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Mirrors > Home > MPE Home > Th. List > snnen2o | Structured version Visualization version GIF version |
Description: A singleton {𝐴} is never equinumerous with the ordinal number 2. This holds for proper singletons (𝐴 ∈ V) as well as for singletons being the empty set (𝐴 ∉ V). (Contributed by AV, 6-Aug-2019.) |
Ref | Expression |
---|---|
snnen2o | ⊢ ¬ {𝐴} ≈ 2o |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 1onn 8267 | . . . 4 ⊢ 1o ∈ ω | |
2 | php5 8707 | . . . 4 ⊢ (1o ∈ ω → ¬ 1o ≈ suc 1o) | |
3 | 1, 2 | ax-mp 5 | . . 3 ⊢ ¬ 1o ≈ suc 1o |
4 | ensn1g 8576 | . . 3 ⊢ (𝐴 ∈ V → {𝐴} ≈ 1o) | |
5 | df-2o 8105 | . . . . . 6 ⊢ 2o = suc 1o | |
6 | 5 | eqcomi 2832 | . . . . 5 ⊢ suc 1o = 2o |
7 | 6 | breq2i 5076 | . . . 4 ⊢ (1o ≈ suc 1o ↔ 1o ≈ 2o) |
8 | ensymb 8559 | . . . . . 6 ⊢ ({𝐴} ≈ 1o ↔ 1o ≈ {𝐴}) | |
9 | entr 8563 | . . . . . . 7 ⊢ ((1o ≈ {𝐴} ∧ {𝐴} ≈ 2o) → 1o ≈ 2o) | |
10 | 9 | ex 415 | . . . . . 6 ⊢ (1o ≈ {𝐴} → ({𝐴} ≈ 2o → 1o ≈ 2o)) |
11 | 8, 10 | sylbi 219 | . . . . 5 ⊢ ({𝐴} ≈ 1o → ({𝐴} ≈ 2o → 1o ≈ 2o)) |
12 | 11 | con3rr3 158 | . . . 4 ⊢ (¬ 1o ≈ 2o → ({𝐴} ≈ 1o → ¬ {𝐴} ≈ 2o)) |
13 | 7, 12 | sylnbi 332 | . . 3 ⊢ (¬ 1o ≈ suc 1o → ({𝐴} ≈ 1o → ¬ {𝐴} ≈ 2o)) |
14 | 3, 4, 13 | mpsyl 68 | . 2 ⊢ (𝐴 ∈ V → ¬ {𝐴} ≈ 2o) |
15 | 2on0 8115 | . . . 4 ⊢ 2o ≠ ∅ | |
16 | ensymb 8559 | . . . . 5 ⊢ (∅ ≈ 2o ↔ 2o ≈ ∅) | |
17 | en0 8574 | . . . . 5 ⊢ (2o ≈ ∅ ↔ 2o = ∅) | |
18 | 16, 17 | bitri 277 | . . . 4 ⊢ (∅ ≈ 2o ↔ 2o = ∅) |
19 | 15, 18 | nemtbir 3114 | . . 3 ⊢ ¬ ∅ ≈ 2o |
20 | snprc 4655 | . . . . 5 ⊢ (¬ 𝐴 ∈ V ↔ {𝐴} = ∅) | |
21 | 20 | biimpi 218 | . . . 4 ⊢ (¬ 𝐴 ∈ V → {𝐴} = ∅) |
22 | 21 | breq1d 5078 | . . 3 ⊢ (¬ 𝐴 ∈ V → ({𝐴} ≈ 2o ↔ ∅ ≈ 2o)) |
23 | 19, 22 | mtbiri 329 | . 2 ⊢ (¬ 𝐴 ∈ V → ¬ {𝐴} ≈ 2o) |
24 | 14, 23 | pm2.61i 184 | 1 ⊢ ¬ {𝐴} ≈ 2o |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 = wceq 1537 ∈ wcel 2114 Vcvv 3496 ∅c0 4293 {csn 4569 class class class wbr 5068 suc csuc 6195 ωcom 7582 1oc1o 8097 2oc2o 8098 ≈ cen 8508 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2795 ax-sep 5205 ax-nul 5212 ax-pow 5268 ax-pr 5332 ax-un 7463 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2802 df-cleq 2816 df-clel 2895 df-nfc 2965 df-ne 3019 df-ral 3145 df-rex 3146 df-rab 3149 df-v 3498 df-sbc 3775 df-dif 3941 df-un 3943 df-in 3945 df-ss 3954 df-pss 3956 df-nul 4294 df-if 4470 df-pw 4543 df-sn 4570 df-pr 4572 df-tp 4574 df-op 4576 df-uni 4841 df-br 5069 df-opab 5131 df-tr 5175 df-id 5462 df-eprel 5467 df-po 5476 df-so 5477 df-fr 5516 df-we 5518 df-xp 5563 df-rel 5564 df-cnv 5565 df-co 5566 df-dm 5567 df-rn 5568 df-res 5569 df-ima 5570 df-ord 6196 df-on 6197 df-lim 6198 df-suc 6199 df-iota 6316 df-fun 6359 df-fn 6360 df-f 6361 df-f1 6362 df-fo 6363 df-f1o 6364 df-fv 6365 df-om 7583 df-1o 8104 df-2o 8105 df-er 8291 df-en 8512 df-dom 8513 df-sdom 8514 |
This theorem is referenced by: pmtrsn 18649 trivnsimpgd 19221 |
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