Theorem gpg3nbgrvtx0ALT 48058

Description: In a generalized Petersen graph 𝐺, every outside vertex has exactly three (different) neighbors. (Contributed by AV, 30-Aug-2025.)

The proof of gpg3nbgrvtx0 48057 can be shortened using modmknepk 47353, but then theorem 2ltceilhalf 47319 is required which is based on an "example" ex-ceil 30383. If these theorems were moved to main, the "example" should also be moved up to become a full-fledged theorem. (Proof shortened by AV, 4-Sep-2025.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypotheses

Ref	Expression
gpgnbgr.j	⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))
gpgnbgr.g	⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)
gpgnbgr.v	⊢ 𝑉 = (Vtx‘𝐺)
gpgnbgr.u	⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)

Assertion

Ref	Expression
gpg3nbgrvtx0ALT	⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (♯‘𝑈) = 3)

Proof of Theorem gpg3nbgrvtx0ALT

Step	Hyp	Ref	Expression
1		gpgnbgr.j	. . . 4 ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))
2		gpgnbgr.g	. . . 4 ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)
3		gpgnbgr.v	. . . 4 ⊢ 𝑉 = (Vtx‘𝐺)
4		gpgnbgr.u	. . . 4 ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)
5	1, 2, 3, 4	gpgnbgrvtx0 48055	. . 3 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → 𝑈 = {⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩, ⟨1, (2nd ‘𝑋)⟩, ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩})
6	5	fveq2d 6864	. 2 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (♯‘𝑈) = (♯‘{⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩, ⟨1, (2nd ‘𝑋)⟩, ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩}))
7		0ne1 12258	. . . . . . 7 ⊢ 0 ≠ 1
8	7	a1i 11	. . . . . 6 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → 0 ≠ 1)
9	8	orcd 873	. . . . 5 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (0 ≠ 1 ∨ (((2nd ‘𝑋) + 1) mod 𝑁) ≠ (2nd ‘𝑋)))
10		c0ex 11174	. . . . . 6 ⊢ 0 ∈ V
11		ovex 7422	. . . . . 6 ⊢ (((2nd ‘𝑋) + 1) mod 𝑁) ∈ V
12	10, 11	opthne 5444	. . . . 5 ⊢ (⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ≠ ⟨1, (2nd ‘𝑋)⟩ ↔ (0 ≠ 1 ∨ (((2nd ‘𝑋) + 1) mod 𝑁) ≠ (2nd ‘𝑋)))
13	9, 12	sylibr 234	. . . 4 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ≠ ⟨1, (2nd ‘𝑋)⟩)
14		ax-1ne0 11143	. . . . . . 7 ⊢ 1 ≠ 0
15	14	a1i 11	. . . . . 6 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → 1 ≠ 0)
16	15	orcd 873	. . . . 5 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (1 ≠ 0 ∨ (2nd ‘𝑋) ≠ (((2nd ‘𝑋) − 1) mod 𝑁)))
17		1ex 11176	. . . . . 6 ⊢ 1 ∈ V
18		fvex 6873	. . . . . 6 ⊢ (2nd ‘𝑋) ∈ V
19	17, 18	opthne 5444	. . . . 5 ⊢ (⟨1, (2nd ‘𝑋)⟩ ≠ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ↔ (1 ≠ 0 ∨ (2nd ‘𝑋) ≠ (((2nd ‘𝑋) − 1) mod 𝑁)))
20	16, 19	sylibr 234	. . . 4 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → ⟨1, (2nd ‘𝑋)⟩ ≠ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩)
21		simpll 766	. . . . . . 7 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → 𝑁 ∈ (ℤ≥‘3))
22		eqid 2730	. . . . . . . . 9 ⊢ (0..^𝑁) = (0..^𝑁)
23	22, 1, 2, 3	gpgvtxel2 48029	. . . . . . . 8 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ 𝑋 ∈ 𝑉) → (2nd ‘𝑋) ∈ (0..^𝑁))
24	23	adantrr 717	. . . . . . 7 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (2nd ‘𝑋) ∈ (0..^𝑁))
25		2z 12571	. . . . . . . . . . 11 ⊢ 2 ∈ ℤ
26	25	a1i 11	. . . . . . . . . 10 ⊢ (𝑁 ∈ (ℤ≥‘3) → 2 ∈ ℤ)
27		eluzelre 12810	. . . . . . . . . . . 12 ⊢ (𝑁 ∈ (ℤ≥‘3) → 𝑁 ∈ ℝ)
