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Theorem carden2a 9043
Description: If two sets have equal nonzero cardinalities, then they are equinumerous. (This assertion and carden2b 9044 are meant to replace carden 9626 in ZF without AC.) (Contributed by Mario Carneiro, 9-Jan-2013.)
Assertion
Ref Expression
carden2a (((card‘𝐴) = (card‘𝐵) ∧ (card‘𝐴) ≠ ∅) → 𝐴𝐵)

Proof of Theorem carden2a
StepHypRef Expression
1 df-ne 2938 . 2 ((card‘𝐴) ≠ ∅ ↔ ¬ (card‘𝐴) = ∅)
2 ndmfv 6405 . . . . . . 7 𝐵 ∈ dom card → (card‘𝐵) = ∅)
3 eqeq1 2769 . . . . . . 7 ((card‘𝐴) = (card‘𝐵) → ((card‘𝐴) = ∅ ↔ (card‘𝐵) = ∅))
42, 3syl5ibr 237 . . . . . 6 ((card‘𝐴) = (card‘𝐵) → (¬ 𝐵 ∈ dom card → (card‘𝐴) = ∅))
54con1d 141 . . . . 5 ((card‘𝐴) = (card‘𝐵) → (¬ (card‘𝐴) = ∅ → 𝐵 ∈ dom card))
65imp 395 . . . 4 (((card‘𝐴) = (card‘𝐵) ∧ ¬ (card‘𝐴) = ∅) → 𝐵 ∈ dom card)
7 cardid2 9030 . . . 4 (𝐵 ∈ dom card → (card‘𝐵) ≈ 𝐵)
86, 7syl 17 . . 3 (((card‘𝐴) = (card‘𝐵) ∧ ¬ (card‘𝐴) = ∅) → (card‘𝐵) ≈ 𝐵)
9 cardid2 9030 . . . . . . 7 (𝐴 ∈ dom card → (card‘𝐴) ≈ 𝐴)
10 ndmfv 6405 . . . . . . 7 𝐴 ∈ dom card → (card‘𝐴) = ∅)
119, 10nsyl4 157 . . . . . 6 (¬ (card‘𝐴) = ∅ → (card‘𝐴) ≈ 𝐴)
1211ensymd 8211 . . . . 5 (¬ (card‘𝐴) = ∅ → 𝐴 ≈ (card‘𝐴))
13 breq2 4813 . . . . . 6 ((card‘𝐴) = (card‘𝐵) → (𝐴 ≈ (card‘𝐴) ↔ 𝐴 ≈ (card‘𝐵)))
14 entr 8212 . . . . . . 7 ((𝐴 ≈ (card‘𝐵) ∧ (card‘𝐵) ≈ 𝐵) → 𝐴𝐵)
1514ex 401 . . . . . 6 (𝐴 ≈ (card‘𝐵) → ((card‘𝐵) ≈ 𝐵𝐴𝐵))
1613, 15syl6bi 244 . . . . 5 ((card‘𝐴) = (card‘𝐵) → (𝐴 ≈ (card‘𝐴) → ((card‘𝐵) ≈ 𝐵𝐴𝐵)))
1712, 16syl5 34 . . . 4 ((card‘𝐴) = (card‘𝐵) → (¬ (card‘𝐴) = ∅ → ((card‘𝐵) ≈ 𝐵𝐴𝐵)))
1817imp 395 . . 3 (((card‘𝐴) = (card‘𝐵) ∧ ¬ (card‘𝐴) = ∅) → ((card‘𝐵) ≈ 𝐵𝐴𝐵))
198, 18mpd 15 . 2 (((card‘𝐴) = (card‘𝐵) ∧ ¬ (card‘𝐴) = ∅) → 𝐴𝐵)
201, 19sylan2b 587 1 (((card‘𝐴) = (card‘𝐵) ∧ (card‘𝐴) ≠ ∅) → 𝐴𝐵)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 384   = wceq 1652  wcel 2155  wne 2937  c0 4079   class class class wbr 4809  dom cdm 5277  cfv 6068  cen 8157  cardccrd 9012
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1890  ax-4 1904  ax-5 2005  ax-6 2070  ax-7 2105  ax-8 2157  ax-9 2164  ax-10 2183  ax-11 2198  ax-12 2211  ax-13 2352  ax-ext 2743  ax-sep 4941  ax-nul 4949  ax-pow 5001  ax-pr 5062  ax-un 7147
This theorem depends on definitions:  df-bi 198  df-an 385  df-or 874  df-3or 1108  df-3an 1109  df-tru 1656  df-ex 1875  df-nf 1879  df-sb 2063  df-mo 2565  df-eu 2582  df-clab 2752  df-cleq 2758  df-clel 2761  df-nfc 2896  df-ne 2938  df-ral 3060  df-rex 3061  df-rab 3064  df-v 3352  df-sbc 3597  df-dif 3735  df-un 3737  df-in 3739  df-ss 3746  df-pss 3748  df-nul 4080  df-if 4244  df-pw 4317  df-sn 4335  df-pr 4337  df-tp 4339  df-op 4341  df-uni 4595  df-int 4634  df-br 4810  df-opab 4872  df-mpt 4889  df-tr 4912  df-id 5185  df-eprel 5190  df-po 5198  df-so 5199  df-fr 5236  df-we 5238  df-xp 5283  df-rel 5284  df-cnv 5285  df-co 5286  df-dm 5287  df-rn 5288  df-res 5289  df-ima 5290  df-ord 5911  df-on 5912  df-iota 6031  df-fun 6070  df-fn 6071  df-f 6072  df-f1 6073  df-fo 6074  df-f1o 6075  df-fv 6076  df-er 7947  df-en 8161  df-card 9016
This theorem is referenced by:  card1  9045
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