Theorem onnobdayg 44431

Description: Every ordinal maps to a surreal number of that birthday. (Contributed by RP, 21-Sep-2023.)

Assertion

Ref	Expression
onnobdayg	⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → (bday‘(𝐴 × {𝐵})) = 𝐴)

Proof of Theorem onnobdayg

Step	Hyp	Ref	Expression
1		onnoxpg 44430	. . 3 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → (𝐴 × {𝐵}) ∈ No)
2		bdayval 28005	. . 3 ⊢ ((𝐴 × {𝐵}) ∈ No → (bday‘(𝐴 × {𝐵})) = dom (𝐴 × {𝐵}))
3	1, 2	syl 18	. 2 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → (bday‘(𝐴 × {𝐵})) = dom (𝐴 × {𝐵}))
4		simpr 490	. . 3 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → 𝐵 ∈ {1o, 2o})
5		snnzg 4734	. . 3 ⊢ (𝐵 ∈ {1o, 2o} → {𝐵} ≠ ∅)
6		dmxp 5910	. . 3 ⊢ ({𝐵} ≠ ∅ → dom (𝐴 × {𝐵}) = 𝐴)
7	4, 5, 6	3syl 19	. 2 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → dom (𝐴 × {𝐵}) = 𝐴)
8	3, 7	eqtrd 2795	1 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ {1o, 2o}) → (bday‘(𝐴 × {𝐵})) = 𝐴)

This proof depends on syntax axioms:   → wi 4   ∧ wa 401   = wceq 1569   ∈ wcel 2144   ≠ wne 2955  ∅c0 4278  {csn 4583  {cpr 4585   × cxp 5648  dom cdm 5650  Oncon0 6362  ‘cfv 6538  1_oc1o 8469  2_oc2o 8470  Nocsur 27997  bdaycbday 27999

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-8 2146  ax-9 2154  ax-10 2177  ax-11 2193  ax-12 2212  ax-ext 2732  ax-sep 5248  ax-pow 5326  ax-pr 5390  ax-un 7751

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3an 1105  df-tru 1572  df-fal 1582  df-ex 1812  df-nf 1816  df-sb 2099  df-mo 2564  df-eu 2594  df-clab 2739  df-cleq 2752  df-clel 2835  df-nfc 2909  df-ne 2956  df-ral 3077  df-rex 3087  df-rab 3413  df-v 3452  df-ss 3896  df-dif 4047  df-in 4091  df-un 4151  df-nul 4279  df-if 4482  df-pw 4558  df-sn 4584  df-pr 4586  df-op 4590  df-uni 4867  df-br 5103  df-opab 5167  df-mpt 5186  df-id 5545  df-xp 5656  df-rel 5657  df-cnv 5658  df-co 5659  df-dm 5660  df-rn 5661  df-iota 6494  df-fun 6540  df-fn 6541  df-f 6542  df-fv 6546  df-no 28000  df-bday 28002

This theorem is used by: (None)