| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | gaorb.1 | . . . 4
⊢  ∼ =
{〈𝑥, 𝑦〉 ∣ ({𝑥, 𝑦} ⊆ 𝑌 ∧ ∃𝑔 ∈ 𝑋 (𝑔 ⊕ 𝑥) = 𝑦)} | 
| 2 | 1 | relopabiv 5830 | . . 3
⊢ Rel ∼ | 
| 3 | 2 | a1i 11 | . 2
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → Rel ∼ ) | 
| 4 |  | simpr 484 | . . . . 5
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → 𝑢 ∼ 𝑣) | 
| 5 | 1 | gaorb 19325 | . . . . 5
⊢ (𝑢 ∼ 𝑣 ↔ (𝑢 ∈ 𝑌 ∧ 𝑣 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣)) | 
| 6 | 4, 5 | sylib 218 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → (𝑢 ∈ 𝑌 ∧ 𝑣 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣)) | 
| 7 | 6 | simp2d 1144 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → 𝑣 ∈ 𝑌) | 
| 8 | 6 | simp1d 1143 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → 𝑢 ∈ 𝑌) | 
| 9 | 6 | simp3d 1145 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣) | 
| 10 |  | simpll 767 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ⊕ ∈ (𝐺 GrpAct 𝑌)) | 
| 11 |  | simpr 484 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ℎ ∈ 𝑋) | 
| 12 | 8 | adantr 480 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → 𝑢 ∈ 𝑌) | 
| 13 | 7 | adantr 480 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → 𝑣 ∈ 𝑌) | 
| 14 |  | gaorber.2 | . . . . . . . 8
⊢ 𝑋 = (Base‘𝐺) | 
| 15 |  | eqid 2737 | . . . . . . . 8
⊢
(invg‘𝐺) = (invg‘𝐺) | 
| 16 | 14, 15 | gacan 19323 | . . . . . . 7
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (ℎ ∈ 𝑋 ∧ 𝑢 ∈ 𝑌 ∧ 𝑣 ∈ 𝑌)) → ((ℎ ⊕ 𝑢) = 𝑣 ↔ (((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢)) | 
| 17 | 10, 11, 12, 13, 16 | syl13anc 1374 | . . . . . 6
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ((ℎ ⊕ 𝑢) = 𝑣 ↔ (((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢)) | 
| 18 |  | gagrp 19310 | . . . . . . . . 9
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → 𝐺 ∈ Grp) | 
| 19 | 18 | adantr 480 | . . . . . . . 8
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → 𝐺 ∈ Grp) | 
| 20 | 14, 15 | grpinvcl 19005 | . . . . . . . 8
⊢ ((𝐺 ∈ Grp ∧ ℎ ∈ 𝑋) → ((invg‘𝐺)‘ℎ) ∈ 𝑋) | 
| 21 | 19, 20 | sylan 580 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ((invg‘𝐺)‘ℎ) ∈ 𝑋) | 
| 22 |  | oveq1 7438 | . . . . . . . . . 10
⊢ (𝑘 = ((invg‘𝐺)‘ℎ) → (𝑘 ⊕ 𝑣) = (((invg‘𝐺)‘ℎ) ⊕ 𝑣)) | 
| 23 | 22 | eqeq1d 2739 | . . . . . . . . 9
⊢ (𝑘 = ((invg‘𝐺)‘ℎ) → ((𝑘 ⊕ 𝑣) = 𝑢 ↔ (((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢)) | 
| 24 | 23 | rspcev 3622 | . . . . . . . 8
⊢
((((invg‘𝐺)‘ℎ) ∈ 𝑋 ∧ (((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢) → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢) | 
| 25 | 24 | ex 412 | . . . . . . 7
⊢
(((invg‘𝐺)‘ℎ) ∈ 𝑋 → ((((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢 → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢)) | 
| 26 | 21, 25 | syl 17 | . . . . . 6
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ((((invg‘𝐺)‘ℎ) ⊕ 𝑣) = 𝑢 → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢)) | 
| 27 | 17, 26 | sylbid 240 | . . . . 5
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) ∧ ℎ ∈ 𝑋) → ((ℎ ⊕ 𝑢) = 𝑣 → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢)) | 
| 28 | 27 | rexlimdva 3155 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → (∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣 → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢)) | 
| 29 | 9, 28 | mpd 15 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢) | 
