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Theorem undif3VD 38140
Description: The first equality of Exercise 13 of [TakeutiZaring] p. 22. Virtual deduction proof of undif3 3847. The following User's Proof is a Virtual Deduction proof completed automatically by the tools program completeusersproof.cmd, which invokes Mel L. O'Cat's mmj2 and Norm Megill's Metamath Proof Assistant. undif3 3847 is undif3VD 38140 without virtual deductions and was automatically derived from undif3VD 38140.
 1:: ⊢ (𝑥 ∈ (𝐴 ∪ (𝐵 ∖ 𝐶)) ↔ (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ (𝐵 ∖ 𝐶))) 2:: ⊢ (𝑥 ∈ (𝐵 ∖ 𝐶) ↔ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)) 3:2: ⊢ ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ (𝐵 ∖ 𝐶)) ↔ (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 4:1,3: ⊢ (𝑥 ∈ (𝐴 ∪ (𝐵 ∖ 𝐶)) ↔ (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 5:: ⊢ (   𝑥 ∈ 𝐴   ▶   𝑥 ∈ 𝐴   ) 6:5: ⊢ (   𝑥 ∈ 𝐴   ▶   (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵)   ) 7:5: ⊢ (   𝑥 ∈ 𝐴   ▶   (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴)   ) 8:6,7: ⊢ (   𝑥 ∈ 𝐴   ▶   ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))   ) 9:8: ⊢ (𝑥 ∈ 𝐴 → ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ ( ¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 10:: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ) 11:10: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   𝑥 ∈ 𝐵   ) 12:10: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   ¬ 𝑥 ∈ 𝐶    ) 13:11: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵)   ) 14:12: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴)   ) 15:13,14: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))   ) 16:15: ⊢ ((𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶) → ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 17:9,16: ⊢ ((𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)) → ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 18:: ⊢ (   (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶)   ) 19:18: ⊢ (   (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   𝑥 ∈ 𝐴   ) 20:18: ⊢ (   (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   ¬ 𝑥 ∈ 𝐶    ) 21:18: ⊢ (   (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))   ) 22:21: ⊢ ((𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 23:: ⊢ (   (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)   ▶   (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)   ) 24:23: ⊢ (   (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)   ▶   𝑥 ∈ 𝐴   ) 25:24: ⊢ (   (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)   ▶   (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))   ) 26:25: ⊢ ((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴) → (𝑥 ∈ 𝐴 ∨ ( 𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 27:10: ⊢ (   (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)   ▶   (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))   ) 28:27: ⊢ ((𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 29:: ⊢ (   (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)   ▶   (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)   ) 30:29: ⊢ (   (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)   ▶   𝑥 ∈ 𝐴   ) 31:30: ⊢ (   (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)   ▶   (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))   ) 32:31: ⊢ ((𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴) → (𝑥 ∈ 𝐴 ∨ ( 𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 33:22,26: ⊢ (((𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 34:28,32: ⊢ (((𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 35:33,34: ⊢ ((((𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)) ∨ ((𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴))) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 36:: ⊢ ((((𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐴)) ∨ ((𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶) ∨ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴))) ↔ ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 37:36,35: ⊢ (((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴)) → (𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶))) 38:17,37: ⊢ ((𝑥 ∈ 𝐴 ∨ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐶)) ↔ ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 39:: ⊢ (𝑥 ∈ (𝐶 ∖ 𝐴) ↔ (𝑥 ∈ 𝐶 ∧ ¬ 𝑥 ∈ 𝐴)) 40:39: ⊢ (¬ 𝑥 ∈ (𝐶 ∖ 𝐴) ↔ ¬ (𝑥 ∈ 𝐶 ∧ ¬ 𝑥 ∈ 𝐴)) 41:: ⊢ (¬ (𝑥 ∈ 𝐶 ∧ ¬ 𝑥 ∈ 𝐴) ↔ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴)) 42:40,41: ⊢ (¬ 𝑥 ∈ (𝐶 ∖ 𝐴) ↔ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴)) 43:: ⊢ (𝑥 ∈ (𝐴 ∪ 𝐵) ↔ (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵 )) 44:43,42: ⊢ ((𝑥 ∈ (𝐴 ∪ 𝐵) ∧ ¬ 𝑥 ∈ (𝐶 ∖ 𝐴) ) ↔ ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∧ 𝑥 ∈ 𝐴))) 45:: ⊢ (𝑥 ∈ ((𝐴 ∪ 𝐵) ∖ (𝐶 ∖ 𝐴)) ↔ ( 𝑥 ∈ (𝐴 ∪ 𝐵) ∧ ¬ 𝑥 ∈ (𝐶 ∖ 𝐴))) 46:45,44: ⊢ (𝑥 ∈ ((𝐴 ∪ 𝐵) ∖ (𝐶 ∖ 𝐴)) ↔ ( (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 47:4,38: ⊢ (𝑥 ∈ (𝐴 ∪ (𝐵 ∖ 𝐶)) ↔ ((𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵) ∧ (¬ 𝑥 ∈ 𝐶 ∨ 𝑥 ∈ 𝐴))) 48:46,47: ⊢ (𝑥 ∈ (𝐴 ∪ (𝐵 ∖ 𝐶)) ↔ 𝑥 ∈ ((𝐴 ∪ 𝐵) ∖ (𝐶 ∖ 𝐴))) 49:48: ⊢ ∀𝑥(𝑥 ∈ (𝐴 ∪ (𝐵 ∖ 𝐶)) ↔ 𝑥 ∈ ((𝐴 ∪ 𝐵) ∖ (𝐶 ∖ 𝐴))) qed:49: ⊢ (𝐴 ∪ (𝐵 ∖ 𝐶)) = ((𝐴 ∪ 𝐵) ∖ (𝐶 ∖ 𝐴))
(Contributed by Alan Sare, 17-Apr-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
undif3VD (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴))

Proof of Theorem undif3VD
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 elun 3715 . . . . . 6 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ (𝑥𝐴𝑥 ∈ (𝐵𝐶)))
2 eldif 3550 . . . . . . 7 (𝑥 ∈ (𝐵𝐶) ↔ (𝑥𝐵 ∧ ¬ 𝑥𝐶))
32orbi2i 540 . . . . . 6 ((𝑥𝐴𝑥 ∈ (𝐵𝐶)) ↔ (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
41, 3bitri 263 . . . . 5 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
5 idn1 37811 . . . . . . . . . 10 (   𝑥𝐴   ▶   𝑥𝐴   )
6 orc 399 . . . . . . . . . 10 (𝑥𝐴 → (𝑥𝐴𝑥𝐵))
75, 6e1a 37873 . . . . . . . . 9 (   𝑥𝐴   ▶   (𝑥𝐴𝑥𝐵)   )
8 olc 398 . . . . . . . . . 10 (𝑥𝐴 → (¬ 𝑥𝐶𝑥𝐴))
95, 8e1a 37873 . . . . . . . . 9 (   𝑥𝐴   ▶   𝑥𝐶𝑥𝐴)   )
10 pm3.2 462 . . . . . . . . 9 ((𝑥𝐴𝑥𝐵) → ((¬ 𝑥𝐶𝑥𝐴) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))))
117, 9, 10e11 37934 . . . . . . . 8 (   𝑥𝐴   ▶   ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))   )
1211in1 37808 . . . . . . 7 (𝑥𝐴 → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
13 idn1 37811 . . . . . . . . . . 11 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   )
14 simpl 472 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → 𝑥𝐵)
1513, 14e1a 37873 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   𝑥𝐵   )
16 olc 398 . . . . . . . . . 10 (𝑥𝐵 → (𝑥𝐴𝑥𝐵))
1715, 16e1a 37873 . . . . . . . . 9 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴𝑥𝐵)   )
18 simpr 476 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → ¬ 𝑥𝐶)
1913, 18e1a 37873 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶    ¬ 𝑥𝐶   )
20 orc 399 . . . . . . . . . 10 𝑥𝐶 → (¬ 𝑥𝐶𝑥𝐴))
2119, 20e1a 37873 . . . . . . . . 9 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   𝑥𝐶𝑥𝐴)   )
2217, 21, 10e11 37934 . . . . . . . 8 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))   )
2322in1 37808 . . . . . . 7 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
2412, 23jaoi 393 . . . . . 6 ((𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
