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Theorem lubsn 17447
Description: The least upper bound of a singleton. (chsupsn 28816 analog.) (Contributed by NM, 20-Oct-2011.)
Hypotheses
Ref Expression
lubsn.b 𝐵 = (Base‘𝐾)
lubsn.u 𝑈 = (lub‘𝐾)
Assertion
Ref Expression
lubsn ((𝐾 ∈ Lat ∧ 𝑋𝐵) → (𝑈‘{𝑋}) = 𝑋)

Proof of Theorem lubsn
StepHypRef Expression
1 lubsn.u . . . 4 𝑈 = (lub‘𝐾)
2 eqid 2825 . . . 4 (join‘𝐾) = (join‘𝐾)
3 simpl 476 . . . 4 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → 𝐾 ∈ Lat)
4 simpr 479 . . . 4 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → 𝑋𝐵)
51, 2, 3, 4, 4joinval 17358 . . 3 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → (𝑋(join‘𝐾)𝑋) = (𝑈‘{𝑋, 𝑋}))
6 dfsn2 4410 . . . 4 {𝑋} = {𝑋, 𝑋}
76fveq2i 6436 . . 3 (𝑈‘{𝑋}) = (𝑈‘{𝑋, 𝑋})
85, 7syl6reqr 2880 . 2 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → (𝑈‘{𝑋}) = (𝑋(join‘𝐾)𝑋))
9 lubsn.b . . 3 𝐵 = (Base‘𝐾)
109, 2latjidm 17427 . 2 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → (𝑋(join‘𝐾)𝑋) = 𝑋)
118, 10eqtrd 2861 1 ((𝐾 ∈ Lat ∧ 𝑋𝐵) → (𝑈‘{𝑋}) = 𝑋)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 386   = wceq 1656  wcel 2164  {csn 4397  {cpr 4399  cfv 6123  (class class class)co 6905  Basecbs 16222  lubclub 17295  joincjn 17297  Latclat 17398
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1894  ax-4 1908  ax-5 2009  ax-6 2075  ax-7 2112  ax-8 2166  ax-9 2173  ax-10 2192  ax-11 2207  ax-12 2220  ax-13 2389  ax-ext 2803  ax-rep 4994  ax-sep 5005  ax-nul 5013  ax-pow 5065  ax-pr 5127  ax-un 7209
This theorem depends on definitions:  df-bi 199  df-an 387  df-or 879  df-3an 1113  df-tru 1660  df-ex 1879  df-nf 1883  df-sb 2068  df-mo 2605  df-eu 2640  df-clab 2812  df-cleq 2818  df-clel 2821  df-nfc 2958  df-ne 3000  df-ral 3122  df-rex 3123  df-reu 3124  df-rab 3126  df-v 3416  df-sbc 3663  df-csb 3758  df-dif 3801  df-un 3803  df-in 3805  df-ss 3812  df-nul 4145  df-if 4307  df-pw 4380  df-sn 4398  df-pr 4400  df-op 4404  df-uni 4659  df-iun 4742  df-br 4874  df-opab 4936  df-mpt 4953  df-id 5250  df-xp 5348  df-rel 5349  df-cnv 5350  df-co 5351  df-dm 5352  df-rn 5353  df-res 5354  df-ima 5355  df-iota 6086  df-fun 6125  df-fn 6126  df-f 6127  df-f1 6128  df-fo 6129  df-f1o 6130  df-fv 6131  df-riota 6866  df-ov 6908  df-oprab 6909  df-proset 17281  df-poset 17299  df-lub 17327  df-glb 17328  df-join 17329  df-meet 17330  df-lat 17399
This theorem is referenced by:  lubel  17475
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