| 30 | 1 | gaorb 19325 | . . 3
⊢ (𝑣 ∼ 𝑢 ↔ (𝑣 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌 ∧ ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑢)) | 
| 31 | 7, 8, 29, 30 | syl3anbrc 1344 | . 2
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∼ 𝑣) → 𝑣 ∼ 𝑢) | 
| 32 | 8 | adantrr 717 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → 𝑢 ∈ 𝑌) | 
| 33 |  | simprr 773 | . . . . 5
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → 𝑣 ∼ 𝑤) | 
| 34 | 1 | gaorb 19325 | . . . . 5
⊢ (𝑣 ∼ 𝑤 ↔ (𝑣 ∈ 𝑌 ∧ 𝑤 ∈ 𝑌 ∧ ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑤)) | 
| 35 | 33, 34 | sylib 218 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → (𝑣 ∈ 𝑌 ∧ 𝑤 ∈ 𝑌 ∧ ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑤)) | 
| 36 | 35 | simp2d 1144 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → 𝑤 ∈ 𝑌) | 
| 37 | 9 | adantrr 717 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣) | 
| 38 | 35 | simp3d 1145 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑤) | 
| 39 |  | reeanv 3229 | . . . . 5
⊢
(∃ℎ ∈
𝑋 ∃𝑘 ∈ 𝑋 ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤) ↔ (∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣 ∧ ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑤)) | 
| 40 | 18 | ad2antrr 726 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → 𝐺 ∈ Grp) | 
| 41 |  | simprlr 780 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → 𝑘 ∈ 𝑋) | 
| 42 |  | simprll 779 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → ℎ ∈ 𝑋) | 
| 43 |  | eqid 2737 | . . . . . . . . . 10
⊢
(+g‘𝐺) = (+g‘𝐺) | 
| 44 | 14, 43 | grpcl 18959 | . . . . . . . . 9
⊢ ((𝐺 ∈ Grp ∧ 𝑘 ∈ 𝑋 ∧ ℎ ∈ 𝑋) → (𝑘(+g‘𝐺)ℎ) ∈ 𝑋) | 
| 45 | 40, 41, 42, 44 | syl3anc 1373 | . . . . . . . 8
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → (𝑘(+g‘𝐺)ℎ) ∈ 𝑋) | 
| 46 |  | simpll 767 | . . . . . . . . . 10
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → ⊕ ∈ (𝐺 GrpAct 𝑌)) | 
| 47 | 32 | adantr 480 | . . . . . . . . . 10
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → 𝑢 ∈ 𝑌) | 
| 48 | 14, 43 | gaass 19315 | . . . . . . . . . 10
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑘 ∈ 𝑋 ∧ ℎ ∈ 𝑋 ∧ 𝑢 ∈ 𝑌)) → ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢) = (𝑘 ⊕ (ℎ ⊕ 𝑢))) | 
| 49 | 46, 41, 42, 47, 48 | syl13anc 1374 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢) = (𝑘 ⊕ (ℎ ⊕ 𝑢))) | 
| 50 |  | simprrl 781 | . . . . . . . . . 10
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → (ℎ ⊕ 𝑢) = 𝑣) | 
| 51 | 50 | oveq2d 7447 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → (𝑘 ⊕ (ℎ ⊕ 𝑢)) = (𝑘 ⊕ 𝑣)) | 
| 52 |  | simprrr 782 | . . . . . . . . 9
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → (𝑘 ⊕ 𝑣) = 𝑤) | 
| 53 | 49, 51, 52 | 3eqtrd 2781 | . . . . . . . 8
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢) = 𝑤) | 
| 54 |  | oveq1 7438 | . . . . . . . . . 10
⊢ (𝑓 = (𝑘(+g‘𝐺)ℎ) → (𝑓 ⊕ 𝑢) = ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢)) | 
| 55 | 54 | eqeq1d 2739 | . . . . . . . . 9
⊢ (𝑓 = (𝑘(+g‘𝐺)ℎ) → ((𝑓 ⊕ 𝑢) = 𝑤 ↔ ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢) = 𝑤)) | 
| 56 | 55 | rspcev 3622 | . . . . . . . 8
⊢ (((𝑘(+g‘𝐺)ℎ) ∈ 𝑋 ∧ ((𝑘(+g‘𝐺)ℎ) ⊕ 𝑢) = 𝑤) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤) | 
| 57 | 45, 53, 56 | syl2anc 584 | . . . . . . 7
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ ((ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋) ∧ ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤))) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤) | 
