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Theorem onsuplub 42555
Description: The supremum of a set of ordinals is the least upper bound. (Contributed by RP, 27-Jan-2025.)
Assertion
Ref Expression
onsuplub (((𝐴 ⊆ On ∧ 𝐴𝑉) ∧ 𝐵 ∈ On) → (𝐵 𝐴 ↔ ∃𝑧𝐴 𝐵𝑧))
Distinct variable groups:   𝑧,𝐴   𝑧,𝐵
Allowed substitution hint:   𝑉(𝑧)

Proof of Theorem onsuplub
StepHypRef Expression
1 eluni2 4906 . 2 (𝐵 𝐴 ↔ ∃𝑧𝐴 𝐵𝑧)
21a1i 11 1 (((𝐴 ⊆ On ∧ 𝐴𝑉) ∧ 𝐵 ∈ On) → (𝐵 𝐴 ↔ ∃𝑧𝐴 𝐵𝑧))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 205  wa 395  wcel 2098  wrex 3064  wss 3943   cuni 4902  Oncon0 6357
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-ext 2697
This theorem depends on definitions:  df-bi 206  df-an 396  df-tru 1536  df-ex 1774  df-sb 2060  df-clab 2704  df-cleq 2718  df-clel 2804  df-rex 3065  df-v 3470  df-uni 4903
This theorem is referenced by: (None)
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