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Theorem xnn0lenn0nn0 9679
 Description: An extended nonnegative integer which is less than or equal to a nonnegative integer is a nonnegative integer. (Contributed by AV, 24-Nov-2021.)
Assertion
Ref Expression
xnn0lenn0nn0 ((𝑀 ∈ ℕ0*𝑁 ∈ ℕ0𝑀𝑁) → 𝑀 ∈ ℕ0)

Proof of Theorem xnn0lenn0nn0
StepHypRef Expression
1 elxnn0 9067 . . 3 (𝑀 ∈ ℕ0* ↔ (𝑀 ∈ ℕ0𝑀 = +∞))
2 2a1 25 . . . 4 (𝑀 ∈ ℕ0 → (𝑁 ∈ ℕ0 → (𝑀𝑁𝑀 ∈ ℕ0)))
3 breq1 3940 . . . . . . 7 (𝑀 = +∞ → (𝑀𝑁 ↔ +∞ ≤ 𝑁))
43adantr 274 . . . . . 6 ((𝑀 = +∞ ∧ 𝑁 ∈ ℕ0) → (𝑀𝑁 ↔ +∞ ≤ 𝑁))
5 nn0re 9011 . . . . . . . . . 10 (𝑁 ∈ ℕ0𝑁 ∈ ℝ)
65rexrd 7840 . . . . . . . . 9 (𝑁 ∈ ℕ0𝑁 ∈ ℝ*)
7 xgepnf 9630 . . . . . . . . 9 (𝑁 ∈ ℝ* → (+∞ ≤ 𝑁𝑁 = +∞))
86, 7syl 14 . . . . . . . 8 (𝑁 ∈ ℕ0 → (+∞ ≤ 𝑁𝑁 = +∞))
9 pnfnre 7832 . . . . . . . . 9 +∞ ∉ ℝ
10 eleq1 2203 . . . . . . . . . . 11 (𝑁 = +∞ → (𝑁 ∈ ℕ0 ↔ +∞ ∈ ℕ0))
11 nn0re 9011 . . . . . . . . . . . 12 (+∞ ∈ ℕ0 → +∞ ∈ ℝ)
12 elnelall 2416 . . . . . . . . . . . 12 (+∞ ∈ ℝ → (+∞ ∉ ℝ → 𝑀 ∈ ℕ0))
1311, 12syl 14 . . . . . . . . . . 11 (+∞ ∈ ℕ0 → (+∞ ∉ ℝ → 𝑀 ∈ ℕ0))
1410, 13syl6bi 162 . . . . . . . . . 10 (𝑁 = +∞ → (𝑁 ∈ ℕ0 → (+∞ ∉ ℝ → 𝑀 ∈ ℕ0)))
1514com13 80 . . . . . . . . 9 (+∞ ∉ ℝ → (𝑁 ∈ ℕ0 → (𝑁 = +∞ → 𝑀 ∈ ℕ0)))
169, 15ax-mp 5 . . . . . . . 8 (𝑁 ∈ ℕ0 → (𝑁 = +∞ → 𝑀 ∈ ℕ0))
178, 16sylbid 149 . . . . . . 7 (𝑁 ∈ ℕ0 → (+∞ ≤ 𝑁𝑀 ∈ ℕ0))
1817adantl 275 . . . . . 6 ((𝑀 = +∞ ∧ 𝑁 ∈ ℕ0) → (+∞ ≤ 𝑁𝑀 ∈ ℕ0))
194, 18sylbid 149 . . . . 5 ((𝑀 = +∞ ∧ 𝑁 ∈ ℕ0) → (𝑀𝑁𝑀 ∈ ℕ0))
2019ex 114 . . . 4 (𝑀 = +∞ → (𝑁 ∈ ℕ0 → (𝑀𝑁𝑀 ∈ ℕ0)))
212, 20jaoi 706 . . 3 ((𝑀 ∈ ℕ0𝑀 = +∞) → (𝑁 ∈ ℕ0 → (𝑀𝑁𝑀 ∈ ℕ0)))
221, 21sylbi 120 . 2 (𝑀 ∈ ℕ0* → (𝑁 ∈ ℕ0 → (𝑀𝑁𝑀 ∈ ℕ0)))
23223imp 1176 1 ((𝑀 ∈ ℕ0*𝑁 ∈ ℕ0𝑀𝑁) → 𝑀 ∈ ℕ0)
 Colors of variables: wff set class Syntax hints:   → wi 4   ∧ wa 103   ↔ wb 104   ∨ wo 698   ∧ w3a 963   = wceq 1332   ∈ wcel 1481   ∉ wnel 2404   class class class wbr 3937  ℝcr 7644  +∞cpnf 7822  ℝ*cxr 7824   ≤ cle 7826  ℕ0cn0 9002  ℕ0*cxnn0 9065 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1424  ax-7 1425  ax-gen 1426  ax-ie1 1470  ax-ie2 1471  ax-8 1483  ax-10 1484  ax-11 1485  ax-i12 1486  ax-bndl 1487  ax-4 1488  ax-13 1492  ax-14 1493  ax-17 1507  ax-i9 1511  ax-ial 1515  ax-i5r 1516  ax-ext 2122  ax-sep 4054  ax-pow 4106  ax-pr 4139  ax-un 4363  ax-setind 4460  ax-cnex 7736  ax-resscn 7737  ax-1re 7739  ax-addrcl 7742  ax-rnegex 7754  ax-pre-ltirr 7757 This theorem depends on definitions:  df-bi 116  df-3or 964  df-3an 965  df-tru 1335  df-fal 1338  df-nf 1438  df-sb 1737  df-eu 2003  df-mo 2004  df-clab 2127  df-cleq 2133  df-clel 2136  df-nfc 2271  df-ne 2310  df-nel 2405  df-ral 2422  df-rex 2423  df-rab 2426  df-v 2691  df-dif 3078  df-un 3080  df-in 3082  df-ss 3089  df-pw 3517  df-sn 3538  df-pr 3539  df-op 3541  df-uni 3745  df-int 3780  df-br 3938  df-opab 3998  df-xp 4553  df-cnv 4555  df-pnf 7827  df-mnf 7828  df-xr 7829  df-ltxr 7830  df-le 7831  df-inn 8746  df-n0 9003  df-xnn0 9066 This theorem is referenced by:  xnn0le2is012  9680
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