MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  madebday Structured version   Visualization version   GIF version

Theorem madebday 27868
Description: A surreal is part of the set made by ordinal 𝐴 iff its birthday is less than or equal to 𝐴. Remark in [Conway] p. 29. (Contributed by Scott Fenton, 19-Aug-2024.)
Assertion
Ref Expression
madebday ((𝐴 ∈ On ∧ 𝑋 No ) → (𝑋 ∈ ( M ‘𝐴) ↔ ( bday 𝑋) ⊆ 𝐴))

Proof of Theorem madebday
Dummy variables 𝑎 𝑏 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 madebdayim 27856 . 2 (𝑋 ∈ ( M ‘𝐴) → ( bday 𝑋) ⊆ 𝐴)
2 sseq2 3990 . . . . . . 7 (𝑎 = 𝑏 → (( bday 𝑥) ⊆ 𝑎 ↔ ( bday 𝑥) ⊆ 𝑏))
3 fveq2 6881 . . . . . . . 8 (𝑎 = 𝑏 → ( M ‘𝑎) = ( M ‘𝑏))
43eleq2d 2821 . . . . . . 7 (𝑎 = 𝑏 → (𝑥 ∈ ( M ‘𝑎) ↔ 𝑥 ∈ ( M ‘𝑏)))
52, 4imbi12d 344 . . . . . 6 (𝑎 = 𝑏 → ((( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)) ↔ (( bday 𝑥) ⊆ 𝑏𝑥 ∈ ( M ‘𝑏))))
65ralbidv 3164 . . . . 5 (𝑎 = 𝑏 → (∀𝑥 No (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)) ↔ ∀𝑥 No (( bday 𝑥) ⊆ 𝑏𝑥 ∈ ( M ‘𝑏))))
7 fveq2 6881 . . . . . . . 8 (𝑥 = 𝑦 → ( bday 𝑥) = ( bday 𝑦))
87sseq1d 3995 . . . . . . 7 (𝑥 = 𝑦 → (( bday 𝑥) ⊆ 𝑏 ↔ ( bday 𝑦) ⊆ 𝑏))
9 eleq1 2823 . . . . . . 7 (𝑥 = 𝑦 → (𝑥 ∈ ( M ‘𝑏) ↔ 𝑦 ∈ ( M ‘𝑏)))
108, 9imbi12d 344 . . . . . 6 (𝑥 = 𝑦 → ((( bday 𝑥) ⊆ 𝑏𝑥 ∈ ( M ‘𝑏)) ↔ (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))))
1110cbvralvw 3224 . . . . 5 (∀𝑥 No (( bday 𝑥) ⊆ 𝑏𝑥 ∈ ( M ‘𝑏)) ↔ ∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)))
126, 11bitrdi 287 . . . 4 (𝑎 = 𝑏 → (∀𝑥 No (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)) ↔ ∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))))
13 sseq2 3990 . . . . . 6 (𝑎 = 𝐴 → (( bday 𝑥) ⊆ 𝑎 ↔ ( bday 𝑥) ⊆ 𝐴))
14 fveq2 6881 . . . . . . 7 (𝑎 = 𝐴 → ( M ‘𝑎) = ( M ‘𝐴))
1514eleq2d 2821 . . . . . 6 (𝑎 = 𝐴 → (𝑥 ∈ ( M ‘𝑎) ↔ 𝑥 ∈ ( M ‘𝐴)))
1613, 15imbi12d 344 . . . . 5 (𝑎 = 𝐴 → ((( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)) ↔ (( bday 𝑥) ⊆ 𝐴𝑥 ∈ ( M ‘𝐴))))
1716ralbidv 3164 . . . 4 (𝑎 = 𝐴 → (∀𝑥 No (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)) ↔ ∀𝑥 No (( bday 𝑥) ⊆ 𝐴𝑥 ∈ ( M ‘𝐴))))
18 bdayelon 27745 . . . . . . . . 9 ( bday 𝑥) ∈ On
19 onsseleq 6398 . . . . . . . . 9 ((( bday 𝑥) ∈ On ∧ 𝑎 ∈ On) → (( bday 𝑥) ⊆ 𝑎 ↔ (( bday 𝑥) ∈ 𝑎 ∨ ( bday 𝑥) = 𝑎)))
2018, 19mpan 690 . . . . . . . 8 (𝑎 ∈ On → (( bday 𝑥) ⊆ 𝑎 ↔ (( bday 𝑥) ∈ 𝑎 ∨ ( bday 𝑥) = 𝑎)))
2120ad2antrr 726 . . . . . . 7 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → (( bday 𝑥) ⊆ 𝑎 ↔ (( bday 𝑥) ∈ 𝑎 ∨ ( bday 𝑥) = 𝑎)))
22 simpll 766 . . . . . . . . . . 11 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → 𝑎 ∈ On)
