Theorem pssdifcom2 3636

Description: Two ways to express non-covering pairs of subsets. (Contributed by Stefan O'Rear, 31-Oct-2014.)

Assertion

Ref	Expression
pssdifcom2	⊢ ((A ⊆ C ∧ B ⊆ C) → (B ⊊ (C ∖ A) ↔ A ⊊ (C ∖ B)))

Proof of Theorem pssdifcom2

Step	Hyp	Ref	Expression
1		ssconb 3399	. . . 4 ⊢ ((B ⊆ C ∧ A ⊆ C) → (B ⊆ (C ∖ A) ↔ A ⊆ (C ∖ B)))
2	1	ancoms 439	. . 3 ⊢ ((A ⊆ C ∧ B ⊆ C) → (B ⊆ (C ∖ A) ↔ A ⊆ (C ∖ B)))
3		difcom 3634	. . . . 5 ⊢ ((C ∖ A) ⊆ B ↔ (C ∖ B) ⊆ A)
4	3	a1i 10	. . . 4 ⊢ ((A ⊆ C ∧ B ⊆ C) → ((C ∖ A) ⊆ B ↔ (C ∖ B) ⊆ A))
5	4	notbid 285	. . 3 ⊢ ((A ⊆ C ∧ B ⊆ C) → (¬ (C ∖ A) ⊆ B ↔ ¬ (C ∖ B) ⊆ A))
6	2, 5	anbi12d 691	. 2 ⊢ ((A ⊆ C ∧ B ⊆ C) → ((B ⊆ (C ∖ A) ∧ ¬ (C ∖ A) ⊆ B) ↔ (A ⊆ (C ∖ B) ∧ ¬ (C ∖ B) ⊆ A)))
7		dfpss3 3355	. 2 ⊢ (B ⊊ (C ∖ A) ↔ (B ⊆ (C ∖ A) ∧ ¬ (C ∖ A) ⊆ B))
8		dfpss3 3355	. 2 ⊢ (A ⊊ (C ∖ B) ↔ (A ⊆ (C ∖ B) ∧ ¬ (C ∖ B) ⊆ A))
9	6, 7, 8	3bitr4g 279	1 ⊢ ((A ⊆ C ∧ B ⊆ C) → (B ⊊ (C ∖ A) ↔ A ⊊ (C ∖ B)))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 176   ∧ wa 358   ∖ cdif 3206   ⊆ wss 3257   ⊊ wpss 3258

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-ne 2518  df-v 2861  df-nin 3211  df-compl 3212  df-in 3213  df-un 3214  df-dif 3215  df-ss 3259  df-pss 3261

This theorem is referenced by: (None)