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Mirrors > Home > MPE Home > Th. List > lfgrnloop | Structured version Visualization version GIF version |
Description: A loop-free graph has no loops. (Contributed by AV, 23-Feb-2021.) |
Ref | Expression |
---|---|
lfuhgrnloopv.i | ⊢ 𝐼 = (iEdg‘𝐺) |
lfuhgrnloopv.a | ⊢ 𝐴 = dom 𝐼 |
lfuhgrnloopv.e | ⊢ 𝐸 = {𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (♯‘𝑥)} |
Ref | Expression |
---|---|
lfgrnloop | ⊢ (𝐼:𝐴⟶𝐸 → {𝑥 ∈ 𝐴 ∣ (𝐼‘𝑥) = {𝑈}} = ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nfcv 2897 | . . . 4 ⊢ Ⅎ𝑥𝐼 | |
2 | nfcv 2897 | . . . 4 ⊢ Ⅎ𝑥𝐴 | |
3 | lfuhgrnloopv.e | . . . . 5 ⊢ 𝐸 = {𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (♯‘𝑥)} | |
4 | nfrab1 3445 | . . . . 5 ⊢ Ⅎ𝑥{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (♯‘𝑥)} | |
5 | 3, 4 | nfcxfr 2895 | . . . 4 ⊢ Ⅎ𝑥𝐸 |
6 | 1, 2, 5 | nff 6707 | . . 3 ⊢ Ⅎ𝑥 𝐼:𝐴⟶𝐸 |
7 | hashsn01 14381 | . . . . . . 7 ⊢ ((♯‘{𝑈}) = 0 ∨ (♯‘{𝑈}) = 1) | |
8 | 2pos 12319 | . . . . . . . . . 10 ⊢ 0 < 2 | |
9 | 0re 11220 | . . . . . . . . . . 11 ⊢ 0 ∈ ℝ | |
10 | 2re 12290 | . . . . . . . . . . 11 ⊢ 2 ∈ ℝ | |
11 | 9, 10 | ltnlei 11339 | . . . . . . . . . 10 ⊢ (0 < 2 ↔ ¬ 2 ≤ 0) |
12 | 8, 11 | mpbi 229 | . . . . . . . . 9 ⊢ ¬ 2 ≤ 0 |
13 | breq2 5145 | . . . . . . . . 9 ⊢ ((♯‘{𝑈}) = 0 → (2 ≤ (♯‘{𝑈}) ↔ 2 ≤ 0)) | |
14 | 12, 13 | mtbiri 327 | . . . . . . . 8 ⊢ ((♯‘{𝑈}) = 0 → ¬ 2 ≤ (♯‘{𝑈})) |
15 | 1lt2 12387 | . . . . . . . . . 10 ⊢ 1 < 2 | |
16 | 1re 11218 | . . . . . . . . . . 11 ⊢ 1 ∈ ℝ | |
17 | 16, 10 | ltnlei 11339 | . . . . . . . . . 10 ⊢ (1 < 2 ↔ ¬ 2 ≤ 1) |
18 | 15, 17 | mpbi 229 | . . . . . . . . 9 ⊢ ¬ 2 ≤ 1 |
19 | breq2 5145 | . . . . . . . . 9 ⊢ ((♯‘{𝑈}) = 1 → (2 ≤ (♯‘{𝑈}) ↔ 2 ≤ 1)) | |
20 | 18, 19 | mtbiri 327 | . . . . . . . 8 ⊢ ((♯‘{𝑈}) = 1 → ¬ 2 ≤ (♯‘{𝑈})) |
21 | 14, 20 | jaoi 854 | . . . . . . 7 ⊢ (((♯‘{𝑈}) = 0 ∨ (♯‘{𝑈}) = 1) → ¬ 2 ≤ (♯‘{𝑈})) |
22 | 7, 21 | ax-mp 5 | . . . . . 6 ⊢ ¬ 2 ≤ (♯‘{𝑈}) |
23 | fveq2 6885 | . . . . . . 7 ⊢ ((𝐼‘𝑥) = {𝑈} → (♯‘(𝐼‘𝑥)) = (♯‘{𝑈})) | |
24 | 23 | breq2d 5153 | . . . . . 6 ⊢ ((𝐼‘𝑥) = {𝑈} → (2 ≤ (♯‘(𝐼‘𝑥)) ↔ 2 ≤ (♯‘{𝑈}))) |
25 | 22, 24 | mtbiri 327 | . . . . 5 ⊢ ((𝐼‘𝑥) = {𝑈} → ¬ 2 ≤ (♯‘(𝐼‘𝑥))) |
26 | lfuhgrnloopv.i | . . . . . 6 ⊢ 𝐼 = (iEdg‘𝐺) | |
27 | lfuhgrnloopv.a | . . . . . 6 ⊢ 𝐴 = dom 𝐼 | |
28 | 26, 27, 3 | lfgredgge2 28892 | . . . . 5 ⊢ ((𝐼:𝐴⟶𝐸 ∧ 𝑥 ∈ 𝐴) → 2 ≤ (♯‘(𝐼‘𝑥))) |
