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Theorem php 8763
Description: Pigeonhole Principle. A natural number is not equinumerous to a proper subset of itself. Theorem (Pigeonhole Principle) of [Enderton] p. 134. The theorem is so-called because you can't put n + 1 pigeons into n holes (if each hole holds only one pigeon). The proof consists of lemmas phplem1 8758 through phplem4 8761, nneneq 8762, and this final piece of the proof. (Contributed by NM, 29-May-1998.)
Assertion
Ref Expression
php ((𝐴 ∈ ω ∧ 𝐵𝐴) → ¬ 𝐴𝐵)

Proof of Theorem php
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 0ss 4295 . . . . . . . 8 ∅ ⊆ 𝐵
2 sspsstr 4006 . . . . . . . 8 ((∅ ⊆ 𝐵𝐵𝐴) → ∅ ⊊ 𝐴)
31, 2mpan 690 . . . . . . 7 (𝐵𝐴 → ∅ ⊊ 𝐴)
4 0pss 4344 . . . . . . . 8 (∅ ⊊ 𝐴𝐴 ≠ ∅)
5 df-ne 2936 . . . . . . . 8 (𝐴 ≠ ∅ ↔ ¬ 𝐴 = ∅)
64, 5bitri 278 . . . . . . 7 (∅ ⊊ 𝐴 ↔ ¬ 𝐴 = ∅)
73, 6sylib 221 . . . . . 6 (𝐵𝐴 → ¬ 𝐴 = ∅)
8 nn0suc 7638 . . . . . . 7 (𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))
98orcanai 1002 . . . . . 6 ((𝐴 ∈ ω ∧ ¬ 𝐴 = ∅) → ∃𝑥 ∈ ω 𝐴 = suc 𝑥)
107, 9sylan2 596 . . . . 5 ((𝐴 ∈ ω ∧ 𝐵𝐴) → ∃𝑥 ∈ ω 𝐴 = suc 𝑥)
11 pssnel 4370 . . . . . . . . . 10 (𝐵 ⊊ suc 𝑥 → ∃𝑦(𝑦 ∈ suc 𝑥 ∧ ¬ 𝑦𝐵))
12 pssss 3996 . . . . . . . . . . . . . . . . 17 (𝐵 ⊊ suc 𝑥𝐵 ⊆ suc 𝑥)
13 ssdif 4040 . . . . . . . . . . . . . . . . . 18 (𝐵 ⊆ suc 𝑥 → (𝐵 ∖ {𝑦}) ⊆ (suc 𝑥 ∖ {𝑦}))
14 disjsn 4612 . . . . . . . . . . . . . . . . . . . 20 ((𝐵 ∩ {𝑦}) = ∅ ↔ ¬ 𝑦𝐵)
15 disj3 4353 . . . . . . . . . . . . . . . . . . . 20 ((𝐵 ∩ {𝑦}) = ∅ ↔ 𝐵 = (𝐵 ∖ {𝑦}))
1614, 15bitr3i 280 . . . . . . . . . . . . . . . . . . 19 𝑦𝐵𝐵 = (𝐵 ∖ {𝑦}))
17 sseq1 3912 . . . . . . . . . . . . . . . . . . 19 (𝐵 = (𝐵 ∖ {𝑦}) → (𝐵 ⊆ (suc 𝑥 ∖ {𝑦}) ↔ (𝐵 ∖ {𝑦}) ⊆ (suc 𝑥 ∖ {𝑦})))
1816, 17sylbi 220 . . . . . . . . . . . . . . . . . 18 𝑦𝐵 → (𝐵 ⊆ (suc 𝑥 ∖ {𝑦}) ↔ (𝐵 ∖ {𝑦}) ⊆ (suc 𝑥 ∖ {𝑦})))
1913, 18syl5ibr 249 . . . . . . . . . . . . . . . . 17 𝑦𝐵 → (𝐵 ⊆ suc 𝑥𝐵 ⊆ (suc 𝑥 ∖ {𝑦})))
20 vex 3404 . . . . . . . . . . . . . . . . . . . 20 𝑥 ∈ V
2120sucex 7557 . . . . . . . . . . . . . . . . . . 19 suc 𝑥 ∈ V
2221difexi 5206 . . . . . . . . . . . . . . . . . 18 (suc 𝑥 ∖ {𝑦}) ∈ V
23 ssdomg 8613 . . . . . . . . . . . . . . . . . 18 ((suc 𝑥 ∖ {𝑦}) ∈ V → (𝐵 ⊆ (suc 𝑥 ∖ {𝑦}) → 𝐵 ≼ (suc 𝑥 ∖ {𝑦})))
2422, 23ax-mp 5 . . . . . . . . . . . . . . . . 17 (𝐵 ⊆ (suc 𝑥 ∖ {𝑦}) → 𝐵 ≼ (suc 𝑥 ∖ {𝑦}))
