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Theorem invdisj 5026
 Description: If there is a function 𝐶(𝑦) such that 𝐶(𝑦) = 𝑥 for all 𝑦 ∈ 𝐵(𝑥), then the sets 𝐵(𝑥) for distinct 𝑥 ∈ 𝐴 are disjoint. (Contributed by Mario Carneiro, 10-Dec-2016.)
Assertion
Ref Expression
invdisj (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥Disj 𝑥𝐴 𝐵)
Distinct variable groups:   𝑥,𝑦   𝑦,𝐴   𝑦,𝐵   𝑥,𝐶
Allowed substitution hints:   𝐴(𝑥)   𝐵(𝑥)   𝐶(𝑦)

Proof of Theorem invdisj
StepHypRef Expression
1 nfra2w 3216 . . 3 𝑦𝑥𝐴𝑦𝐵 𝐶 = 𝑥
2 df-ral 3135 . . . . 5 (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥 ↔ ∀𝑥(𝑥𝐴 → ∀𝑦𝐵 𝐶 = 𝑥))
3 rsp 3195 . . . . . . . . 9 (∀𝑦𝐵 𝐶 = 𝑥 → (𝑦𝐵𝐶 = 𝑥))
4 eqcom 2829 . . . . . . . . 9 (𝐶 = 𝑥𝑥 = 𝐶)
53, 4syl6ib 254 . . . . . . . 8 (∀𝑦𝐵 𝐶 = 𝑥 → (𝑦𝐵𝑥 = 𝐶))
65imim2i 16 . . . . . . 7 ((𝑥𝐴 → ∀𝑦𝐵 𝐶 = 𝑥) → (𝑥𝐴 → (𝑦𝐵𝑥 = 𝐶)))
76impd 414 . . . . . 6 ((𝑥𝐴 → ∀𝑦𝐵 𝐶 = 𝑥) → ((𝑥𝐴𝑦𝐵) → 𝑥 = 𝐶))
87alimi 1813 . . . . 5 (∀𝑥(𝑥𝐴 → ∀𝑦𝐵 𝐶 = 𝑥) → ∀𝑥((𝑥𝐴𝑦𝐵) → 𝑥 = 𝐶))
92, 8sylbi 220 . . . 4 (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥 → ∀𝑥((𝑥𝐴𝑦𝐵) → 𝑥 = 𝐶))
10 mo2icl 3680 . . . 4 (∀𝑥((𝑥𝐴𝑦𝐵) → 𝑥 = 𝐶) → ∃*𝑥(𝑥𝐴𝑦𝐵))
119, 10syl 17 . . 3 (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥 → ∃*𝑥(𝑥𝐴𝑦𝐵))
121, 11alrimi 2214 . 2 (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥 → ∀𝑦∃*𝑥(𝑥𝐴𝑦𝐵))
13 dfdisj2 5009 . 2 (Disj 𝑥𝐴 𝐵 ↔ ∀𝑦∃*𝑥(𝑥𝐴𝑦𝐵))
1412, 13sylibr 237 1 (∀𝑥𝐴𝑦𝐵 𝐶 = 𝑥Disj 𝑥𝐴 𝐵)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 399  ∀wal 1536   = wceq 1538   ∈ wcel 2114  ∃*wmo 2620  ∀wral 3130  Disj wdisj 5007 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2116  ax-9 2124  ax-10 2145  ax-11 2161  ax-12 2178  ax-ext 2794 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-mo 2622  df-clab 2801  df-cleq 2815  df-clel 2894  df-nfc 2962  df-ral 3135  df-rmo 3138  df-v 3471  df-disj 5008 This theorem is referenced by:  invdisjrabw  5027  invdisjrab  5028  ackbijnn  15174  incexc2  15184  phisum  16116  itg1addlem1  24294  musum  25774  lgsquadlem1  25962  lgsquadlem2  25963  disjabrex  30340  disjabrexf  30341  actfunsnrndisj  31950  poimirlem27  35043
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