| 58 | 57 | expr 456 | . . . . . 6
⊢ ((( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) ∧ (ℎ ∈ 𝑋 ∧ 𝑘 ∈ 𝑋)) → (((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤)) | 
| 59 | 58 | rexlimdvva 3213 | . . . . 5
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → (∃ℎ ∈ 𝑋 ∃𝑘 ∈ 𝑋 ((ℎ ⊕ 𝑢) = 𝑣 ∧ (𝑘 ⊕ 𝑣) = 𝑤) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤)) | 
| 60 | 39, 59 | biimtrrid 243 | . . . 4
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → ((∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑣 ∧ ∃𝑘 ∈ 𝑋 (𝑘 ⊕ 𝑣) = 𝑤) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤)) | 
| 61 | 37, 38, 60 | mp2and 699 | . . 3
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤) | 
| 62 | 1 | gaorb 19325 | . . 3
⊢ (𝑢 ∼ 𝑤 ↔ (𝑢 ∈ 𝑌 ∧ 𝑤 ∈ 𝑌 ∧ ∃𝑓 ∈ 𝑋 (𝑓 ⊕ 𝑢) = 𝑤)) | 
| 63 | 32, 36, 61, 62 | syl3anbrc 1344 | . 2
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ (𝑢 ∼ 𝑣 ∧ 𝑣 ∼ 𝑤)) → 𝑢 ∼ 𝑤) | 
| 64 | 18 | adantr 480 | . . . . . . . 8
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∈ 𝑌) → 𝐺 ∈ Grp) | 
| 65 |  | eqid 2737 | . . . . . . . . 9
⊢
(0g‘𝐺) = (0g‘𝐺) | 
| 66 | 14, 65 | grpidcl 18983 | . . . . . . . 8
⊢ (𝐺 ∈ Grp →
(0g‘𝐺)
∈ 𝑋) | 
| 67 | 64, 66 | syl 17 | . . . . . . 7
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∈ 𝑌) → (0g‘𝐺) ∈ 𝑋) | 
| 68 | 65 | gagrpid 19312 | . . . . . . 7
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∈ 𝑌) → ((0g‘𝐺) ⊕ 𝑢) = 𝑢) | 
| 69 |  | oveq1 7438 | . . . . . . . . 9
⊢ (ℎ = (0g‘𝐺) → (ℎ ⊕ 𝑢) = ((0g‘𝐺) ⊕ 𝑢)) | 
| 70 | 69 | eqeq1d 2739 | . . . . . . . 8
⊢ (ℎ = (0g‘𝐺) → ((ℎ ⊕ 𝑢) = 𝑢 ↔ ((0g‘𝐺) ⊕ 𝑢) = 𝑢)) | 
| 71 | 70 | rspcev 3622 | . . . . . . 7
⊢
(((0g‘𝐺) ∈ 𝑋 ∧ ((0g‘𝐺) ⊕ 𝑢) = 𝑢) → ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢) | 
| 72 | 67, 68, 71 | syl2anc 584 | . . . . . 6
⊢ (( ⊕ ∈
(𝐺 GrpAct 𝑌) ∧ 𝑢 ∈ 𝑌) → ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢) | 
| 73 | 72 | ex 412 | . . . . 5
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → (𝑢 ∈ 𝑌 → ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢)) | 
| 74 | 73 | pm4.71rd 562 | . . . 4
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → (𝑢 ∈ 𝑌 ↔ (∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢 ∧ 𝑢 ∈ 𝑌))) | 
| 75 |  | df-3an 1089 | . . . . 5
⊢ ((𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢) ↔ ((𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌) ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢)) | 
| 76 |  | anidm 564 | . . . . . 6
⊢ ((𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌) ↔ 𝑢 ∈ 𝑌) | 
| 77 | 76 | anbi2ci 625 | . . . . 5
⊢ (((𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌) ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢) ↔ (∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢 ∧ 𝑢 ∈ 𝑌)) | 
| 78 | 75, 77 | bitri 275 | . . . 4
⊢ ((𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢) ↔ (∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢 ∧ 𝑢 ∈ 𝑌)) | 
| 79 | 74, 78 | bitr4di 289 | . . 3
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → (𝑢 ∈ 𝑌 ↔ (𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢))) | 
| 80 | 1 | gaorb 19325 | . . 3
⊢ (𝑢 ∼ 𝑢 ↔ (𝑢 ∈ 𝑌 ∧ 𝑢 ∈ 𝑌 ∧ ∃ℎ ∈ 𝑋 (ℎ ⊕ 𝑢) = 𝑢)) | 
| 81 | 79, 80 | bitr4di 289 | . 2
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → (𝑢 ∈ 𝑌 ↔ 𝑢 ∼ 𝑢)) | 
| 82 | 3, 31, 63, 81 | iserd 8771 | 1
⊢ ( ⊕ ∈
(𝐺 GrpAct 𝑌) → ∼ Er 𝑌) |