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Mirrors > Home > MPE Home > Th. List > prdom2 | Structured version Visualization version GIF version |
Description: An unordered pair has at most two elements. (Contributed by FL, 22-Feb-2011.) |
Ref | Expression |
---|---|
prdom2 | ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → {𝐴, 𝐵} ≼ 2𝑜) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfsn2 4329 | . . . . . 6 ⊢ {𝐴} = {𝐴, 𝐴} | |
2 | ensn1g 8174 | . . . . . . 7 ⊢ (𝐴 ∈ 𝐶 → {𝐴} ≈ 1𝑜) | |
3 | endom 8136 | . . . . . . . 8 ⊢ ({𝐴} ≈ 1𝑜 → {𝐴} ≼ 1𝑜) | |
4 | 1sdom2 8315 | . . . . . . . 8 ⊢ 1𝑜 ≺ 2𝑜 | |
5 | domsdomtr 8251 | . . . . . . . . 9 ⊢ (({𝐴} ≼ 1𝑜 ∧ 1𝑜 ≺ 2𝑜) → {𝐴} ≺ 2𝑜) | |
6 | sdomdom 8137 | . . . . . . . . 9 ⊢ ({𝐴} ≺ 2𝑜 → {𝐴} ≼ 2𝑜) | |
7 | 5, 6 | syl 17 | . . . . . . . 8 ⊢ (({𝐴} ≼ 1𝑜 ∧ 1𝑜 ≺ 2𝑜) → {𝐴} ≼ 2𝑜) |
8 | 3, 4, 7 | sylancl 566 | . . . . . . 7 ⊢ ({𝐴} ≈ 1𝑜 → {𝐴} ≼ 2𝑜) |
9 | 2, 8 | syl 17 | . . . . . 6 ⊢ (𝐴 ∈ 𝐶 → {𝐴} ≼ 2𝑜) |
10 | 1, 9 | syl5eqbrr 4822 | . . . . 5 ⊢ (𝐴 ∈ 𝐶 → {𝐴, 𝐴} ≼ 2𝑜) |
11 | preq2 4405 | . . . . . 6 ⊢ (𝐵 = 𝐴 → {𝐴, 𝐵} = {𝐴, 𝐴}) | |
12 | 11 | breq1d 4796 | . . . . 5 ⊢ (𝐵 = 𝐴 → ({𝐴, 𝐵} ≼ 2𝑜 ↔ {𝐴, 𝐴} ≼ 2𝑜)) |
13 | 10, 12 | syl5ibr 236 | . . . 4 ⊢ (𝐵 = 𝐴 → (𝐴 ∈ 𝐶 → {𝐴, 𝐵} ≼ 2𝑜)) |
14 | 13 | eqcoms 2779 | . . 3 ⊢ (𝐴 = 𝐵 → (𝐴 ∈ 𝐶 → {𝐴, 𝐵} ≼ 2𝑜)) |
15 | 14 | adantrd 475 | . 2 ⊢ (𝐴 = 𝐵 → ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → {𝐴, 𝐵} ≼ 2𝑜)) |
16 | pr2ne 9028 | . . . 4 ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → ({𝐴, 𝐵} ≈ 2𝑜 ↔ 𝐴 ≠ 𝐵)) | |
17 | 16 | biimprd 238 | . . 3 ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → (𝐴 ≠ 𝐵 → {𝐴, 𝐵} ≈ 2𝑜)) |
18 | endom 8136 | . . 3 ⊢ ({𝐴, 𝐵} ≈ 2𝑜 → {𝐴, 𝐵} ≼ 2𝑜) | |
19 | 17, 18 | syl6com 37 | . 2 ⊢ (𝐴 ≠ 𝐵 → ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → {𝐴, 𝐵} ≼ 2𝑜)) |
20 | 15, 19 | pm2.61ine 3026 | 1 ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷) → {𝐴, 𝐵} ≼ 2𝑜) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 382 = wceq 1631 ∈ wcel 2145 ≠ wne 2943 {csn 4316 {cpr 4318 class class class wbr 4786 1𝑜c1o 7706 2𝑜c2o 7707 ≈ cen 8106 ≼ cdom 8107 ≺ csdm 8108 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1870 ax-4 1885 ax-5 1991 ax-6 2057 ax-7 2093 ax-8 2147 ax-9 2154 ax-10 2174 ax-11 2190 ax-12 2203 ax-13 2408 ax-ext 2751 ax-sep 4915 ax-nul 4923 ax-pow 4974 ax-pr 5034 ax-un 7096 |
This theorem depends on definitions: df-bi 197 df-an 383 df-or 827 df-3or 1072 df-3an 1073 df-tru 1634 df-ex 1853 df-nf 1858 df-sb 2050 df-eu 2622 df-mo 2623 df-clab 2758 df-cleq 2764 df-clel 2767 df-nfc 2902 df-ne 2944 df-ral 3066 df-rex 3067 df-reu 3068 df-rab 3070 df-v 3353 df-sbc 3588 df-dif 3726 df-un 3728 df-in 3730 df-ss 3737 df-pss 3739 df-nul 4064 df-if 4226 df-pw 4299 df-sn 4317 df-pr 4319 df-tp 4321 df-op 4323 df-uni 4575 df-br 4787 df-opab 4847 df-tr 4887 df-id 5157 df-eprel 5162 df-po 5170 df-so 5171 df-fr 5208 df-we 5210 df-xp 5255 df-rel 5256 df-cnv 5257 df-co 5258 df-dm 5259 df-rn 5260 df-res 5261 df-ima 5262 df-ord 5869 df-on 5870 df-lim 5871 df-suc 5872 df-iota 5994 df-fun 6033 df-fn 6034 df-f 6035 df-f1 6036 df-fo 6037 df-f1o 6038 df-fv 6039 df-om 7213 df-1o 7713 df-2o 7714 df-er 7896 df-en 8110 df-dom 8111 df-sdom 8112 |
This theorem is referenced by: (None) |
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