| Step | Hyp | Ref
| Expression |
| 1 | | etaslts 28184 |
. 2
⊢ ((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) → ∃𝑥 ∈ No
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂)) |
| 2 | | simpl1 1210 |
. . . . 5
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → 𝐴 <<s 𝐵) |
| 3 | | cutbday 28175 |
. . . . 5
⊢ (𝐴 <<s 𝐵 → (bday‘(𝐴 |s 𝐵)) = ∩ (bday “ {𝑦 ∈ No
∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)})) |
| 4 | 2, 3 | syl 18 |
. . . 4
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (bday‘(𝐴 |s 𝐵)) = ∩ (bday “ {𝑦 ∈ No
∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)})) |
| 5 | | bdayfn 28139 |
. . . . . 6
⊢ bday Fn No |
| 6 | | ssrab2 4005 |
. . . . . 6
⊢ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)} ⊆ No |
| 7 | | sneq 4590 |
. . . . . . . . 9
⊢ (𝑦 = 𝑥 → {𝑦} = {𝑥}) |
| 8 | 7 | breq2d 5114 |
. . . . . . . 8
⊢ (𝑦 = 𝑥 → (𝐴 <<s {𝑦} ↔ 𝐴 <<s {𝑥})) |
| 9 | 7 | breq1d 5112 |
. . . . . . . 8
⊢ (𝑦 = 𝑥 → ({𝑦} <<s 𝐵 ↔ {𝑥} <<s 𝐵)) |
| 10 | 8, 9 | anbi12d 644 |
. . . . . . 7
⊢ (𝑦 = 𝑥 → ((𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵) ↔ (𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵))) |
| 11 | | simprl 783 |
. . . . . . 7
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → 𝑥 ∈ No) |
| 12 | | simprr1 1240 |
. . . . . . . 8
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → 𝐴 <<s {𝑥}) |
| 13 | | simprr2 1241 |
. . . . . . . 8
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → {𝑥} <<s 𝐵) |
| 14 | 12, 13 | jca 521 |
. . . . . . 7
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵)) |
| 15 | 10, 11, 14 | elrabd 3646 |
. . . . . 6
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → 𝑥 ∈ {𝑦 ∈ No
∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)}) |
| 16 | | fnfvima 7239 |
. . . . . 6
⊢ ((bday Fn No ∧ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)} ⊆ No
∧ 𝑥 ∈ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)}) → (bday‘𝑥) ∈ (bday
“ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)})) |
| 17 | 5, 6, 15, 16 | mp3an12i 1494 |
. . . . 5
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (bday‘𝑥) ∈ (bday
“ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)})) |
| 18 | | intss1 4922 |
. . . . 5
⊢ ((bday‘𝑥) ∈ (bday
“ {𝑦 ∈ No ∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)}) → ∩
(bday “ {𝑦 ∈ No
∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)}) ⊆ (bday‘𝑥)) |
| 19 | 17, 18 | syl 18 |
. . . 4
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → ∩
(bday “ {𝑦 ∈ No
∣ (𝐴 <<s {𝑦} ∧ {𝑦} <<s 𝐵)}) ⊆ (bday‘𝑥)) |
| 20 | 4, 19 | eqsstrd 3942 |
. . 3
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (bday‘(𝐴 |s 𝐵)) ⊆ (bday‘𝑥)) |
| 21 | | simprr3 1242 |
. . 3
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (bday‘𝑥) ⊆ 𝑂) |
| 22 | 20, 21 | sstrd 3918 |
. 2
⊢ (((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) ∧ (𝑥 ∈ No ∧
(𝐴 <<s {𝑥} ∧ {𝑥} <<s 𝐵 ∧ (bday‘𝑥) ⊆ 𝑂))) → (bday‘(𝐴 |s 𝐵)) ⊆ 𝑂) |
| 23 | 1, 22 | rexlimddv 3169 |
1
⊢ ((𝐴 <<s 𝐵 ∧ 𝑂 ∈ On ∧ (bday “ (𝐴 ∪ 𝐵)) ⊆ 𝑂) → (bday‘(𝐴 |s 𝐵)) ⊆ 𝑂) |