28	27	rehalfcld 12435	. . . . . . . . . . 11 ⊢ (𝑁 ∈ (ℤ≥‘3) → (𝑁 / 2) ∈ ℝ)
29	28	ceilcld 13811	. . . . . . . . . 10 ⊢ (𝑁 ∈ (ℤ≥‘3) → (⌈‘(𝑁 / 2)) ∈ ℤ)
30		2ltceilhalf 47319	. . . . . . . . . 10 ⊢ (𝑁 ∈ (ℤ≥‘3) → 2 ≤ (⌈‘(𝑁 / 2)))
31		eluz2 12805	. . . . . . . . . 10 ⊢ ((⌈‘(𝑁 / 2)) ∈ (ℤ≥‘2) ↔ (2 ∈ ℤ ∧ (⌈‘(𝑁 / 2)) ∈ ℤ ∧ 2 ≤ (⌈‘(𝑁 / 2))))
32	26, 29, 30, 31	syl3anbrc 1344	. . . . . . . . 9 ⊢ (𝑁 ∈ (ℤ≥‘3) → (⌈‘(𝑁 / 2)) ∈ (ℤ≥‘2))
33		fzo1lb 13680	. . . . . . . . 9 ⊢ (1 ∈ (1..^(⌈‘(𝑁 / 2))) ↔ (⌈‘(𝑁 / 2)) ∈ (ℤ≥‘2))
34	32, 33	sylibr 234	. . . . . . . 8 ⊢ (𝑁 ∈ (ℤ≥‘3) → 1 ∈ (1..^(⌈‘(𝑁 / 2))))
35	34	ad2antrr 726	. . . . . . 7 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → 1 ∈ (1..^(⌈‘(𝑁 / 2))))
36		eqid 2730	. . . . . . . 8 ⊢ (1..^(⌈‘(𝑁 / 2))) = (1..^(⌈‘(𝑁 / 2)))
37	36, 22	modmknepk 47353	. . . . . . 7 ⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ (2nd ‘𝑋) ∈ (0..^𝑁) ∧ 1 ∈ (1..^(⌈‘(𝑁 / 2)))) → (((2nd ‘𝑋) − 1) mod 𝑁) ≠ (((2nd ‘𝑋) + 1) mod 𝑁))
38	21, 24, 35, 37	syl3anc 1373	. . . . . 6 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (((2nd ‘𝑋) − 1) mod 𝑁) ≠ (((2nd ‘𝑋) + 1) mod 𝑁))
39	38	olcd 874	. . . . 5 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (0 ≠ 0 ∨ (((2nd ‘𝑋) − 1) mod 𝑁) ≠ (((2nd ‘𝑋) + 1) mod 𝑁)))
40		ovex 7422	. . . . . 6 ⊢ (((2nd ‘𝑋) − 1) mod 𝑁) ∈ V
41	10, 40	opthne 5444	. . . . 5 ⊢ (⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ≠ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ↔ (0 ≠ 0 ∨ (((2nd ‘𝑋) − 1) mod 𝑁) ≠ (((2nd ‘𝑋) + 1) mod 𝑁)))
42	39, 41	sylibr 234	. . . 4 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ≠ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩)
43	13, 20, 42	3jca 1128	. . 3 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ≠ ⟨1, (2nd ‘𝑋)⟩ ∧ ⟨1, (2nd ‘𝑋)⟩ ≠ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∧ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ≠ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩))
44		opex 5426	. . . 4 ⊢ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ∈ V
45		opex 5426	. . . 4 ⊢ ⟨1, (2nd ‘𝑋)⟩ ∈ V
46		opex 5426	. . . 4 ⊢ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∈ V
47		hashtpg 14456	. . . 4 ⊢ ((⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ∈ V ∧ ⟨1, (2nd ‘𝑋)⟩ ∈ V ∧ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∈ V) → ((⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ≠ ⟨1, (2nd ‘𝑋)⟩ ∧ ⟨1, (2nd ‘𝑋)⟩ ≠ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∧ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ≠ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩) ↔ (♯‘{⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩, ⟨1, (2nd ‘𝑋)⟩, ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩}) = 3))
48	44, 45, 46, 47	mp3an 1463	. . 3 ⊢ ((⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ≠ ⟨1, (2nd ‘𝑋)⟩ ∧ ⟨1, (2nd ‘𝑋)⟩ ≠ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∧ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ≠ ⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩) ↔ (♯‘{⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩, ⟨1, (2nd ‘𝑋)⟩, ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩}) = 3)
49	43, 48	sylib 218	. 2 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (♯‘{⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩, ⟨1, (2nd ‘𝑋)⟩, ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩}) = 3)
50	6, 49	eqtrd 2765	1 ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ (𝑋 ∈ 𝑉 ∧ (1st ‘𝑋) = 0)) → (♯‘𝑈) = 3)

