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Theorem hbeu 1918
 Description: Bound-variable hypothesis builder for uniqueness. Note that x and y needn't be distinct. (Contributed by NM, 8-Mar-1995.) (Proof rewritten by Jim Kingdon, 24-May-2018.)
Hypothesis
Ref Expression
hbeu.1 (φxφ)
Assertion
Ref Expression
hbeu (∃!yφx∃!yφ)

Proof of Theorem hbeu
StepHypRef Expression
1 hbeu.1 . . . 4 (φxφ)
21nfi 1348 . . 3 xφ
32nfeu 1916 . 2 x∃!yφ
43nfri 1409 1 (∃!yφx∃!yφ)
 Colors of variables: wff set class Syntax hints:   → wi 4  ∀wal 1240  ∃!weu 1897 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 629  ax-5 1333  ax-7 1334  ax-gen 1335  ax-ie1 1379  ax-ie2 1380  ax-8 1392  ax-10 1393  ax-11 1394  ax-i12 1395  ax-bnd 1396  ax-4 1397  ax-17 1416  ax-i9 1420  ax-ial 1424  ax-i5r 1425 This theorem depends on definitions:  df-bi 110  df-tru 1245  df-nf 1347  df-sb 1643  df-eu 1900 This theorem is referenced by:  hbmo  1936  2eu7  1991
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