| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | disjrel 38732 | . . . . . . . 8
⊢ ( Disj
𝑅 → Rel 𝑅) | 
| 2 |  | releldmqscoss 38662 | . . . . . . . . 9
⊢ (𝑣 ∈ V → (Rel 𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) ↔ ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅))) | 
| 3 | 2 | elv 3484 | . . . . . . . 8
⊢ (Rel
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) ↔ ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅)) | 
| 4 | 1, 3 | syl 17 | . . . . . . 7
⊢ ( Disj
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) ↔ ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅)) | 
| 5 |  | disjlem19 38803 | . . . . . . . . . 10
⊢ (𝑥 ∈ V → ( Disj 𝑅 → ((𝑢 ∈ dom 𝑅 ∧ 𝑥 ∈ [𝑢]𝑅) → [𝑢]𝑅 = [𝑥] ≀ 𝑅))) | 
| 6 | 5 | elv 3484 | . . . . . . . . 9
⊢ ( Disj
𝑅 → ((𝑢 ∈ dom 𝑅 ∧ 𝑥 ∈ [𝑢]𝑅) → [𝑢]𝑅 = [𝑥] ≀ 𝑅)) | 
| 7 | 6 | ralrimivv 3199 | . . . . . . . 8
⊢ ( Disj
𝑅 → ∀𝑢 ∈ dom 𝑅∀𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = [𝑥] ≀ 𝑅) | 
| 8 |  | 2r19.29 3138 | . . . . . . . . 9
⊢
((∀𝑢 ∈
dom 𝑅∀𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅)) | 
| 9 | 8 | ex 412 | . . . . . . . 8
⊢
(∀𝑢 ∈
dom 𝑅∀𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = [𝑥] ≀ 𝑅 → (∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅 → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅))) | 
| 10 | 7, 9 | syl 17 | . . . . . . 7
⊢ ( Disj
𝑅 → (∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅𝑣 = [𝑥] ≀ 𝑅 → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅))) | 
| 11 | 4, 10 | sylbid 240 | . . . . . 6
⊢ ( Disj
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅))) | 
| 12 |  | eqtr3 2762 | . . . . . . . 8
⊢ (([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅) → [𝑢]𝑅 = 𝑣) | 
| 13 | 12 | reximi 3083 | . . . . . . 7
⊢
(∃𝑥 ∈ [
𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅) → ∃𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = 𝑣) | 
| 14 | 13 | reximi 3083 | . . . . . 6
⊢
(∃𝑢 ∈ dom
𝑅∃𝑥 ∈ [ 𝑢]𝑅([𝑢]𝑅 = [𝑥] ≀ 𝑅 ∧ 𝑣 = [𝑥] ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = 𝑣) | 
| 15 | 11, 14 | syl6 35 | . . . . 5
⊢ ( Disj
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅∃𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = 𝑣)) | 
| 16 |  | df-rex 3070 | . . . . . . . 8
⊢
(∃𝑥 ∈ [
𝑢]𝑅[𝑢]𝑅 = 𝑣 ↔ ∃𝑥(𝑥 ∈ [𝑢]𝑅 ∧ [𝑢]𝑅 = 𝑣)) | 
| 17 |  | 19.41v 1948 | . . . . . . . 8
⊢
(∃𝑥(𝑥 ∈ [𝑢]𝑅 ∧ [𝑢]𝑅 = 𝑣) ↔ (∃𝑥 𝑥 ∈ [𝑢]𝑅 ∧ [𝑢]𝑅 = 𝑣)) | 
| 18 | 16, 17 | bitri 275 | . . . . . . 7
⊢
(∃𝑥 ∈ [
𝑢]𝑅[𝑢]𝑅 = 𝑣 ↔ (∃𝑥 𝑥 ∈ [𝑢]𝑅 ∧ [𝑢]𝑅 = 𝑣)) | 
| 19 | 18 | simprbi 496 | . . . . . 6
⊢
(∃𝑥 ∈ [
𝑢]𝑅[𝑢]𝑅 = 𝑣 → [𝑢]𝑅 = 𝑣) | 
| 20 | 19 | reximi 3083 | . . . . 5
⊢
(∃𝑢 ∈ dom
𝑅∃𝑥 ∈ [ 𝑢]𝑅[𝑢]𝑅 = 𝑣 → ∃𝑢 ∈ dom 𝑅[𝑢]𝑅 = 𝑣) | 
| 21 | 15, 20 | syl6 35 | . . . 4
⊢ ( Disj
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅[𝑢]𝑅 = 𝑣)) | 
| 22 |  | eqcom 2743 | . . . . 5
⊢ ([𝑢]𝑅 = 𝑣 ↔ 𝑣 = [𝑢]𝑅) | 
| 23 | 22 | rexbii 3093 | . . . 4
⊢
(∃𝑢 ∈ dom
𝑅[𝑢]𝑅 = 𝑣 ↔ ∃𝑢 ∈ dom 𝑅 𝑣 = [𝑢]𝑅) | 
| 24 | 21, 23 | imbitrdi 251 | . . 3
⊢ ( Disj
𝑅 → (𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅) → ∃𝑢 ∈ dom 𝑅 𝑣 = [𝑢]𝑅)) | 
| 25 | 24 | ss2abdv 4065 | . 2
⊢ ( Disj
𝑅 → {𝑣 ∣ 𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅)} ⊆ {𝑣 ∣ ∃𝑢 ∈ dom 𝑅 𝑣 = [𝑢]𝑅}) | 
| 26 |  | abid1 2877 | . 2
⊢ (dom
≀ 𝑅 / ≀
𝑅) = {𝑣 ∣ 𝑣 ∈ (dom ≀ 𝑅 / ≀ 𝑅)} | 
| 27 |  | df-qs 8752 | . 2
⊢ (dom
𝑅 / 𝑅) = {𝑣 ∣ ∃𝑢 ∈ dom 𝑅 𝑣 = [𝑢]𝑅} | 
| 28 | 25, 26, 27 | 3sstr4g 4036 | 1
⊢ ( Disj
𝑅 → (dom ≀ 𝑅 / ≀ 𝑅) ⊆ (dom 𝑅 / 𝑅)) |