29 | 25, 28 | nsyl3 138 | . . . 4 ⊢ ((𝐼:𝐴⟶𝐸 ∧ 𝑥 ∈ 𝐴) → ¬ (𝐼‘𝑥) = {𝑈}) |
30 | 29 | ex 412 | . . 3 ⊢ (𝐼:𝐴⟶𝐸 → (𝑥 ∈ 𝐴 → ¬ (𝐼‘𝑥) = {𝑈})) |
31 | 6, 30 | ralrimi 3248 | . 2 ⊢ (𝐼:𝐴⟶𝐸 → ∀𝑥 ∈ 𝐴 ¬ (𝐼‘𝑥) = {𝑈}) |
32 | rabeq0 4379 | . 2 ⊢ ({𝑥 ∈ 𝐴 ∣ (𝐼‘𝑥) = {𝑈}} = ∅ ↔ ∀𝑥 ∈ 𝐴 ¬ (𝐼‘𝑥) = {𝑈}) | |
33 | 31, 32 | sylibr 233 | 1 ⊢ (𝐼:𝐴⟶𝐸 → {𝑥 ∈ 𝐴 ∣ (𝐼‘𝑥) = {𝑈}} = ∅) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 395 ∨ wo 844 = wceq 1533 ∈ wcel 2098 ∀wral 3055 {crab 3426 ∅c0 4317 𝒫 cpw 4597 {csn 4623 class class class wbr 5141 dom cdm 5669 ⟶wf 6533 ‘cfv 6537 0cc0 11112 1c1 11113 < clt 11252 ≤ cle 11253 2c2 12271 ♯chash 14295 iEdgciedg 28765 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2163 ax-ext 2697 ax-sep 5292 ax-nul 5299 ax-pow 5356 ax-pr 5420 ax-un 7722 ax-cnex 11168 ax-resscn 11169 ax-1cn 11170 ax-icn 11171 ax-addcl 11172 ax-addrcl 11173 ax-mulcl 11174 ax-mulrcl 11175 ax-mulcom 11176 ax-addass 11177 ax-mulass 11178 ax-distr 11179 ax-i2m1 11180 ax-1ne0 11181 ax-1rid 11182 ax-rnegex 11183 ax-rrecex 11184 ax-cnre 11185 ax-pre-lttri 11186 ax-pre-lttrn 11187 ax-pre-ltadd 11188 ax-pre-mulgt0 11189 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2528 df-eu 2557 df-clab 2704 df-cleq 2718 df-clel 2804 df-nfc 2879 df-ne 2935 df-nel 3041 df-ral 3056 df-rex 3065 df-reu 3371 df-rab 3427 df-v 3470 df-sbc 3773 df-csb 3889 df-dif 3946 df-un 3948 df-in 3950 df-ss 3960 df-pss 3962 df-nul 4318 df-if 4524 df-pw 4599 df-sn 4624 df-pr 4626 df-op 4630 df-uni 4903 df-int 4944 df-iun 4992 df-br 5142 df-opab 5204 df-mpt 5225 df-tr 5259 df-id 5567 df-eprel 5573 df-po 5581 df-so 5582 df-fr 5624 df-we 5626 df-xp 5675 df-rel 5676 df-cnv 5677 df-co 5678 df-dm 5679 df-rn 5680 df-res 5681 df-ima 5682 df-pred 6294 df-ord 6361 df-on 6362 df-lim 6363 df-suc 6364 df-iota 6489 df-fun 6539 df-fn 6540 df-f 6541 df-f1 6542 df-fo 6543 df-f1o 6544 df-fv 6545 df-riota 7361 df-ov 7408 df-oprab 7409 df-mpo 7410 df-om 7853 df-1st 7974 df-2nd 7975 df-frecs 8267 df-wrecs 8298 df-recs 8372 df-rdg 8411 df-1o 8467 df-er 8705 df-en 8942 df-dom 8943 df-sdom 8944 df-fin 8945 df-card 9936 df-pnf 11254 df-mnf 11255 df-xr 11256 df-ltxr 11257 df-le 11258 df-sub 11450 df-neg 11451 df-nn 12217 df-2 12279 df-n0 12477 df-z 12563 df-uz 12827 df-fz 13491 df-hash 14296 |
This theorem is referenced by: vtxdlfgrval 29251 |
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