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Mirrors > Home > MPE Home > Th. List > symdif0 | Structured version Visualization version GIF version |
Description: Symmetric difference with the empty class. The empty class is the identity element for symmetric difference. (Contributed by Scott Fenton, 24-Apr-2012.) |
Ref | Expression |
---|---|
symdif0 | ⊢ (𝐴 △ ∅) = 𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-symdif 4272 | . 2 ⊢ (𝐴 △ ∅) = ((𝐴 ∖ ∅) ∪ (∅ ∖ 𝐴)) | |
2 | dif0 4400 | . . 3 ⊢ (𝐴 ∖ ∅) = 𝐴 | |
3 | 0dif 4428 | . . 3 ⊢ (∅ ∖ 𝐴) = ∅ | |
4 | 2, 3 | uneq12i 4189 | . 2 ⊢ ((𝐴 ∖ ∅) ∪ (∅ ∖ 𝐴)) = (𝐴 ∪ ∅) |
5 | un0 4417 | . 2 ⊢ (𝐴 ∪ ∅) = 𝐴 | |
6 | 1, 4, 5 | 3eqtri 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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