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Theorem undif3VD 41759
Description: The first equality of Exercise 13 of [TakeutiZaring] p. 22. Virtual deduction proof of undif3 4218. 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 4218 is undif3VD 41759 without virtual deductions and was automatically derived from undif3VD 41759.
 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 4079 . . . . . 6 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ (𝑥𝐴𝑥 ∈ (𝐵𝐶)))
2 eldif 3893 . . . . . . 7 (𝑥 ∈ (𝐵𝐶) ↔ (𝑥𝐵 ∧ ¬ 𝑥𝐶))
32orbi2i 910 . . . . . 6 ((𝑥𝐴𝑥 ∈ (𝐵𝐶)) ↔ (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
41, 3bitri 278 . . . . 5 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
5 idn1 41451 . . . . . . . . . 10 (   𝑥𝐴   ▶   𝑥𝐴   )
6 orc 864 . . . . . . . . . 10 (𝑥𝐴 → (𝑥𝐴𝑥𝐵))
75, 6e1a 41504 . . . . . . . . 9 (   𝑥𝐴   ▶   (𝑥𝐴𝑥𝐵)   )
8 olc 865 . . . . . . . . . 10 (𝑥𝐴 → (¬ 𝑥𝐶𝑥𝐴))
95, 8e1a 41504 . . . . . . . . 9 (   𝑥𝐴   ▶   𝑥𝐶𝑥𝐴)   )
10 pm3.2 473 . . . . . . . . 9 ((𝑥𝐴𝑥𝐵) → ((¬ 𝑥𝐶𝑥𝐴) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))))
117, 9, 10e11 41565 . . . . . . . 8 (   𝑥𝐴   ▶   ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))   )
1211in1 41448 . . . . . . 7 (𝑥𝐴 → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
13 idn1 41451 . . . . . . . . . . 11 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   )
14 simpl 486 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → 𝑥𝐵)
1513, 14e1a 41504 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   𝑥𝐵   )
16 olc 865 . . . . . . . . . 10 (𝑥𝐵 → (𝑥𝐴𝑥𝐵))
1715, 16e1a 41504 . . . . . . . . 9 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴𝑥𝐵)   )
18 simpr 488 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → ¬ 𝑥𝐶)
1913, 18e1a 41504 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶    ¬ 𝑥𝐶   )
20 orc 864 . . . . . . . . . 10 𝑥𝐶 → (¬ 𝑥𝐶𝑥𝐴))
2119, 20e1a 41504 . . . . . . . . 9 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   𝑥𝐶𝑥𝐴)   )
2217, 21, 10e11 41565 . . . . . . . 8 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴))   )
2322in1 41448 . . . . . . 7 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
2412, 23jaoi 854 . . . . . 6 ((𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)) → ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
25 anddi 1008 . . . . . . . 8 (((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)) ↔ (((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))))
2625bicomi 227 . . . . . . 7 ((((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
27 idn1 41451 . . . . . . . . . . 11 (   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   )
28 simpl 486 . . . . . . . . . . . 12 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → 𝑥𝐴)
2928orcd 870 . . . . . . . . . . 11 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3027, 29e1a 41504 . . . . . . . . . 10 (   (𝑥𝐴 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
3130in1 41448 . . . . . . . . 9 ((𝑥𝐴 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
32 idn1 41451 . . . . . . . . . . . 12 (   (𝑥𝐴𝑥𝐴)   ▶   (𝑥𝐴𝑥𝐴)   )
33 simpl 486 . . . . . . . . . . . 12 ((𝑥𝐴𝑥𝐴) → 𝑥𝐴)
3432, 33e1a 41504 . . . . . . . . . . 11 (   (𝑥𝐴𝑥𝐴)   ▶   𝑥𝐴   )