2512, 19, 24syl56 36 . . . . . . . . . . . . . . . 16 𝑦𝐵 → (𝐵 ⊊ suc 𝑥𝐵 ≼ (suc 𝑥 ∖ {𝑦})))
2625imp 410 . . . . . . . . . . . . . . 15 ((¬ 𝑦𝐵𝐵 ⊊ suc 𝑥) → 𝐵 ≼ (suc 𝑥 ∖ {𝑦}))
27 vex 3404 . . . . . . . . . . . . . . . . 17 𝑦 ∈ V
2820, 27phplem3 8760 . . . . . . . . . . . . . . . 16 ((𝑥 ∈ ω ∧ 𝑦 ∈ suc 𝑥) → 𝑥 ≈ (suc 𝑥 ∖ {𝑦}))
2928ensymd 8618 . . . . . . . . . . . . . . 15 ((𝑥 ∈ ω ∧ 𝑦 ∈ suc 𝑥) → (suc 𝑥 ∖ {𝑦}) ≈ 𝑥)
30 domentr 8626 . . . . . . . . . . . . . . 15 ((𝐵 ≼ (suc 𝑥 ∖ {𝑦}) ∧ (suc 𝑥 ∖ {𝑦}) ≈ 𝑥) → 𝐵𝑥)
3126, 29, 30syl2an 599 . . . . . . . . . . . . . 14 (((¬ 𝑦𝐵𝐵 ⊊ suc 𝑥) ∧ (𝑥 ∈ ω ∧ 𝑦 ∈ suc 𝑥)) → 𝐵𝑥)
3231exp43 440 . . . . . . . . . . . . 13 𝑦𝐵 → (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → (𝑦 ∈ suc 𝑥𝐵𝑥))))
3332com4r 94 . . . . . . . . . . . 12 (𝑦 ∈ suc 𝑥 → (¬ 𝑦𝐵 → (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → 𝐵𝑥))))
3433imp 410 . . . . . . . . . . 11 ((𝑦 ∈ suc 𝑥 ∧ ¬ 𝑦𝐵) → (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → 𝐵𝑥)))
3534exlimiv 1937 . . . . . . . . . 10 (∃𝑦(𝑦 ∈ suc 𝑥 ∧ ¬ 𝑦𝐵) → (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → 𝐵𝑥)))
3611, 35mpcom 38 . . . . . . . . 9 (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → 𝐵𝑥))
37 endomtr 8625 . . . . . . . . . . . 12 ((suc 𝑥𝐵𝐵𝑥) → suc 𝑥𝑥)
38 sssucid 6259 . . . . . . . . . . . . 13 𝑥 ⊆ suc 𝑥
39 ssdomg 8613 . . . . . . . . . . . . 13 (suc 𝑥 ∈ V → (𝑥 ⊆ suc 𝑥𝑥 ≼ suc 𝑥))
4021, 38, 39mp2 9 . . . . . . . . . . . 12 𝑥 ≼ suc 𝑥
41 sbth 8699 . . . . . . . . . . . 12 ((suc 𝑥𝑥𝑥 ≼ suc 𝑥) → suc 𝑥𝑥)
4237, 40, 41sylancl 589 . . . . . . . . . . 11 ((suc 𝑥𝐵𝐵𝑥) → suc 𝑥𝑥)
4342expcom 417 . . . . . . . . . 10 (𝐵𝑥 → (suc 𝑥𝐵 → suc 𝑥𝑥))
44 peano2b 7627 . . . . . . . . . . . . 13 (𝑥 ∈ ω ↔ suc 𝑥 ∈ ω)
45 nnord 7619 . . . . . . . . . . . . 13 (suc 𝑥 ∈ ω → Ord suc 𝑥)
4644, 45sylbi 220 . . . . . . . . . . . 12 (𝑥 ∈ ω → Ord suc 𝑥)
4720sucid 6261 . . . . . . . . . . . 12 𝑥 ∈ suc 𝑥
48 nordeq 6201 . . . . . . . . . . . 12 ((Ord suc 𝑥𝑥 ∈ suc 𝑥) → suc 𝑥𝑥)
4946, 47, 48sylancl 589 . . . . . . . . . . 11 (𝑥 ∈ ω → suc 𝑥𝑥)
50 nneneq 8762 . . . . . . . . . . . . . 14 ((suc 𝑥 ∈ ω ∧ 𝑥 ∈ ω) → (suc 𝑥𝑥 ↔ suc 𝑥 = 𝑥))
5144, 50sylanb 584 . . . . . . . . . . . . 13 ((𝑥 ∈ ω ∧ 𝑥 ∈ ω) → (suc 𝑥𝑥 ↔ suc 𝑥 = 𝑥))
5251anidms 570 . . . . . . . . . . . 12 (𝑥 ∈ ω → (suc 𝑥𝑥 ↔ suc 𝑥 = 𝑥))
5352necon3bbid 2972 . . . . . . . . . . 11 (𝑥 ∈ ω → (¬ suc 𝑥𝑥 ↔ suc 𝑥𝑥))