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   ∨ wo 847   ∧ w3a 1086   = wceq 1540   ∈ wcel 2109   ≠ wne 2926  Vcvv 3450  {ctp 4595  ⟨cop 4597   class class class wbr 5109  ‘cfv 6513  (class class class)co 7389  1^st c1st 7968  2^nd c2nd 7969  0cc0 11074  1c1 11075   + caddc 11077   ≤ cle 11215   − cmin 11411   / cdiv 11841  2c2 12242  3c3 12243  ℤcz 12535  ℤ_≥cuz 12799  ..^cfzo 13621  ⌈cceil 13759   mod cmo 13837  ♯chash 14301  Vtxcvtx 28929   NeighbVtx cnbgr 29265   gPetersenGr cgpg 48021

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-10 2142  ax-11 2158  ax-12 2178  ax-ext 2702  ax-rep 5236  ax-sep 5253  ax-nul 5263  ax-pow 5322  ax-pr 5389  ax-un 7713  ax-cnex 11130  ax-resscn 11131  ax-1cn 11132  ax-icn 11133  ax-addcl 11134  ax-addrcl 11135  ax-mulcl 11136  ax-mulrcl 11137  ax-mulcom 11138  ax-addass 11139  ax-mulass 11140  ax-distr 11141  ax-i2m1 11142  ax-1ne0 11143  ax-1rid 11144  ax-rnegex 11145  ax-rrecex 11146  ax-cnre 11147  ax-pre-lttri 11148  ax-pre-lttrn 11149  ax-pre-ltadd 11150  ax-pre-mulgt0 11151  ax-pre-sup 11152

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-nf 1784  df-sb 2066  df-mo 2534  df-eu 2563  df-clab 2709  df-cleq 2722  df-clel 2804  df-nfc 2879  df-ne 2927  df-nel 3031  df-ral 3046  df-rex 3055  df-rmo 3356  df-reu 3357  df-rab 3409  df-v 3452  df-sbc 3756  df-csb 3865  df-dif 3919  df-un 3921  df-in 3923  df-ss 3933  df-pss 3936  df-nul 4299  df-if 4491  df-pw 4567  df-sn 4592  df-pr 4594  df-tp 4596  df-op 4598  df-uni 4874  df-int 4913  df-iun 4959  df-br 5110  df-opab 5172  df-mpt 5191  df-tr 5217  df-id 5535  df-eprel 5540  df-po 5548  df-so 5549  df-fr 5593  df-we 5595  df-xp 5646  df-rel 5647  df-cnv 5648  df-co 5649  df-dm 5650  df-rn 5651  df-res 5652  df-ima 5653  df-pred 6276  df-ord 6337  df-on 6338  df-lim 6339  df-suc 6340  df-iota 6466  df-fun 6515  df-fn 6516  df-f 6517  df-f1 6518  df-fo 6519  df-f1o 6520  df-fv 6521  df-riota 7346  df-ov 7392  df-oprab 7393  df-mpo 7394  df-om 7845  df-1st 7970  df-2nd 7971  df-frecs 8262  df-wrecs 8293  df-recs 8342  df-rdg 8380  df-1o 8436  df-2o 8437  df-oadd 8440  df-er 8673  df-en 8921  df-dom 8922  df-sdom 8923  df-fin 8924  df-sup 9399  df-inf 9400  df-dju 9860  df-card 9898  df-pnf 11216  df-mnf 11217  df-xr 11218  df-ltxr 11219  df-le 11220  df-sub 11413  df-neg 11414  df-div 11842  df-nn 12188  df-2 12250  df-3 12251  df-4 12252  df-5 12253  df-6 12254  df-7 12255  df-8 12256  df-9 12257  df-n0 12449  df-xnn0 12522  df-z 12536  df-dec 12656  df-uz 12800  df-rp 12958  df-fz 13475  df-fzo 13622  df-fl 13760  df-ceil 13761  df-mod 13838  df-hash 14302  df-dvds 16229  df-struct 17123  df-slot 17158  df-ndx 17170  df-base 17186  df-edgf 28922  df-vtx 28931  df-iedg 28932  df-edg 28981  df-upgr 29015  df-umgr 29016  df-usgr 29084  df-nbgr 29266  df-gpg 48022

This theorem is referenced by: (None)