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Theorem iotaequ 27640
Description: Theorem *14.2 in [WhiteheadRussell] p. 189. (Contributed by Andrew Salmon, 11-Jul-2011.)
Assertion
Ref Expression
iotaequ  |-  ( iota
x x  =  y )  =  y
Distinct variable group:    x, y

Proof of Theorem iotaequ
StepHypRef Expression
1 iotaval 5232 . 2  |-  ( A. x ( x  =  y  <->  x  =  y
)  ->  ( iota x x  =  y
)  =  y )
2 biid 227 . 2  |-  ( x  =  y  <->  x  =  y )
31, 2mpg 1537 1  |-  ( iota
x x  =  y )  =  y
Colors of variables: wff set class
Syntax hints:    <-> wb 176    = wceq 1625   iotacio 5219
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1535  ax-5 1546  ax-17 1605  ax-9 1637  ax-8 1645  ax-6 1705  ax-7 1710  ax-11 1717  ax-12 1868  ax-ext 2266
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-tru 1310  df-ex 1531  df-nf 1534  df-sb 1632  df-clab 2272  df-cleq 2278  df-clel 2281  df-nfc 2410  df-rex 2551  df-v 2792  df-sbc 2994  df-un 3159  df-sn 3648  df-pr 3649  df-uni 3830  df-iota 5221
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