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Theorem sbid 2111
 Description: An identity theorem for substitution. Remark 9.1 in [Megill] p. 447 (p. 15 of the preprint). (Contributed by NM, 26-May-1993.) (Proof shortened by Wolf Lammen, 30-Sep-2018.)
Assertion
Ref Expression
sbid ([𝑥 / 𝑥]𝜑𝜑)

Proof of Theorem sbid
StepHypRef Expression
1 equid 1936 . 2 𝑥 = 𝑥
2 sbequ12r 2109 . 2 (𝑥 = 𝑥 → ([𝑥 / 𝑥]𝜑𝜑))
31, 2ax-mp 5 1 ([𝑥 / 𝑥]𝜑𝜑)
 Colors of variables: wff setvar class Syntax hints:   ↔ wb 196  [wsb 1877 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-12 2044 This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1702  df-sb 1878 This theorem is referenced by:  sbco  2411  sbidm  2413  sbal2  2460  abid  2609  sbceq1a  3433  sbcid  3439  frege58bid  37717  sbidd  41782  sbidd-misc  41783
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