23 onelss 6399 . . . . . . . . . . . . 13 (𝑎 ∈ On → (( bday 𝑥) ∈ 𝑎 → ( bday 𝑥) ⊆ 𝑎))
2423ad2antrr 726 . . . . . . . . . . . 12 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → (( bday 𝑥) ∈ 𝑎 → ( bday 𝑥) ⊆ 𝑎))
2524imp 406 . . . . . . . . . . 11 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → ( bday 𝑥) ⊆ 𝑎)
26 madess 27845 . . . . . . . . . . 11 ((𝑎 ∈ On ∧ ( bday 𝑥) ⊆ 𝑎) → ( M ‘( bday 𝑥)) ⊆ ( M ‘𝑎))
2722, 25, 26syl2an2r 685 . . . . . . . . . 10 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → ( M ‘( bday 𝑥)) ⊆ ( M ‘𝑎))
28 ssid 3986 . . . . . . . . . . 11 ( bday 𝑥) ⊆ ( bday 𝑥)
29 simpr 484 . . . . . . . . . . . . 13 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → ( bday 𝑥) ∈ 𝑎)
30 simplr 768 . . . . . . . . . . . . 13 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → 𝑥 No )
3129, 30jca 511 . . . . . . . . . . . 12 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → (( bday 𝑥) ∈ 𝑎𝑥 No ))
32 simpllr 775 . . . . . . . . . . . 12 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)))
33 sseq2 3990 . . . . . . . . . . . . . 14 (𝑏 = ( bday 𝑥) → (( bday 𝑦) ⊆ 𝑏 ↔ ( bday 𝑦) ⊆ ( bday 𝑥)))
34 fveq2 6881 . . . . . . . . . . . . . . 15 (𝑏 = ( bday 𝑥) → ( M ‘𝑏) = ( M ‘( bday 𝑥)))
3534eleq2d 2821 . . . . . . . . . . . . . 14 (𝑏 = ( bday 𝑥) → (𝑦 ∈ ( M ‘𝑏) ↔ 𝑦 ∈ ( M ‘( bday 𝑥))))
3633, 35imbi12d 344 . . . . . . . . . . . . 13 (𝑏 = ( bday 𝑥) → ((( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ↔ (( bday 𝑦) ⊆ ( bday 𝑥) → 𝑦 ∈ ( M ‘( bday 𝑥)))))
37 fveq2 6881 . . . . . . . . . . . . . . 15 (𝑦 = 𝑥 → ( bday 𝑦) = ( bday 𝑥))
3837sseq1d 3995 . . . . . . . . . . . . . 14 (𝑦 = 𝑥 → (( bday 𝑦) ⊆ ( bday 𝑥) ↔ ( bday 𝑥) ⊆ ( bday 𝑥)))
39 eleq1 2823 . . . . . . . . . . . . . 14 (𝑦 = 𝑥 → (𝑦 ∈ ( M ‘( bday 𝑥)) ↔ 𝑥 ∈ ( M ‘( bday 𝑥))))
4038, 39imbi12d 344 . . . . . . . . . . . . 13 (𝑦 = 𝑥 → ((( bday 𝑦) ⊆ ( bday 𝑥) → 𝑦 ∈ ( M ‘( bday 𝑥))) ↔ (( bday 𝑥) ⊆ ( bday 𝑥) → 𝑥 ∈ ( M ‘( bday 𝑥)))))
4136, 40rspc2v 3617 . . . . . . . . . . . 12 ((( bday 𝑥) ∈ 𝑎𝑥 No ) → (∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) → (( bday 𝑥) ⊆ ( bday 𝑥) → 𝑥 ∈ ( M ‘( bday 𝑥)))))
4231, 32, 41sylc 65 . . . . . . . . . . 11 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → (( bday 𝑥) ⊆ ( bday 𝑥) → 𝑥 ∈ ( M ‘( bday 𝑥))))
4328, 42mpi 20 . . . . . . . . . 10 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → 𝑥 ∈ ( M ‘( bday 𝑥)))
4427, 43sseldd 3964 . . . . . . . . 9 ((((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) ∧ ( bday 𝑥) ∈ 𝑎) → 𝑥 ∈ ( M ‘𝑎))
4544ex 412 . . . . . . . 8 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → (( bday 𝑥) ∈ 𝑎𝑥 ∈ ( M ‘𝑎)))
