Proof of Theorem soss
| Step | Hyp | Ref
| Expression |
| 1 | | poss 2129 |
. . 3
⊢ (A
⊆ B → (R Po B →
R Po A)) |
| 2 | | ssel 1502 |
. . . . . . . 8
⊢ (A
⊆ B → (x ∈ A
→ x ∈ B)) |
| 3 | | ssel 1502 |
. . . . . . . 8
⊢ (A
⊆ B → (y ∈ A
→ y ∈ B)) |
| 4 | 2, 3 | anim12d 431 |
. . . . . . 7
⊢ (A
⊆ B → ((x ∈ A ∧
y ∈ A) → (x
∈ B ∧ y ∈ B))) |
| 5 | 4 | syl4d 28 |
. . . . . 6
⊢ (A
⊆ B → (((x ∈ B ∧
y ∈ B) → (xRy ∨ x =
y ∨ yRx)) → ((x
∈ A ∧ y ∈ A)
→ (xRy ∨ x = y ∨
yRx)))) |
| 6 | 5 | 19.20dv 946 |
. . . . 5
⊢ (A
⊆ B → (∀y((x ∈
B ∧ y ∈ B)
→ (xRy ∨ x = y ∨
yRx)) →
∀y((x ∈ A ∧
y ∈ A) → (xRy ∨ x =
y ∨ yRx)))) |
| 7 | 6 | 19.20dv 946 |
. . . 4
⊢ (A
⊆ B → (∀x∀y((x ∈
B ∧ y ∈ B)
→ (xRy ∨ x = y ∨
yRx)) →
∀x∀y((x ∈
A ∧ y ∈ A)
→ (xRy ∨ x = y ∨
yRx)))) |
| 8 | | r2al 1231 |
. . . 4
⊢ (∀x ∈ B
∀y ∈ B (xRy ∨ x = y ∨
yRx) ↔
∀x∀y((x ∈
B ∧ y ∈ B)
→ (xRy ∨ x = y ∨
yRx))) |
| 9 | | r2al 1231 |
. . . 4
⊢ (∀x ∈ A
∀y ∈ A (xRy ∨ x = y ∨
yRx) ↔
∀x∀y((x ∈
A ∧ y ∈ A)
→ (xRy ∨ x = y ∨
yRx))) |
| 10 | 7, 8, 9 | 3imtr4g 426 |
. . 3
⊢ (A
⊆ B → (∀x ∈ B
∀y ∈ B (xRy ∨ x = y ∨
yRx) →
∀x ∈ A ∀y
∈ A (xRy ∨ x =
y ∨ yRx))) |
| 11 | 1, 10 | anim12d 431 |
. 2
⊢ (A
⊆ B → ((R Po B ∧
∀x ∈ B ∀y
∈ B (xRy ∨ x =
y ∨ yRx)) → (R Po
A ∧ ∀x ∈ A
∀y ∈ A (xRy ∨ x = y ∨
yRx)))) |
| 12 | | df-so 2138 |
. 2
⊢ (R Or
B ↔ (R Po B ∧
∀x ∈ B ∀y
∈ B (xRy ∨ x =
y ∨ yRx))) |
| 13 | | df-so 2138 |
. 2
⊢ (R Or
A ↔ (R Po A ∧
∀x ∈ A ∀y
∈ A (xRy ∨ x =
y ∨ yRx))) |
| 14 | 11, 12, 13 | 3imtr4g 426 |
1
⊢ (A
⊆ B → (R Or B →
R Or A)) |