Theorem rabrsndc 3438

Description: A class abstraction over a decidable proposition restricted to a singleton is either the empty set or the singleton itself. (Contributed by Jim Kingdon, 8-Aug-2018.)

Hypotheses

Ref	Expression
rabrsndc.1	⊢ 𝐴 ∈ V
rabrsndc.2	⊢ DECID 𝜑

Assertion

Ref	Expression
rabrsndc	⊢ (𝑀 = {𝑥 ∈ {𝐴} ∣ 𝜑} → (𝑀 = ∅ ∨ 𝑀 = {𝐴}))

Distinct variable group:   𝑥,𝐴

Allowed substitution hints:   𝜑(𝑥)   𝑀(𝑥)

Proof of Theorem rabrsndc

Step	Hyp	Ref	Expression
1		rabrsndc.1	. . . . . 6 ⊢ 𝐴 ∈ V
2		rabrsndc.2	. . . . . . . 8 ⊢ DECID 𝜑
3		pm2.1dc 745	. . . . . . . 8 ⊢ (DECID 𝜑 → (¬ 𝜑 ∨ 𝜑))
4	2, 3	ax-mp 7	. . . . . . 7 ⊢ (¬ 𝜑 ∨ 𝜑)
5	4	sbcth 2777	. . . . . 6 ⊢ (𝐴 ∈ V → [𝐴 / 𝑥](¬ 𝜑 ∨ 𝜑))
6	1, 5	ax-mp 7	. . . . 5 ⊢ [𝐴 / 𝑥](¬ 𝜑 ∨ 𝜑)
7		sbcor 2807	. . . . 5 ⊢ ([𝐴 / 𝑥](¬ 𝜑 ∨ 𝜑) ↔ ([𝐴 / 𝑥] ¬ 𝜑 ∨ [𝐴 / 𝑥]𝜑))
8	6, 7	mpbi 133	. . . 4 ⊢ ([𝐴 / 𝑥] ¬ 𝜑 ∨ [𝐴 / 𝑥]𝜑)
9		ralsns 3408	. . . . . 6 ⊢ (𝐴 ∈ V → (∀𝑥 ∈ {𝐴} ¬ 𝜑 ↔ [𝐴 / 𝑥] ¬ 𝜑))
10	1, 9	ax-mp 7	. . . . 5 ⊢ (∀𝑥 ∈ {𝐴} ¬ 𝜑 ↔ [𝐴 / 𝑥] ¬ 𝜑)
11		ralsns 3408	. . . . . 6 ⊢ (𝐴 ∈ V → (∀𝑥 ∈ {𝐴}𝜑 ↔ [𝐴 / 𝑥]𝜑))
12	1, 11	ax-mp 7	. . . . 5 ⊢ (∀𝑥 ∈ {𝐴}𝜑 ↔ [𝐴 / 𝑥]𝜑)
13	10, 12	orbi12i 681	. . . 4 ⊢ ((∀𝑥 ∈ {𝐴} ¬ 𝜑 ∨ ∀𝑥 ∈ {𝐴}𝜑) ↔ ([𝐴 / 𝑥] ¬ 𝜑 ∨ [𝐴 / 𝑥]𝜑))
14	8, 13	mpbir 134	. . 3 ⊢ (∀𝑥 ∈ {𝐴} ¬ 𝜑 ∨ ∀𝑥 ∈ {𝐴}𝜑)
15		rabeq0 3247	. . . 4 ⊢ ({𝑥 ∈ {𝐴} ∣ 𝜑} = ∅ ↔ ∀𝑥 ∈ {𝐴} ¬ 𝜑)
16		eqcom 2042	. . . . 5 ⊢ ({𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴} ↔ {𝐴} = {𝑥 ∈ {𝐴} ∣ 𝜑})
17		rabid2 2486	. . . . 5 ⊢ ({𝐴} = {𝑥 ∈ {𝐴} ∣ 𝜑} ↔ ∀𝑥 ∈ {𝐴}𝜑)
18	16, 17	bitri 173	. . . 4 ⊢ ({𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴} ↔ ∀𝑥 ∈ {𝐴}𝜑)
19	15, 18	orbi12i 681	. . 3 ⊢ (({𝑥 ∈ {𝐴} ∣ 𝜑} = ∅ ∨ {𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴}) ↔ (∀𝑥 ∈ {𝐴} ¬ 𝜑 ∨ ∀𝑥 ∈ {𝐴}𝜑))
20	14, 19	mpbir 134	. 2 ⊢ ({𝑥 ∈ {𝐴} ∣ 𝜑} = ∅ ∨ {𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴})
21		eqeq1 2046	. . 3 ⊢ (𝑀 = {𝑥 ∈ {𝐴} ∣ 𝜑} → (𝑀 = ∅ ↔ {𝑥 ∈ {𝐴} ∣ 𝜑} = ∅))
22		eqeq1 2046	. . 3 ⊢ (𝑀 = {𝑥 ∈ {𝐴} ∣ 𝜑} → (𝑀 = {𝐴} ↔ {𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴}))
23	21, 22	orbi12d 707	. 2 ⊢ (𝑀 = {𝑥 ∈ {𝐴} ∣ 𝜑} → ((𝑀 = ∅ ∨ 𝑀 = {𝐴}) ↔ ({𝑥 ∈ {𝐴} ∣ 𝜑} = ∅ ∨ {𝑥 ∈ {𝐴} ∣ 𝜑} = {𝐴})))
24	20, 23	mpbiri 157	1 ⊢ (𝑀 = {𝑥 ∈ {𝐴} ∣ 𝜑} → (𝑀 = ∅ ∨ 𝑀 = {𝐴}))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 98   ∨ wo 629  DECID wdc 742   = wceq 1243   ∈ wcel 1393  ∀wral 2306  {crab 2310  Vcvv 2557  [wsbc 2764  ∅c0 3224  {csn 3375

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022

This theorem depends on definitions:  df-bi 110  df-dc 743  df-tru 1246  df-fal 1249  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ral 2311  df-rab 2315  df-v 2559  df-sbc 2765  df-dif 2920  df-nul 3225  df-sn 3381

This theorem is referenced by: (None)