr ` R ) ) --> ( Base ` (oppr ` S ) ) /\ A. x e. ( Base ` (oppr ` R ) ) A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) ) )
81	80	anbi2d 464	. . . 4 |- ( F e. ( R RingHom S ) -> ( ( ( (oppr ` R ) e. Grp /\ (oppr ` S ) e. Grp ) /\ ( F : ( Base ` R ) --> ( Base ` S ) /\ A. x e. ( Base ` R ) A. y e. ( Base ` R ) ( F ` ( x ( +g ` R ) y ) ) = ( ( F ` x ) ( +g ` S ) ( F ` y ) ) ) ) <-> ( ( (oppr ` R ) e. Grp /\ (oppr ` S ) e. Grp ) /\ ( F : ( Base ` (oppr ` R ) ) --> ( Base ` (oppr ` S ) ) /\ A. x e. ( Base ` (oppr ` R ) ) A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) ) ) )
82	66, 81	mpbid 147	. . 3 |- ( F e. ( R RingHom S ) -> ( ( (oppr ` R ) e. Grp /\ (oppr ` S ) e. Grp ) /\ ( F : ( Base ` (oppr ` R ) ) --> ( Base ` (oppr ` S ) ) /\ A. x e. ( Base ` (oppr ` R ) ) A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) ) )
83		eqid 2196	. . . 4 |- ( Base ` (oppr ` S ) ) = ( Base ` (oppr ` S ) )
84		eqid 2196	. . . 4 |- ( +g ` (oppr ` R ) ) = ( +g ` (oppr ` R ) )
85		eqid 2196	. . . 4 |- ( +g ` (oppr ` S ) ) = ( +g ` (oppr ` S ) )
86	1, 83, 84, 85	isghm 13373	. . 3 |- ( F e. ( (oppr ` R ) GrpHom (oppr ` S ) ) <-> ( ( (oppr ` R ) e. Grp /\ (oppr ` S ) e. Grp ) /\ ( F : ( Base ` (oppr ` R ) ) --> ( Base ` (oppr ` S ) ) /\ A. x e. ( Base ` (oppr ` R ) ) A. y e. ( Base ` (oppr ` R ) ) ( F ` ( x ( +g ` (oppr ` R ) ) y ) ) = ( ( F ` x ) ( +g ` (oppr ` S ) ) ( F ` y ) ) ) ) )
87	82, 86	sylibr 134	. 2 |- ( F e. ( R RingHom S ) -> F e. ( (oppr ` R ) GrpHom (oppr ` S ) ) )
88	1, 2, 3, 4, 5, 10, 15, 26, 52, 87	isrhm2d 13721	1 |- ( F e. ( R RingHom S ) -> F e. ( (oppr ` R ) RingHom (oppr ` S ) ) )

Syntax hints:   -> wi 4   /\ wa 104   <-> wb 105   = wceq 1364   e. wcel 2167   A.wral 2475   -->wf 5254   ` cfv 5258  (class class class)co 5922   Basecbs 12678   +g cplusg 12755   .rcmulr 12756   Grpcgrp 13132   GrpHom cghm 13370   1rcur 13515   Ringcrg 13552  opp_rcoppr 13623   RingHom crh 13706

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 615  ax-in2 616  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-13 2169  ax-14 2170  ax-ext 2178  ax-coll 4148  ax-sep 4151  ax-nul 4159  ax-pow 4207  ax-pr 4242  ax-un 4468  ax-setind 4573  ax-cnex 7970  ax-resscn 7971  ax-1cn 7972  ax-1re 7973  ax-icn 7974  ax-addcl 7975  ax-addrcl 7976  ax-mulcl 7977  ax-addcom 7979  ax-addass 7981  ax-i2m1 7984  ax-0lt1 7985  ax-0id 7987  ax-rnegex 7988  ax-pre-ltirr 7991  ax-pre-lttrn 7993  ax-pre-ltadd 7995

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-fal 1370  df-nf 1475  df-sb 1777  df-eu 2048  df-mo 2049  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-ne 2368  df-nel 2463  df-ral 2480  df-rex 2481  df-reu 2482  df-rmo 2483  df-rab 2484  df-v 2765  df-sbc 2990  df-csb 3085  df-dif 3159  df-un 3161  df-in 3163  df-ss 3170  df-nul 3451  df-pw 3607  df-sn 3628  df-pr 3629  df-op 3631  df-uni 3840  df-int 3875  df-iun 3918  df-br 4034  df-opab 4095  df-mpt 4096  df-id 4328  df-xp 4669  df-rel 4670  df-cnv 4671  df-co 4672  df-dm 4673  df-rn 4674  df-res 4675  df-ima 4676  df-iota 5219  df-fun 5260  df-fn 5261  df-f 5262  df-f1 5263  df-fo 5264  df-f1o 5265  df-fv 5266  df-riota 5877  df-ov 5925  df-oprab 5926  df-mpo 5927  df-1st 6198  df-2nd 6199  df-tpos 6303  df-map 6709  df-pnf 8063  df-mnf 8064  df-ltxr 8066  df-inn 8991  df-2 9049  df-3 9050  df-ndx 12681  df-slot 12682  df-base 12684  df-sets 12685  df-plusg 12768  df-mulr 12769  df-0g 12929  df-mgm 12999  df-sgrp 13045  df-mnd 13058  df-mhm 13091  df-grp 13135  df-ghm 13371  df-mgp 13477  df-ur 13516  df-ring 13554  df-oppr 13624  df-rhm 13708

This theorem is referenced by:  elrhmunit  13733