Theorem ab0w 4274

Description: The class of sets verifying a property is the empty class if and only if that property is a contradiction. Version of ab0 4275 using implicit substitution, which requires fewer axioms. (Contributed by Gino Giotto, 3-Oct-2024.)

Hypothesis

Ref	Expression
ab0w.1	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
ab0w	⊢ ({𝑥 ∣ 𝜑} = ∅ ↔ ∀𝑦 ¬ 𝜓)

Distinct variable groups:   𝑥,𝑦   𝜑,𝑦   𝜓,𝑥

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)

Proof of Theorem ab0w

Step	Hyp	Ref	Expression
1		dfnul4 4225	. . 3 ⊢ ∅ = {𝑥 ∣ ⊥}
2	1	eqeq2i 2749	. 2 ⊢ ({𝑥 ∣ 𝜑} = ∅ ↔ {𝑥 ∣ 𝜑} = {𝑥 ∣ ⊥})
3		dfcleq 2729	. . . 4 ⊢ ({𝑥 ∣ 𝜑} = {𝑥 ∣ ⊥} ↔ ∀𝑦(𝑦 ∈ {𝑥 ∣ 𝜑} ↔ 𝑦 ∈ {𝑥 ∣ ⊥}))
4		df-clab 2715	. . . . . . . 8 ⊢ (𝑦 ∈ {𝑥 ∣ 𝜑} ↔ [𝑦 / 𝑥]𝜑)
5		ab0w.1	. . . . . . . . 9 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
6	5	sbievw 2101	. . . . . . . 8 ⊢ ([𝑦 / 𝑥]𝜑 ↔ 𝜓)
7	4, 6	bitri 278	. . . . . . 7 ⊢ (𝑦 ∈ {𝑥 ∣ 𝜑} ↔ 𝜓)
8	7	bibi1i 342	. . . . . 6 ⊢ ((𝑦 ∈ {𝑥 ∣ 𝜑} ↔ 𝑦 ∈ {𝑥 ∣ ⊥}) ↔ (𝜓 ↔ 𝑦 ∈ {𝑥 ∣ ⊥}))
9		bicom 225	. . . . . 6 ⊢ ((𝜓 ↔ 𝑦 ∈ {𝑥 ∣ ⊥}) ↔ (𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓))
10	8, 9	bitri 278	. . . . 5 ⊢ ((𝑦 ∈ {𝑥 ∣ 𝜑} ↔ 𝑦 ∈ {𝑥 ∣ ⊥}) ↔ (𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓))
11	10	albii 1827	. . . 4 ⊢ (∀𝑦(𝑦 ∈ {𝑥 ∣ 𝜑} ↔ 𝑦 ∈ {𝑥 ∣ ⊥}) ↔ ∀𝑦(𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓))
12	3, 11	bitri 278	. . 3 ⊢ ({𝑥 ∣ 𝜑} = {𝑥 ∣ ⊥} ↔ ∀𝑦(𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓))
13		df-clab 2715	. . . . . . 7 ⊢ (𝑦 ∈ {𝑥 ∣ ⊥} ↔ [𝑦 / 𝑥]⊥)
14		sbv 2096	. . . . . . 7 ⊢ ([𝑦 / 𝑥]⊥ ↔ ⊥)
15	13, 14	bitri 278	. . . . . 6 ⊢ (𝑦 ∈ {𝑥 ∣ ⊥} ↔ ⊥)
16	15	bibi1i 342	. . . . 5 ⊢ ((𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓) ↔ (⊥ ↔ 𝜓))
17	16	albii 1827	. . . 4 ⊢ (∀𝑦(𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓) ↔ ∀𝑦(⊥ ↔ 𝜓))
18		falim 1560	. . . . . . 7 ⊢ (⊥ → (𝜓 → ¬ 𝜓))
19		idd 24	. . . . . . 7 ⊢ (¬ ⊥ → (¬ 𝜓 → ¬ 𝜓))
20	18, 19	bija 385	. . . . . 6 ⊢ ((⊥ ↔ 𝜓) → ¬ 𝜓)
21		falim 1560	. . . . . . 7 ⊢ (⊥ → 𝜓)
22		id 22	. . . . . . 7 ⊢ (𝜓 → 𝜓)
23	21, 22	pm5.21ni 382	. . . . . 6 ⊢ (¬ 𝜓 → (⊥ ↔ 𝜓))
24	20, 23	impbii 212	. . . . 5 ⊢ ((⊥ ↔ 𝜓) ↔ ¬ 𝜓)
25	24	albii 1827	. . . 4 ⊢ (∀𝑦(⊥ ↔ 𝜓) ↔ ∀𝑦 ¬ 𝜓)
26	17, 25	bitri 278	. . 3 ⊢ (∀𝑦(𝑦 ∈ {𝑥 ∣ ⊥} ↔ 𝜓) ↔ ∀𝑦 ¬ 𝜓)
27	12, 26	bitri 278	. 2 ⊢ ({𝑥 ∣ 𝜑} = {𝑥 ∣ ⊥} ↔ ∀𝑦 ¬ 𝜓)
28	2, 27	bitri 278	1 ⊢ ({𝑥 ∣ 𝜑} = ∅ ↔ ∀𝑦 ¬ 𝜓)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 209  ∀wal 1541   = wceq 1543  ⊥wfal 1555  [wsb 2072   ∈ wcel 2112  {cab 2714  ∅c0 4223

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1803  ax-4 1817  ax-5 1918  ax-6 1976  ax-7 2018  ax-9 2122  ax-ext 2708

This theorem depends on definitions:  df-bi 210  df-an 400  df-tru 1546  df-fal 1556  df-ex 1788  df-sb 2073  df-clab 2715  df-cleq 2728  df-dif 3856  df-nul 4224

This theorem is referenced by:  rabeq0w  4284  0mpo0  7272  fsetdmprc0  8514