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Theorem unissb 4861
Description: Relationship involving membership, subset, and union. Exercise 5 of [Enderton] p. 26 and its converse. (Contributed by NM, 20-Sep-2003.)
Assertion
Ref Expression
unissb ( 𝐴𝐵 ↔ ∀𝑥𝐴 𝑥𝐵)
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Proof of Theorem unissb
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 eluni 4833 . . . . . 6 (𝑦 𝐴 ↔ ∃𝑥(𝑦𝑥𝑥𝐴))
21imbi1i 351 . . . . 5 ((𝑦 𝐴𝑦𝐵) ↔ (∃𝑥(𝑦𝑥𝑥𝐴) → 𝑦𝐵))
3 19.23v 1934 . . . . 5 (∀𝑥((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ (∃𝑥(𝑦𝑥𝑥𝐴) → 𝑦𝐵))
42, 3bitr4i 279 . . . 4 ((𝑦 𝐴𝑦𝐵) ↔ ∀𝑥((𝑦𝑥𝑥𝐴) → 𝑦𝐵))
54albii 1811 . . 3 (∀𝑦(𝑦 𝐴𝑦𝐵) ↔ ∀𝑦𝑥((𝑦𝑥𝑥𝐴) → 𝑦𝐵))
6 alcom 2153 . . . 4 (∀𝑦𝑥((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ ∀𝑥𝑦((𝑦𝑥𝑥𝐴) → 𝑦𝐵))
7 19.21v 1931 . . . . . 6 (∀𝑦(𝑥𝐴 → (𝑦𝑥𝑦𝐵)) ↔ (𝑥𝐴 → ∀𝑦(𝑦𝑥𝑦𝐵)))
8 impexp 451 . . . . . . . 8 (((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ (𝑦𝑥 → (𝑥𝐴𝑦𝐵)))
9 bi2.04 389 . . . . . . . 8 ((𝑦𝑥 → (𝑥𝐴𝑦𝐵)) ↔ (𝑥𝐴 → (𝑦𝑥𝑦𝐵)))
108, 9bitri 276 . . . . . . 7 (((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ (𝑥𝐴 → (𝑦𝑥𝑦𝐵)))
1110albii 1811 . . . . . 6 (∀𝑦((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ ∀𝑦(𝑥𝐴 → (𝑦𝑥𝑦𝐵)))
12 dfss2 3952 . . . . . . 7 (𝑥𝐵 ↔ ∀𝑦(𝑦𝑥𝑦𝐵))
1312imbi2i 337 . . . . . 6 ((𝑥𝐴𝑥𝐵) ↔ (𝑥𝐴 → ∀𝑦(𝑦𝑥𝑦𝐵)))
147, 11, 133bitr4i 304 . . . . 5 (∀𝑦((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ (𝑥𝐴𝑥𝐵))
1514albii 1811 . . . 4 (∀𝑥𝑦((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ ∀𝑥(𝑥𝐴𝑥𝐵))
166, 15bitri 276 . . 3 (∀𝑦𝑥((𝑦𝑥𝑥𝐴) → 𝑦𝐵) ↔ ∀𝑥(𝑥𝐴𝑥𝐵))
175, 16bitri 276 . 2 (∀𝑦(𝑦 𝐴𝑦𝐵) ↔ ∀𝑥(𝑥𝐴𝑥𝐵))
18 dfss2 3952 . 2 ( 𝐴𝐵 ↔ ∀𝑦(𝑦 𝐴𝑦𝐵))
19 df-ral 3140 . 2 (∀𝑥𝐴 𝑥𝐵 ↔ ∀𝑥(𝑥𝐴𝑥𝐵))
2017, 18, 193bitr4i 304 1 ( 𝐴𝐵 ↔ ∀𝑥𝐴 𝑥𝐵)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 207  wa 396  wal 1526  wex 1771  wcel 2105  wral 3135  wss 3933   cuni 4830
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1787  ax-4 1801  ax-5 1902  ax-6 1961  ax-7 2006  ax-8 2107  ax-9 2115  ax-10 2136  ax-11 2151  ax-12 2167  ax-ext 2790
This theorem depends on definitions:  df-bi 208  df-an 397  df-or 842  df-tru 1531  df-ex 1772  df-nf 1776  df-sb 2061  df-clab 2797  df-cleq 2811  df-clel 2890  df-nfc 2960  df-ral 3140  df-v 3494  df-in 3940  df-ss 3949  df-uni 4831
This theorem is referenced by:  uniss2  4862  ssunieq  4864  sspwuni  5013  pwssb  5014  ordunisssuc  6286  sorpssuni  7447  uniordint  7510  sbthlem1  8615  ordunifi  8756  isfinite2  8764  cflim2  9673  fin23lem16  9745  fin23lem29  9751  fin1a2lem11  9820  fin1a2lem13  9822  itunitc  9831  zorng  9914  wuncval2  10157  suplem1pr  10462  suplem2pr  10463  mrcuni  16880  ipodrsfi  17761  mrelatlub  17784  subgint  18241  efgval  18772  toponmre  21629  neips  21649  neiuni  21658  alexsubALTlem2  22584  alexsubALTlem3  22585  tgpconncompeqg  22647  unidmvol  24069  tglnunirn  26261  uniinn0  30229  locfinreflem  31003  sxbrsigalem0  31428  dya2iocuni  31440  dya2iocucvr  31441  carsguni  31465  topjoin  33610  fnejoin1  33613  fnejoin2  33614  ovoliunnfl  34815  voliunnfl  34817  volsupnfl  34818  intidl  35188  unichnidl  35190  mnuunid  40490  expanduniss  40506  salexct  42494  setrec1lem2  44719  setrec2fun  44723
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