35 orc 864 . . . . . . . . . . 11 (𝑥𝐴 → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3634, 35e1a 41504 . . . . . . . . . 10 (   (𝑥𝐴𝑥𝐴)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
3736in1 41448 . . . . . . . . 9 ((𝑥𝐴𝑥𝐴) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
3831, 37jaoi 854 . . . . . . . 8 (((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
39 olc 865 . . . . . . . . . . 11 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4013, 39e1a 41504 . . . . . . . . . 10 (   (𝑥𝐵 ∧ ¬ 𝑥𝐶)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
4140in1 41448 . . . . . . . . 9 ((𝑥𝐵 ∧ ¬ 𝑥𝐶) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
42 idn1 41451 . . . . . . . . . . . 12 (   (𝑥𝐵𝑥𝐴)   ▶   (𝑥𝐵𝑥𝐴)   )
43 simpr 488 . . . . . . . . . . . 12 ((𝑥𝐵𝑥𝐴) → 𝑥𝐴)
4442, 43e1a 41504 . . . . . . . . . . 11 (   (𝑥𝐵𝑥𝐴)   ▶   𝑥𝐴   )
4544, 35e1a 41504 . . . . . . . . . 10 (   (𝑥𝐵𝑥𝐴)   ▶   (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶))   )
4645in1 41448 . . . . . . . . 9 ((𝑥𝐵𝑥𝐴) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4741, 46jaoi 854 . . . . . . . 8 (((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4838, 47jaoi 854 . . . . . . 7 ((((𝑥𝐴 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐴𝑥𝐴)) ∨ ((𝑥𝐵 ∧ ¬ 𝑥𝐶) ∨ (𝑥𝐵𝑥𝐴))) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
4926, 48sylbir 238 . . . . . 6 (((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)) → (𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)))
5024, 49impbii 212 . . . . 5 ((𝑥𝐴 ∨ (𝑥𝐵 ∧ ¬ 𝑥𝐶)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
514, 50bitri 278 . . . 4 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
52 eldif 3893 . . . . 5 (𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ (𝑥 ∈ (𝐴𝐵) ∧ ¬ 𝑥 ∈ (𝐶𝐴)))
53 elun 4079 . . . . . 6 (𝑥 ∈ (𝐴𝐵) ↔ (𝑥𝐴𝑥𝐵))
54 eldif 3893 . . . . . . . 8 (𝑥 ∈ (𝐶𝐴) ↔ (𝑥𝐶 ∧ ¬ 𝑥𝐴))
5554notbii 323 . . . . . . 7 𝑥 ∈ (𝐶𝐴) ↔ ¬ (𝑥𝐶 ∧ ¬ 𝑥𝐴))
56 pm4.53 983 . . . . . . 7 (¬ (𝑥𝐶 ∧ ¬ 𝑥𝐴) ↔ (¬ 𝑥𝐶𝑥𝐴))
5755, 56bitri 278 . . . . . 6 𝑥 ∈ (𝐶𝐴) ↔ (¬ 𝑥𝐶𝑥𝐴))
5853, 57anbi12i 629 . . . . 5 ((𝑥 ∈ (𝐴𝐵) ∧ ¬ 𝑥 ∈ (𝐶𝐴)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
5952, 58bitri 278 . . . 4 (𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ ((𝑥𝐴𝑥𝐵) ∧ (¬ 𝑥𝐶𝑥𝐴)))
6051, 59bitr4i 281 . . 3 (𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)))
6160ax-gen 1797 . 2 𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴)))
62 dfcleq 2792 . . 3 ((𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴)) ↔ ∀𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴))))
6362biimpri 231 . 2 (∀𝑥(𝑥 ∈ (𝐴 ∪ (𝐵𝐶)) ↔ 𝑥 ∈ ((𝐴𝐵) ∖ (𝐶𝐴))) → (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴)))
6461, 63e0a 41649 1 (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∖ (𝐶𝐴))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   ↔ wb 209   ∧ wa 399   ∨ wo 844  ∀wal 1536   = wceq 1538   ∈ wcel 2111   ∖ cdif 3880   ∪ cun 3881 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2113  ax-9 2121  ax-ext 2770 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-ex 1782  df-sb 2070  df-clab 2777  df-cleq 2791  df-clel 2870  df-v 3444  df-dif 3886  df-un 3888  df-vd1 41447 This theorem is referenced by: (None)
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