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Theorem symdif0 5108
Description: Symmetric difference with the empty class. The empty class is the identity element for symmetric difference. (Contributed by Scott Fenton, 24-Apr-2012.)
Assertion
Ref Expression
symdif0 (𝐴 △ ∅) = 𝐴

Proof of Theorem symdif0
StepHypRef Expression
1 df-symdif 4272 . 2 (𝐴 △ ∅) = ((𝐴 ∖ ∅) ∪ (∅ ∖ 𝐴))
2 dif0 4400 . . 3 (𝐴 ∖ ∅) = 𝐴
3 0dif 4428 . . 3 (∅ ∖ 𝐴) = ∅
42, 3uneq12i 4189 . 2 ((𝐴 ∖ ∅) ∪ (∅ ∖ 𝐴)) = (𝐴 ∪ ∅)
5 un0 4417 . 2 (𝐴 ∪ ∅) = 𝐴
61, 4, 53eqtri 2772 1 (𝐴 △ ∅) = 𝐴
Colors of variables: wff setvar class
Syntax hints:   = wceq 1537  cdif 3973  cun 3974  csymdif 4271  c0 4352
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-ext 2711
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-tru 1540  df-fal 1550  df-ex 1778  df-sb 2065  df-clab 2718  df-cleq 2732  df-clel 2819  df-rab 3444  df-v 3490  df-dif 3979  df-un 3981  df-ss 3993  df-symdif 4272  df-nul 4353
This theorem is referenced by: (None)
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