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Theorem kardex 8930
 Description: The collection of all sets equinumerous to a set 𝐴 and having the least possible rank is a set. This is the part of the justification of the definition of kard of [Enderton] p. 222. (Contributed by NM, 14-Dec-2003.)
Assertion
Ref Expression
kardex {𝑥 ∣ (𝑥𝐴 ∧ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦)))} ∈ V
Distinct variable group:   𝑥,𝑦,𝐴

Proof of Theorem kardex
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 df-rab 3059 . . 3 {𝑥 ∈ {𝑧𝑧𝐴} ∣ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦)} = {𝑥 ∣ (𝑥 ∈ {𝑧𝑧𝐴} ∧ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦))}
2 vex 3343 . . . . . 6 𝑥 ∈ V
3 breq1 4807 . . . . . 6 (𝑧 = 𝑥 → (𝑧𝐴𝑥𝐴))
42, 3elab 3490 . . . . 5 (𝑥 ∈ {𝑧𝑧𝐴} ↔ 𝑥𝐴)
5 breq1 4807 . . . . . 6 (𝑧 = 𝑦 → (𝑧𝐴𝑦𝐴))
65ralab 3508 . . . . 5 (∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦) ↔ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦)))
74, 6anbi12i 735 . . . 4 ((𝑥 ∈ {𝑧𝑧𝐴} ∧ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦)) ↔ (𝑥𝐴 ∧ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦))))
87abbii 2877 . . 3 {𝑥 ∣ (𝑥 ∈ {𝑧𝑧𝐴} ∧ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦))} = {𝑥 ∣ (𝑥𝐴 ∧ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦)))}
91, 8eqtri 2782 . 2 {𝑥 ∈ {𝑧𝑧𝐴} ∣ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦)} = {𝑥 ∣ (𝑥𝐴 ∧ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦)))}
10 scottex 8921 . 2 {𝑥 ∈ {𝑧𝑧𝐴} ∣ ∀𝑦 ∈ {𝑧𝑧𝐴} (rank‘𝑥) ⊆ (rank‘𝑦)} ∈ V
119, 10eqeltrri 2836 1 {𝑥 ∣ (𝑥𝐴 ∧ ∀𝑦(𝑦𝐴 → (rank‘𝑥) ⊆ (rank‘𝑦)))} ∈ V
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 383  ∀wal 1630   ∈ wcel 2139  {cab 2746  ∀wral 3050  {crab 3054  Vcvv 3340   ⊆ wss 3715   class class class wbr 4804  ‘cfv 6049   ≈ cen 8118  rankcrnk 8799 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1871  ax-4 1886  ax-5 1988  ax-6 2054  ax-7 2090  ax-8 2141  ax-9 2148  ax-10 2168  ax-11 2183  ax-12 2196  ax-13 2391  ax-ext 2740  ax-rep 4923  ax-sep 4933  ax-nul 4941  ax-pow 4992  ax-pr 5055  ax-un 7114  ax-reg 8662  ax-inf2 8711 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3or 1073  df-3an 1074  df-tru 1635  df-ex 1854  df-nf 1859  df-sb 2047  df-eu 2611  df-mo 2612  df-clab 2747  df-cleq 2753  df-clel 2756  df-nfc 2891  df-ne 2933  df-ral 3055  df-rex 3056  df-reu 3057  df-rab 3059  df-v 3342  df-sbc 3577  df-csb 3675  df-dif 3718  df-un 3720  df-in 3722  df-ss 3729  df-pss 3731  df-nul 4059  df-if 4231  df-pw 4304  df-sn 4322  df-pr 4324  df-tp 4326  df-op 4328  df-uni 4589  df-int 4628  df-iun 4674  df-br 4805  df-opab 4865  df-mpt 4882  df-tr 4905  df-id 5174  df-eprel 5179  df-po 5187  df-so 5188  df-fr 5225  df-we 5227  df-xp 5272  df-rel 5273  df-cnv 5274  df-co 5275  df-dm 5276  df-rn 5277  df-res 5278  df-ima 5279  df-pred 5841  df-ord 5887  df-on 5888  df-lim 5889  df-suc 5890  df-iota 6012  df-fun 6051  df-fn 6052  df-f 6053  df-f1 6054  df-fo 6055  df-f1o 6056  df-fv 6057  df-om 7231  df-wrecs 7576  df-recs 7637  df-rdg 7675  df-r1 8800  df-rank 8801 This theorem is referenced by: (None)
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