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Theorem sbeqal1 38418
 Description: If 𝑥 = 𝑦 always implies 𝑥 = 𝑧, then 𝑦 = 𝑧 is true. (Contributed by Andrew Salmon, 2-Jun-2011.)
Assertion
Ref Expression
sbeqal1 (∀𝑥(𝑥 = 𝑦𝑥 = 𝑧) → 𝑦 = 𝑧)
Distinct variable group:   𝑥,𝑧

Proof of Theorem sbeqal1
StepHypRef Expression
1 sb2 2350 . 2 (∀𝑥(𝑥 = 𝑦𝑥 = 𝑧) → [𝑦 / 𝑥]𝑥 = 𝑧)
2 equsb3 2430 . 2 ([𝑦 / 𝑥]𝑥 = 𝑧𝑦 = 𝑧)
31, 2sylib 208 1 (∀𝑥(𝑥 = 𝑦𝑥 = 𝑧) → 𝑦 = 𝑧)
 Colors of variables: wff setvar class Syntax hints:   → wi 4  ∀wal 1479  [wsb 1878 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1720  ax-4 1735  ax-5 1837  ax-6 1886  ax-7 1933  ax-10 2017  ax-12 2045  ax-13 2244 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-ex 1703  df-nf 1708  df-sb 1879 This theorem is referenced by:  sbeqal1i  38419  sbeqalbi  38421
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