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Mirrors > Home > MPE Home > Th. List > modom | Structured version Visualization version GIF version |
Description: Two ways to express "at most one". (Contributed by Stefan O'Rear, 28-Oct-2014.) |
Ref | Expression |
---|---|
modom | ⊢ (∃*𝑥𝜑 ↔ {𝑥 ∣ 𝜑} ≼ 1o) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | moeu 2664 | . 2 ⊢ (∃*𝑥𝜑 ↔ (∃𝑥𝜑 → ∃!𝑥𝜑)) | |
2 | imor 849 | . 2 ⊢ ((∃𝑥𝜑 → ∃!𝑥𝜑) ↔ (¬ ∃𝑥𝜑 ∨ ∃!𝑥𝜑)) | |
3 | abn0 4336 | . . . . . 6 ⊢ ({𝑥 ∣ 𝜑} ≠ ∅ ↔ ∃𝑥𝜑) | |
4 | 3 | necon1bbii 3065 | . . . . 5 ⊢ (¬ ∃𝑥𝜑 ↔ {𝑥 ∣ 𝜑} = ∅) |
5 | sdom1 8712 | . . . . 5 ⊢ ({𝑥 ∣ 𝜑} ≺ 1o ↔ {𝑥 ∣ 𝜑} = ∅) | |
6 | 4, 5 | bitr4i 280 | . . . 4 ⊢ (¬ ∃𝑥𝜑 ↔ {𝑥 ∣ 𝜑} ≺ 1o) |
7 | euen1 8573 | . . . 4 ⊢ (∃!𝑥𝜑 ↔ {𝑥 ∣ 𝜑} ≈ 1o) | |
8 | 6, 7 | orbi12i 911 | . . 3 ⊢ ((¬ ∃𝑥𝜑 ∨ ∃!𝑥𝜑) ↔ ({𝑥 ∣ 𝜑} ≺ 1o ∨ {𝑥 ∣ 𝜑} ≈ 1o)) |
9 | brdom2 8533 | . . 3 ⊢ ({𝑥 ∣ 𝜑} ≼ 1o ↔ ({𝑥 ∣ 𝜑} ≺ 1o ∨ {𝑥 ∣ 𝜑} ≈ 1o)) | |
10 | 8, 9 | bitr4i 280 | . 2 ⊢ ((¬ ∃𝑥𝜑 ∨ ∃!𝑥𝜑) ↔ {𝑥 ∣ 𝜑} ≼ 1o) |
11 | 1, 2, 10 | 3bitri 299 | 1 ⊢ (∃*𝑥𝜑 ↔ {𝑥 ∣ 𝜑} ≼ 1o) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 208 ∨ wo 843 = wceq 1533 ∃wex 1776 ∃*wmo 2616 ∃!weu 2649 {cab 2799 ∅c0 4291 class class class wbr 5059 1oc1o 8089 ≈ cen 8500 ≼ cdom 8501 ≺ csdm 8502 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1907 ax-6 1966 ax-7 2011 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2156 ax-12 2172 ax-ext 2793 ax-sep 5196 ax-nul 5203 ax-pow 5259 ax-pr 5322 ax-un 7455 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1536 df-ex 1777 df-nf 1781 df-sb 2066 df-mo 2618 df-eu 2650 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-ral 3143 df-rex 3144 df-reu 3145 df-rab 3147 df-v 3497 df-sbc 3773 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-pss 3954 df-nul 4292 df-if 4468 df-pw 4541 df-sn 4562 df-pr 4564 df-tp 4566 df-op 4568 df-uni 4833 df-br 5060 df-opab 5122 df-tr 5166 df-id 5455 df-eprel 5460 df-po 5469 df-so 5470 df-fr 5509 df-we 5511 df-xp 5556 df-rel 5557 df-cnv 5558 df-co 5559 df-dm 5560 df-rn 5561 df-res 5562 df-ima 5563 df-ord 6189 df-on 6190 df-lim 6191 df-suc 6192 df-iota 6309 df-fun 6352 df-fn 6353 df-f 6354 df-f1 6355 df-fo 6356 df-f1o 6357 df-fv 6358 df-om 7575 df-1o 8096 df-er 8283 df-en 8504 df-dom 8505 df-sdom 8506 |
This theorem is referenced by: modom2 8714 |
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