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Theorem equsb3 2524
Description: Substitution applied to an atomic wff. (Contributed by Raph Levien and FL, 4-Dec-2005.) Remove dependency on ax-11 2198. (Revised by Wolf Lammen, 21-Sep-2018.)
Assertion
Ref Expression
equsb3 ([𝑥 / 𝑦]𝑦 = 𝑧𝑥 = 𝑧)
Distinct variable group:   𝑦,𝑧

Proof of Theorem equsb3
Dummy variable 𝑤 is distinct from all other variables.
StepHypRef Expression
1 sbcom3 2502 . . 3 ([𝑥 / 𝑤][𝑤 / 𝑦]𝑦 = 𝑧 ↔ [𝑥 / 𝑤][𝑥 / 𝑦]𝑦 = 𝑧)
2 equsb3lem 2523 . . . 4 ([𝑤 / 𝑦]𝑦 = 𝑧𝑤 = 𝑧)
32sbbii 2069 . . 3 ([𝑥 / 𝑤][𝑤 / 𝑦]𝑦 = 𝑧 ↔ [𝑥 / 𝑤]𝑤 = 𝑧)
4 nfv 2009 . . . 4 𝑤[𝑥 / 𝑦]𝑦 = 𝑧
54sbf 2471 . . 3 ([𝑥 / 𝑤][𝑥 / 𝑦]𝑦 = 𝑧 ↔ [𝑥 / 𝑦]𝑦 = 𝑧)
61, 3, 53bitr3i 292 . 2 ([𝑥 / 𝑤]𝑤 = 𝑧 ↔ [𝑥 / 𝑦]𝑦 = 𝑧)
7 equsb3lem 2523 . 2 ([𝑥 / 𝑤]𝑤 = 𝑧𝑥 = 𝑧)
86, 7bitr3i 268 1 ([𝑥 / 𝑦]𝑦 = 𝑧𝑥 = 𝑧)
Colors of variables: wff setvar class
Syntax hints:  wb 197  [wsb 2062
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1890  ax-4 1904  ax-5 2005  ax-6 2070  ax-7 2105  ax-10 2183  ax-12 2211  ax-13 2352
This theorem depends on definitions:  df-bi 198  df-an 385  df-or 874  df-ex 1875  df-nf 1879  df-sb 2063
This theorem is referenced by:  sb8eu  2624  mo3  2628  sb8iota  6038  mo5f  29780  mptsnunlem  33619  wl-equsb3  33763  wl-mo3t  33783  wl-sb8eut  33784  frege55lem1b  38863  sbeqal1  39272
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