Theorem elpwdifsn 4757

Description: A subset of a set is an element of the power set of the difference of the set with a singleton if the subset does not contain the singleton element. (Contributed by AV, 10-Jan-2020.)

Assertion

Ref	Expression
elpwdifsn	⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → 𝑆 ∈ 𝒫 (𝑉 ∖ {𝐴}))

Proof of Theorem elpwdifsn

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		simp2 1155	. . . . . 6 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → 𝑆 ⊆ 𝑉)
2	1	sselda 3937	. . . . 5 ⊢ (((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) ∧ 𝑥 ∈ 𝑆) → 𝑥 ∈ 𝑉)
3		df-nel 3065	. . . . . . . . 9 ⊢ (𝐴 ∉ 𝑆 ↔ ¬ 𝐴 ∈ 𝑆)
4	3	biimpi 219	. . . . . . . 8 ⊢ (𝐴 ∉ 𝑆 → ¬ 𝐴 ∈ 𝑆)
5	4	3ad2ant3 1153	. . . . . . 7 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → ¬ 𝐴 ∈ 𝑆)
6	5	anim1ci 627	. . . . . 6 ⊢ (((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) ∧ 𝑥 ∈ 𝑆) → (𝑥 ∈ 𝑆 ∧ ¬ 𝐴 ∈ 𝑆))
7		nelne2 3056	. . . . . 6 ⊢ ((𝑥 ∈ 𝑆 ∧ ¬ 𝐴 ∈ 𝑆) → 𝑥 ≠ 𝐴)
8	6, 7	syl 18	. . . . 5 ⊢ (((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) ∧ 𝑥 ∈ 𝑆) → 𝑥 ≠ 𝐴)
9	2, 8	eldifsnd 4755	. . . 4 ⊢ (((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) ∧ 𝑥 ∈ 𝑆) → 𝑥 ∈ (𝑉 ∖ {𝐴}))
10	9	ex 417	. . 3 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → (𝑥 ∈ 𝑆 → 𝑥 ∈ (𝑉 ∖ {𝐴})))
11	10	ssrdv 3943	. 2 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → 𝑆 ⊆ (𝑉 ∖ {𝐴}))
12		elpwg 4565	. . 3 ⊢ (𝑆 ∈ 𝑊 → (𝑆 ∈ 𝒫 (𝑉 ∖ {𝐴}) ↔ 𝑆 ⊆ (𝑉 ∖ {𝐴})))
13	12	3ad2ant1 1151	. 2 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → (𝑆 ∈ 𝒫 (𝑉 ∖ {𝐴}) ↔ 𝑆 ⊆ (𝑉 ∖ {𝐴})))
14	11, 13	mpbird 260	1 ⊢ ((𝑆 ∈ 𝑊 ∧ 𝑆 ⊆ 𝑉 ∧ 𝐴 ∉ 𝑆) → 𝑆 ∈ 𝒫 (𝑉 ∖ {𝐴}))

This proof depends on syntax axioms:  ¬ wn 3   → wi 4   ↔ wb 209   ∧ wa 400   ∧ w3a 1103   ∈ wcel 2143   ≠ wne 2958   ∉ wnel 3064   ∖ cdif 3902   ⊆ wss 3905  𝒫 cpw 4562  {csn 4589

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1825  ax-4 1839  ax-5 1940  ax-6 1997  ax-7 2038  ax-8 2145  ax-9 2153  ax-ext 2735

This proof depends on definitions:  df-bi 210  df-an 401  df-3an 1105  df-tru 1573  df-ex 1810  df-sb 2097  df-clab 2742  df-cleq 2755  df-clel 2838  df-ne 2959  df-nel 3065  df-v 3457  df-dif 3908  df-ss 3922  df-pw 4564  df-sn 4590

This theorem is used by:  uhgrspan1  29662  upgrreslem  29663  umgrreslem  29664  umgrres1lem  29669  upgrres1  29672