46 madebdaylemlrcut 27867 . . . . . . . . . . . 12 ((∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → (( L ‘𝑥) |s ( R ‘𝑥)) = 𝑥)
4718a1i 11 . . . . . . . . . . . . . 14 (𝑥 No → ( bday 𝑥) ∈ On)
48 lltropt 27841 . . . . . . . . . . . . . . 15 ( L ‘𝑥) <<s ( R ‘𝑥)
4948a1i 11 . . . . . . . . . . . . . 14 (𝑥 No → ( L ‘𝑥) <<s ( R ‘𝑥))
50 leftssold 27847 . . . . . . . . . . . . . . 15 ( L ‘𝑥) ⊆ ( O ‘( bday 𝑥))
5150a1i 11 . . . . . . . . . . . . . 14 (𝑥 No → ( L ‘𝑥) ⊆ ( O ‘( bday 𝑥)))
52 rightssold 27848 . . . . . . . . . . . . . . 15 ( R ‘𝑥) ⊆ ( O ‘( bday 𝑥))
5352a1i 11 . . . . . . . . . . . . . 14 (𝑥 No → ( R ‘𝑥) ⊆ ( O ‘( bday 𝑥)))
54 madecut 27851 . . . . . . . . . . . . . 14 (((( bday 𝑥) ∈ On ∧ ( L ‘𝑥) <<s ( R ‘𝑥)) ∧ (( L ‘𝑥) ⊆ ( O ‘( bday 𝑥)) ∧ ( R ‘𝑥) ⊆ ( O ‘( bday 𝑥)))) → (( L ‘𝑥) |s ( R ‘𝑥)) ∈ ( M ‘( bday 𝑥)))
5547, 49, 51, 53, 54syl22anc 838 . . . . . . . . . . . . 13 (𝑥 No → (( L ‘𝑥) |s ( R ‘𝑥)) ∈ ( M ‘( bday 𝑥)))
5655adantl 481 . . . . . . . . . . . 12 ((∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → (( L ‘𝑥) |s ( R ‘𝑥)) ∈ ( M ‘( bday 𝑥)))
5746, 56eqeltrrd 2836 . . . . . . . . . . 11 ((∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → 𝑥 ∈ ( M ‘( bday 𝑥)))
58 raleq 3306 . . . . . . . . . . . . 13 (( bday 𝑥) = 𝑎 → (∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ↔ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))))
5958anbi1d 631 . . . . . . . . . . . 12 (( bday 𝑥) = 𝑎 → ((∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) ↔ (∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No )))
60 fveq2 6881 . . . . . . . . . . . . 13 (( bday 𝑥) = 𝑎 → ( M ‘( bday 𝑥)) = ( M ‘𝑎))
6160eleq2d 2821 . . . . . . . . . . . 12 (( bday 𝑥) = 𝑎 → (𝑥 ∈ ( M ‘( bday 𝑥)) ↔ 𝑥 ∈ ( M ‘𝑎)))
6259, 61imbi12d 344 . . . . . . . . . . 11 (( bday 𝑥) = 𝑎 → (((∀𝑏 ∈ ( bday 𝑥)∀𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → 𝑥 ∈ ( M ‘( bday 𝑥))) ↔ ((∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → 𝑥 ∈ ( M ‘𝑎))))
6357, 62mpbii 233 . . . . . . . . . 10 (( bday 𝑥) = 𝑎 → ((∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → 𝑥 ∈ ( M ‘𝑎)))
6463com12 32 . . . . . . . . 9 ((∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) ∧ 𝑥 No ) → (( bday 𝑥) = 𝑎𝑥 ∈ ( M ‘𝑎)))
6564adantll 714 . . . . . . . 8 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → (( bday 𝑥) = 𝑎𝑥 ∈ ( M ‘𝑎)))
6645, 65jaod 859 . . . . . . 7 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → ((( bday 𝑥) ∈ 𝑎 ∨ ( bday 𝑥) = 𝑎) → 𝑥 ∈ ( M ‘𝑎)))
6721, 66sylbid 240 . . . . . 6 (((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) ∧ 𝑥 No ) → (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)))
