Theorem nninfdcinf 7171

Description: The Weak Limited Principle of Omniscience (WLPO) implies that it is decidable whether an element of ℕ_∞ equals the point at infinity. (Contributed by Jim Kingdon, 3-Dec-2024.)

Hypotheses

Ref	Expression
nninfdcinf.w	⊢ (𝜑 → ω ∈ WOmni)
nninfdcinf.n	⊢ (𝜑 → 𝑁 ∈ ℕ∞)

Assertion

Ref	Expression
nninfdcinf	⊢ (𝜑 → DECID 𝑁 = (𝑖 ∈ ω ↦ 1o))

Distinct variable groups:   𝑖,𝑁   𝜑,𝑖

Proof of Theorem nninfdcinf

Dummy variables 𝑓 𝑥 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		fveq1 5516	. . . . . 6 ⊢ (𝑓 = 𝑁 → (𝑓‘𝑥) = (𝑁‘𝑥))
2	1	eqeq1d 2186	. . . . 5 ⊢ (𝑓 = 𝑁 → ((𝑓‘𝑥) = 1o ↔ (𝑁‘𝑥) = 1o))
3	2	ralbidv 2477	. . . 4 ⊢ (𝑓 = 𝑁 → (∀𝑥 ∈ ω (𝑓‘𝑥) = 1o ↔ ∀𝑥 ∈ ω (𝑁‘𝑥) = 1o))
4	3	dcbid 838	. . 3 ⊢ (𝑓 = 𝑁 → (DECID ∀𝑥 ∈ ω (𝑓‘𝑥) = 1o ↔ DECID ∀𝑥 ∈ ω (𝑁‘𝑥) = 1o))
5		nninfdcinf.w	. . . 4 ⊢ (𝜑 → ω ∈ WOmni)
6	5	elexd 2752	. . . . 5 ⊢ (𝜑 → ω ∈ V)
7		iswomnimap 7166	. . . . 5 ⊢ (ω ∈ V → (ω ∈ WOmni ↔ ∀𝑓 ∈ (2o ↑𝑚 ω)DECID ∀𝑥 ∈ ω (𝑓‘𝑥) = 1o))
8	6, 7	syl 14	. . . 4 ⊢ (𝜑 → (ω ∈ WOmni ↔ ∀𝑓 ∈ (2o ↑𝑚 ω)DECID ∀𝑥 ∈ ω (𝑓‘𝑥) = 1o))
9	5, 8	mpbid 147	. . 3 ⊢ (𝜑 → ∀𝑓 ∈ (2o ↑𝑚 ω)DECID ∀𝑥 ∈ ω (𝑓‘𝑥) = 1o)
10		nninfdcinf.n	. . . . 5 ⊢ (𝜑 → 𝑁 ∈ ℕ∞)
11		nninff 7123	. . . . 5 ⊢ (𝑁 ∈ ℕ∞ → 𝑁:ω⟶2o)
12	10, 11	syl 14	. . . 4 ⊢ (𝜑 → 𝑁:ω⟶2o)
13		2onn 6524	. . . . . 6 ⊢ 2o ∈ ω
14	13	elexi 2751	. . . . 5 ⊢ 2o ∈ V
15		omex 4594	. . . . 5 ⊢ ω ∈ V
16	14, 15	elmap 6679	. . . 4 ⊢ (𝑁 ∈ (2o ↑𝑚 ω) ↔ 𝑁:ω⟶2o)
17	12, 16	sylibr 134	. . 3 ⊢ (𝜑 → 𝑁 ∈ (2o ↑𝑚 ω))
18	4, 9, 17	rspcdva 2848	. 2 ⊢ (𝜑 → DECID ∀𝑥 ∈ ω (𝑁‘𝑥) = 1o)
19	12	ffnd 5368	. . . 4 ⊢ (𝜑 → 𝑁 Fn ω)
20		eqidd 2178	. . . 4 ⊢ (𝑥 = 𝑖 → 1o = 1o)
21		1onn 6523	. . . . 5 ⊢ 1o ∈ ω
22	21	a1i 9	. . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ ω) → 1o ∈ ω)
23	21	a1i 9	. . . 4 ⊢ ((𝜑 ∧ 𝑖 ∈ ω) → 1o ∈ ω)
24	19, 20, 22, 23	fnmptfvd 5622	. . 3 ⊢ (𝜑 → (𝑁 = (𝑖 ∈ ω ↦ 1o) ↔ ∀𝑥 ∈ ω (𝑁‘𝑥) = 1o))
25	24	dcbid 838	. 2 ⊢ (𝜑 → (DECID 𝑁 = (𝑖 ∈ ω ↦ 1o) ↔ DECID ∀𝑥 ∈ ω (𝑁‘𝑥) = 1o))
26	18, 25	mpbird 167	1 ⊢ (𝜑 → DECID 𝑁 = (𝑖 ∈ ω ↦ 1o))

Syntax hints:   → wi 4   ∧ wa 104   ↔ wb 105  DECID wdc 834   = wceq 1353   ∈ wcel 2148  ∀wral 2455  Vcvv 2739   ↦ cmpt 4066  ωcom 4591  ⟶wf 5214  ‘cfv 5218  (class class class)co 5877  1_oc1o 6412  2_oc2o 6413   ↑_𝑚 cmap 6650  ℕ_∞xnninf 7120  WOmnicwomni 7163

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 614  ax-in2 615  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-13 2150  ax-14 2151  ax-ext 2159  ax-sep 4123  ax-nul 4131  ax-pow 4176  ax-pr 4211  ax-un 4435  ax-setind 4538  ax-iinf 4589

This theorem depends on definitions:  df-bi 117  df-dc 835  df-3an 980  df-tru 1356  df-fal 1359  df-nf 1461  df-sb 1763  df-eu 2029  df-mo 2030  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-ne 2348  df-ral 2460  df-rex 2461  df-rab 2464  df-v 2741  df-sbc 2965  df-csb 3060  df-dif 3133  df-un 3135  df-in 3137  df-ss 3144  df-nul 3425  df-pw 3579  df-sn 3600  df-pr 3601  df-op 3603  df-uni 3812  df-int 3847  df-br 4006  df-opab 4067  df-mpt 4068  df-id 4295  df-suc 4373  df-iom 4592  df-xp 4634  df-rel 4635  df-cnv 4636  df-co 4637  df-dm 4638  df-rn 4639  df-iota 5180  df-fun 5220  df-fn 5221  df-f 5222  df-fv 5226  df-ov 5880  df-oprab 5881  df-mpo 5882  df-1o 6419  df-2o 6420  df-map 6652  df-nninf 7121  df-womni 7164

This theorem is referenced by: (None)