Theorem bndndx 8180

Description: A bounded real sequence 𝐴(𝑘) is less than or equal to at least one of its indices. (Contributed by NM, 18-Jan-2008.)

Assertion

Ref	Expression
bndndx	⊢ (∃𝑥 ∈ ℝ ∀𝑘 ∈ ℕ (𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → ∃𝑘 ∈ ℕ 𝐴 ≤ 𝑘)

Distinct variable groups:   𝑥,𝐴   𝑥,𝑘

Allowed substitution hint:   𝐴(𝑘)

Proof of Theorem bndndx

Step	Hyp	Ref	Expression
1		arch 8178	. . . 4 ⊢ (𝑥 ∈ ℝ → ∃𝑘 ∈ ℕ 𝑥 < 𝑘)
2		nnre 7921	. . . . . 6 ⊢ (𝑘 ∈ ℕ → 𝑘 ∈ ℝ)
3		lelttr 7106	. . . . . . . . . . 11 ⊢ ((𝐴 ∈ ℝ ∧ 𝑥 ∈ ℝ ∧ 𝑘 ∈ ℝ) → ((𝐴 ≤ 𝑥 ∧ 𝑥 < 𝑘) → 𝐴 < 𝑘))
4		ltle 7105	. . . . . . . . . . . 12 ⊢ ((𝐴 ∈ ℝ ∧ 𝑘 ∈ ℝ) → (𝐴 < 𝑘 → 𝐴 ≤ 𝑘))
5	4	3adant2 923	. . . . . . . . . . 11 ⊢ ((𝐴 ∈ ℝ ∧ 𝑥 ∈ ℝ ∧ 𝑘 ∈ ℝ) → (𝐴 < 𝑘 → 𝐴 ≤ 𝑘))
6	3, 5	syld 40	. . . . . . . . . 10 ⊢ ((𝐴 ∈ ℝ ∧ 𝑥 ∈ ℝ ∧ 𝑘 ∈ ℝ) → ((𝐴 ≤ 𝑥 ∧ 𝑥 < 𝑘) → 𝐴 ≤ 𝑘))
7	6	exp5o 1123	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → (𝑥 ∈ ℝ → (𝑘 ∈ ℝ → (𝐴 ≤ 𝑥 → (𝑥 < 𝑘 → 𝐴 ≤ 𝑘)))))
8	7	com3l 75	. . . . . . . 8 ⊢ (𝑥 ∈ ℝ → (𝑘 ∈ ℝ → (𝐴 ∈ ℝ → (𝐴 ≤ 𝑥 → (𝑥 < 𝑘 → 𝐴 ≤ 𝑘)))))
9	8	imp4b 332	. . . . . . 7 ⊢ ((𝑥 ∈ ℝ ∧ 𝑘 ∈ ℝ) → ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → (𝑥 < 𝑘 → 𝐴 ≤ 𝑘)))
10	9	com23 72	. . . . . 6 ⊢ ((𝑥 ∈ ℝ ∧ 𝑘 ∈ ℝ) → (𝑥 < 𝑘 → ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → 𝐴 ≤ 𝑘)))
11	2, 10	sylan2 270	. . . . 5 ⊢ ((𝑥 ∈ ℝ ∧ 𝑘 ∈ ℕ) → (𝑥 < 𝑘 → ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → 𝐴 ≤ 𝑘)))
12	11	reximdva 2421	. . . 4 ⊢ (𝑥 ∈ ℝ → (∃𝑘 ∈ ℕ 𝑥 < 𝑘 → ∃𝑘 ∈ ℕ ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → 𝐴 ≤ 𝑘)))
13	1, 12	mpd 13	. . 3 ⊢ (𝑥 ∈ ℝ → ∃𝑘 ∈ ℕ ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → 𝐴 ≤ 𝑘))
14		r19.35-1 2460	. . 3 ⊢ (∃𝑘 ∈ ℕ ((𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → 𝐴 ≤ 𝑘) → (∀𝑘 ∈ ℕ (𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → ∃𝑘 ∈ ℕ 𝐴 ≤ 𝑘))
15	13, 14	syl 14	. 2 ⊢ (𝑥 ∈ ℝ → (∀𝑘 ∈ ℕ (𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → ∃𝑘 ∈ ℕ 𝐴 ≤ 𝑘))
16	15	rexlimiv 2427	1 ⊢ (∃𝑥 ∈ ℝ ∀𝑘 ∈ ℕ (𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → ∃𝑘 ∈ ℕ 𝐴 ≤ 𝑘)

Syntax hints:   → wi 4   ∧ wa 97   ∧ w3a 885   ∈ wcel 1393  ∀wral 2306  ∃wrex 2307   class class class wbr 3764  ℝcr 6888   < clt 7060   ≤ cle 7061  ℕcn 7914

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-13 1404  ax-14 1405  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022  ax-sep 3875  ax-pow 3927  ax-pr 3944  ax-un 4170  ax-setind 4262  ax-cnex 6975  ax-resscn 6976  ax-1re 6978  ax-addrcl 6981  ax-pre-ltirr 6996  ax-pre-ltwlin 6997  ax-pre-lttrn 6998  ax-arch 7003

This theorem depends on definitions:  df-bi 110  df-3an 887  df-tru 1246  df-fal 1249  df-nf 1350  df-sb 1646  df-eu 1903  df-mo 1904  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ne 2206  df-nel 2207  df-ral 2311  df-rex 2312  df-rab 2315  df-v 2559  df-dif 2920  df-un 2922  df-in 2924  df-ss 2931  df-pw 3361  df-sn 3381  df-pr 3382  df-op 3384  df-uni 3581  df-int 3616  df-br 3765  df-opab 3819  df-xp 4351  df-cnv 4353  df-pnf 7062  df-mnf 7063  df-xr 7064  df-ltxr 7065  df-le 7066  df-inn 7915

This theorem is referenced by: (None)