25 anddi 910 . . . . . . . 8 (((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)) ↔ (((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))))
2625bicomi 213 . . . . . . 7 ((((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
27 idn1 37811 . . . . . . . . . . 11 (   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   )
28 simpl 472 . . . . . . . . . . . 12 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → 𝑥𝐴)
2928orcd 406 . . . . . . . . . . 11 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3027, 29e1a 37873 . . . . . . . . . 10 (   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
3130in1 37808 . . . . . . . . 9 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
32 idn1 37811 . . . . . . . . . . . 12 (   (𝑥𝐴𝑥𝐴)   ▶   (𝑥𝐴𝑥𝐴)   )
33 simpl 472 . . . . . . . . . . . 12 ((𝑥𝐴𝑥𝐴) → 𝑥𝐴)
3432, 33e1a 37873 . . . . . . . . . . 11 (   (𝑥𝐴𝑥𝐴)   ▶   𝑥𝐴   )
35 orc 399 . . . . . . . . . . 11 (𝑥𝐴 → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3634, 35e1a 37873 . . . . . . . . . 10 (   (𝑥𝐴𝑥𝐴)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
3736in1 37808 . . . . . . . . 9 ((𝑥𝐴𝑥𝐴) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3831, 37jaoi 393 . . . . . . . 8 (((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
39 olc 398 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4013, 39e1a 37873 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
4140in1 37808 . . . . . . . . 9 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
42 idn1 37811 . . . . . . . . . . . 12 (   (𝑥𝐵𝑥𝐴)   ▶   (𝑥𝐵𝑥𝐴)   )
43 simpr 476 . . . . . . . . . . . 12 ((𝑥𝐵𝑥𝐴) → 𝑥𝐴)
4442, 43e1a 37873 . . . . . . . . . . 11 (   (𝑥𝐵𝑥𝐴)   ▶   𝑥𝐴   )
4544, 35e1a 37873 . . . . . . . . . 10 (   (𝑥𝐵𝑥𝐴)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
4645in1 37808 . . . . . . . . 9 ((𝑥𝐵𝑥𝐴) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4741, 46jaoi 393 . . . . . . . 8 (((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4838, 47jaoi 393 . . . . . . 7 ((((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4926, 48sylbir 224 . . . . . 6 (((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
5024, 49impbii 198 . . . . 5 ((𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
514, 50bitri 263 . . . 4 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
52 eldif 3550 . . . . 5 (𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ (𝑥 ∈ (𝐴𝐵) ∧ ¬ 𝑥 ∈ (𝐶𝐴)))
53 elun 3715 . . . . . 6 (𝑥 ∈ (𝐴𝐵) ↔ (𝑥𝐴𝑥𝐵))
54 eldif 3550 . . . . . . . 8 (𝑥 ∈ (𝐶𝐴) ↔ (𝑥𝐶 ∧ ¬ 𝑥𝐴))
5554notbii 309 . . . . . . 7 𝑥 ∈ (𝐶𝐴) ↔ ¬ (𝑥𝐶 ∧ ¬ 𝑥𝐴))
56 pm4.53 512 . . . . . . 7 (¬ (𝑥𝐶 ∧ ¬ 𝑥𝐴) ↔ (¬ 𝑥𝐶𝑥𝐴))
5755, 56bitri 263 . . . . . 6 𝑥 ∈ (𝐶𝐴) ↔ (¬ 𝑥𝐶𝑥𝐴))
5853, 57anbi12i 729 . . . . 5 ((𝑥 ∈ (𝐴𝐵) ∧ ¬ 𝑥 ∈ (𝐶𝐴)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
5952, 58bitri 263 . . . 4 (𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
6051, 59bitr4i 266 . . 3 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)))
6160ax-gen 1713 . 2 𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)))
62 dfcleq 2604 . . 3 ((𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ ∀𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴))))
6362biimpri 217 . 2 (∀𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴))) → (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴)))
6461, 63e0a 38020 1 (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   ↔ wb 195   ∨ wo 382   ∧ wa 383  ∀wal 1473   = wceq 1475   ∈ wcel 1977   ∖ cdif 3537   ∪ cun 3538 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-v 3175  df-dif 3543  df-un 3545  df-vd1 37807 This theorem is referenced by: (None)
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