Metamath Proof Explorer


Theorem nosupbday

Description: Birthday bounding law for surreal supremum. (Contributed by Scott Fenton, 5-Dec-2021)

Ref Expression
Hypothesis nosupbday.1 𝑆 = if ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 , ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) , ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) )
Assertion nosupbday ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → ( bday 𝑆 ) ⊆ 𝑂 )

Proof

Step Hyp Ref Expression
1 nosupbday.1 𝑆 = if ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 , ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) , ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) )
2 1 nosupno ( ( 𝐴 No 𝐴 ∈ V ) → 𝑆 No )
3 2 adantr ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → 𝑆 No )
4 bdayval ( 𝑆 No → ( bday 𝑆 ) = dom 𝑆 )
5 3 4 syl ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → ( bday 𝑆 ) = dom 𝑆 )
6 iftrue ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → if ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 , ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) , ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) ) = ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) )
7 1 6 syl5eq ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦𝑆 = ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) )
8 7 dmeqd ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → dom 𝑆 = dom ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) )
9 2oex 2o ∈ V
10 9 dmsnop dom { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } = { dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) }
11 10 uneq2i ( dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ dom { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) = ( dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) } )
12 dmun dom ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) = ( dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ dom { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } )
13 df-suc suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) = ( dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) } )
14 11 12 13 3eqtr4i dom ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) = suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
15 8 14 eqtrdi ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → dom 𝑆 = suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) )
16 15 adantr ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → dom 𝑆 = suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) )
17 simprrl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → 𝑂 ∈ On )
18 eloni ( 𝑂 ∈ On → Ord 𝑂 )
19 17 18 syl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → Ord 𝑂 )
20 simprll ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → 𝐴 No )
21 simpl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( 𝐴 No 𝐴 ∈ V ) ) → ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
22 nomaxmo ( 𝐴 No → ∃* 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
23 22 adantr ( ( 𝐴 No 𝐴 ∈ V ) → ∃* 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
24 23 adantl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( 𝐴 No 𝐴 ∈ V ) ) → ∃* 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
25 reu5 ( ∃! 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ↔ ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ∃* 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) )
26 21 24 25 sylanbrc ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( 𝐴 No 𝐴 ∈ V ) ) → ∃! 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
27 26 adantrr ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ∃! 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 )
28 riotacl ( ∃! 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ 𝐴 )
29 27 28 syl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ 𝐴 )
30 20 29 sseldd ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ No )
31 bdayval ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ No → ( bday ‘ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ) = dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) )
32 30 31 syl ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( bday ‘ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ) = dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) )
33 simprrr ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( bday 𝐴 ) ⊆ 𝑂 )
34 bdayfo bday : No onto→ On
35 fofn ( bday : No onto→ On → bday Fn No )
36 34 35 ax-mp bday Fn No
37 fnfvima ( ( bday Fn No 𝐴 No ∧ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ 𝐴 ) → ( bday ‘ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ) ∈ ( bday 𝐴 ) )
38 36 20 29 37 mp3an2i ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( bday ‘ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ) ∈ ( bday 𝐴 ) )
39 33 38 sseldd ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → ( bday ‘ ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ) ∈ 𝑂 )
40 32 39 eqeltrrd ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ 𝑂 )
41 ordsucss ( Ord 𝑂 → ( dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∈ 𝑂 → suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ⊆ 𝑂 ) )
42 19 40 41 sylc ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → suc dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ⊆ 𝑂 )
43 16 42 eqsstrd ( ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → dom 𝑆𝑂 )
44 iffalse ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → if ( ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 , ( ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) ∪ { ⟨ dom ( 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ) , 2o ⟩ } ) , ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) ) = ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) )
45 1 44 syl5eq ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦𝑆 = ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) )
46 45 dmeqd ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → dom 𝑆 = dom ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) )
47 iotaex ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ∈ V
48 eqid ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) = ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) )
49 47 48 dmmpti dom ( 𝑔 ∈ { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ↦ ( ℩ 𝑥𝑢𝐴 ( 𝑔 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑔 ) = ( 𝑣 ↾ suc 𝑔 ) ) ∧ ( 𝑢𝑔 ) = 𝑥 ) ) ) = { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) }
50 46 49 eqtrdi ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 → dom 𝑆 = { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } )
51 50 adantr ( ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → dom 𝑆 = { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } )
52 simplrl ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → 𝑂 ∈ On )
53 ssel2 ( ( 𝐴 No 𝑢𝐴 ) → 𝑢 No )
54 53 ad4ant14 ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → 𝑢 No )
55 bdayval ( 𝑢 No → ( bday 𝑢 ) = dom 𝑢 )
56 54 55 syl ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( bday 𝑢 ) = dom 𝑢 )
57 simplrr ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( bday 𝐴 ) ⊆ 𝑂 )
58 fnfvima ( ( bday Fn No 𝐴 No 𝑢𝐴 ) → ( bday 𝑢 ) ∈ ( bday 𝐴 ) )
59 36 58 mp3an1 ( ( 𝐴 No 𝑢𝐴 ) → ( bday 𝑢 ) ∈ ( bday 𝐴 ) )
60 59 ad4ant14 ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( bday 𝑢 ) ∈ ( bday 𝐴 ) )
61 57 60 sseldd ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( bday 𝑢 ) ∈ 𝑂 )
62 56 61 eqeltrrd ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → dom 𝑢𝑂 )
63 onelss ( 𝑂 ∈ On → ( dom 𝑢𝑂 → dom 𝑢𝑂 ) )
64 52 62 63 sylc ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → dom 𝑢𝑂 )
65 64 sseld ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( 𝑦 ∈ dom 𝑢𝑦𝑂 ) )
66 65 adantrd ( ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ∧ 𝑢𝐴 ) → ( ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) → 𝑦𝑂 ) )
67 66 rexlimdva ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → ( ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) → 𝑦𝑂 ) )
68 67 abssdv ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ⊆ 𝑂 )
69 68 adantl ( ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → { 𝑦 ∣ ∃ 𝑢𝐴 ( 𝑦 ∈ dom 𝑢 ∧ ∀ 𝑣𝐴 ( ¬ 𝑣 <s 𝑢 → ( 𝑢 ↾ suc 𝑦 ) = ( 𝑣 ↾ suc 𝑦 ) ) ) } ⊆ 𝑂 )
70 51 69 eqsstrd ( ( ¬ ∃ 𝑥𝐴𝑦𝐴 ¬ 𝑥 <s 𝑦 ∧ ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) ) → dom 𝑆𝑂 )
71 43 70 pm2.61ian ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → dom 𝑆𝑂 )
72 5 71 eqsstrd ( ( ( 𝐴 No 𝐴 ∈ V ) ∧ ( 𝑂 ∈ On ∧ ( bday 𝐴 ) ⊆ 𝑂 ) ) → ( bday 𝑆 ) ⊆ 𝑂 )