5449, 53mpbird 260 . . . . . . . . . 10 (𝑥 ∈ ω → ¬ suc 𝑥𝑥)
5543, 54nsyli 160 . . . . . . . . 9 (𝐵𝑥 → (𝑥 ∈ ω → ¬ suc 𝑥𝐵))
5636, 55syli 39 . . . . . . . 8 (𝐵 ⊊ suc 𝑥 → (𝑥 ∈ ω → ¬ suc 𝑥𝐵))
5756com12 32 . . . . . . 7 (𝑥 ∈ ω → (𝐵 ⊊ suc 𝑥 → ¬ suc 𝑥𝐵))
58 psseq2 3989 . . . . . . . 8 (𝐴 = suc 𝑥 → (𝐵𝐴𝐵 ⊊ suc 𝑥))
59 breq1 5043 . . . . . . . . 9 (𝐴 = suc 𝑥 → (𝐴𝐵 ↔ suc 𝑥𝐵))
6059notbid 321 . . . . . . . 8 (𝐴 = suc 𝑥 → (¬ 𝐴𝐵 ↔ ¬ suc 𝑥𝐵))
6158, 60imbi12d 348 . . . . . . 7 (𝐴 = suc 𝑥 → ((𝐵𝐴 → ¬ 𝐴𝐵) ↔ (𝐵 ⊊ suc 𝑥 → ¬ suc 𝑥𝐵)))
6257, 61syl5ibrcom 250 . . . . . 6 (𝑥 ∈ ω → (𝐴 = suc 𝑥 → (𝐵𝐴 → ¬ 𝐴𝐵)))
6362rexlimiv 3191 . . . . 5 (∃𝑥 ∈ ω 𝐴 = suc 𝑥 → (𝐵𝐴 → ¬ 𝐴𝐵))
6410, 63syl 17 . . . 4 ((𝐴 ∈ ω ∧ 𝐵𝐴) → (𝐵𝐴 → ¬ 𝐴𝐵))
6564ex 416 . . 3 (𝐴 ∈ ω → (𝐵𝐴 → (𝐵𝐴 → ¬ 𝐴𝐵)))
6665pm2.43d 53 . 2 (𝐴 ∈ ω → (𝐵𝐴 → ¬ 𝐴𝐵))
6766imp 410 1 ((𝐴 ∈ ω ∧ 𝐵𝐴) → ¬ 𝐴𝐵)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 209  wa 399   = wceq 1542  wex 1786  wcel 2114  wne 2935  wrex 3055  Vcvv 3400  cdif 3850  cin 3852  wss 3853  wpss 3854  c0 4221  {csn 4526   class class class wbr 5040  Ord word 6181  suc csuc 6184  ωcom 7611  cen 8564  cdom 8565
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1802  ax-4 1816  ax-5 1917  ax-6 1975  ax-7 2020  ax-8 2116  ax-9 2124  ax-10 2145  ax-11 2162  ax-12 2179  ax-ext 2711  ax-sep 5177  ax-nul 5184  ax-pow 5242  ax-pr 5306  ax-un 7491
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 847  df-3or 1089  df-3an 1090  df-tru 1545  df-fal 1555  df-ex 1787  df-nf 1791  df-sb 2075  df-mo 2541  df-eu 2571  df-clab 2718  df-cleq 2731  df-clel 2812  df-nfc 2882  df-ne 2936  df-ral 3059  df-rex 3060  df-rab 3063  df-v 3402  df-sbc 3686  df-dif 3856  df-un 3858  df-in 3860  df-ss 3870  df-pss 3872  df-nul 4222  df-if 4425  df-pw 4500  df-sn 4527  df-pr 4529  df-tp 4531  df-op 4533  df-uni 4807  df-br 5041  df-opab 5103  df-tr 5147  df-id 5439  df-eprel 5444  df-po 5452  df-so 5453  df-fr 5493  df-we 5495  df-xp 5541  df-rel 5542  df-cnv 5543  df-co 5544  df-dm 5545  df-rn 5546  df-res 5547  df-ima 5548  df-ord 6185  df-on 6186  df-lim 6187  df-suc 6188  df-iota 6307  df-fun 6351  df-fn 6352  df-f 6353  df-f1 6354  df-fo 6355  df-f1o 6356  df-fv 6357  df-om 7612  df-er 8332  df-en 8568  df-dom 8569
This theorem is referenced by:  php2  8764  php3  8765  rr-phpd  41408
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