6867ralrimiva 3133 . . . . 5 ((𝑎 ∈ On ∧ ∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏))) → ∀𝑥 No (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎)))
6968ex 412 . . . 4 (𝑎 ∈ On → (∀𝑏𝑎𝑦 No (( bday 𝑦) ⊆ 𝑏𝑦 ∈ ( M ‘𝑏)) → ∀𝑥 No (( bday 𝑥) ⊆ 𝑎𝑥 ∈ ( M ‘𝑎))))
7012, 17, 69tfis3 7858 . . 3 (𝐴 ∈ On → ∀𝑥 No (( bday 𝑥) ⊆ 𝐴𝑥 ∈ ( M ‘𝐴)))
71 fveq2 6881 . . . . . 6 (𝑥 = 𝑋 → ( bday 𝑥) = ( bday 𝑋))
7271sseq1d 3995 . . . . 5 (𝑥 = 𝑋 → (( bday 𝑥) ⊆ 𝐴 ↔ ( bday 𝑋) ⊆ 𝐴))
73 eleq1 2823 . . . . 5 (𝑥 = 𝑋 → (𝑥 ∈ ( M ‘𝐴) ↔ 𝑋 ∈ ( M ‘𝐴)))
7472, 73imbi12d 344 . . . 4 (𝑥 = 𝑋 → ((( bday 𝑥) ⊆ 𝐴𝑥 ∈ ( M ‘𝐴)) ↔ (( bday 𝑋) ⊆ 𝐴𝑋 ∈ ( M ‘𝐴))))
7574rspccva 3605 . . 3 ((∀𝑥 No (( bday 𝑥) ⊆ 𝐴𝑥 ∈ ( M ‘𝐴)) ∧ 𝑋 No ) → (( bday 𝑋) ⊆ 𝐴𝑋 ∈ ( M ‘𝐴)))
7670, 75sylan 580 . 2 ((𝐴 ∈ On ∧ 𝑋 No ) → (( bday 𝑋) ⊆ 𝐴𝑋 ∈ ( M ‘𝐴)))
771, 76impbid2 226 1 ((𝐴 ∈ On ∧ 𝑋 No ) → (𝑋 ∈ ( M ‘𝐴) ↔ ( bday 𝑋) ⊆ 𝐴))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 206  wa 395  wo 847   = wceq 1540  wcel 2109  wral 3052  wss 3931   class class class wbr 5124  Oncon0 6357  cfv 6536  (class class class)co 7410   No csur 27608   bday cbday 27610   <<s csslt 27749   |s cscut 27751   M cmade 27807   O cold 27808   L cleft 27810   R cright 27811
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-10 2142  ax-11 2158  ax-12 2178  ax-ext 2708  ax-rep 5254  ax-sep 5271  ax-nul 5281  ax-pow 5340  ax-pr 5407  ax-un 7734
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-nf 1784  df-sb 2066  df-mo 2540  df-eu 2569  df-clab 2715  df-cleq 2728  df-clel 2810  df-nfc 2886  df-ne 2934  df-ral 3053  df-rex 3062  df-rmo 3364  df-reu 3365  df-rab 3421  df-v 3466  df-sbc 3771  df-csb 3880  df-dif 3934  df-un 3936  df-in 3938  df-ss 3948  df-pss 3951  df-nul 4314  df-if 4506  df-pw 4582  df-sn 4607  df-pr 4609  df-tp 4611  df-op 4613  df-uni 4889  df-int 4928  df-iun 4974  df-br 5125  df-opab 5187  df-mpt 5207  df-tr 5235  df-id 5553  df-eprel 5558  df-po 5566  df-so 5567  df-fr 5611  df-we 5613  df-xp 5665  df-rel 5666  df-cnv 5667  df-co 5668  df-dm 5669  df-rn 5670  df-res 5671  df-ima 5672  df-pred 6295  df-ord 6360  df-on 6361  df-suc 6363  df-iota 6489  df-fun 6538  df-fn 6539  df-f 6540  df-f1 6541  df-fo 6542  df-f1o 6543  df-fv 6544  df-riota 7367  df-ov 7413  df-oprab 7414  df-mpo 7415  df-2nd 7994  df-frecs 8285  df-wrecs 8316  df-recs 8390  df-1o 8485  df-2o 8486  df-no 27611  df-slt 27612  df-bday 27613  df-sslt 27750  df-scut 27752  df-made 27812  df-old 27813  df-left 27815  df-right 27816
This theorem is referenced by:  oldbday  27869  newbday  27870  lrcut  27872  sltonold  28219
  Copyright terms: Public domain W3C validator