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| Mirrors > Home > MPE Home > Th. List > sssn | Structured version Visualization version GIF version | ||
| Description: The subsets of a singleton. (Contributed by NM, 24-Apr-2004.) |
| Ref | Expression |
|---|---|
| sssn | ⊢ (𝐴 ⊆ {𝐵} ↔ (𝐴 = ∅ ∨ 𝐴 = {𝐵})) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | neq0 4352 | . . . . . . 7 ⊢ (¬ 𝐴 = ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) | |
| 2 | ssel 3977 | . . . . . . . . . . 11 ⊢ (𝐴 ⊆ {𝐵} → (𝑥 ∈ 𝐴 → 𝑥 ∈ {𝐵})) | |
| 3 | elsni 4643 | . . . . . . . . . . 11 ⊢ (𝑥 ∈ {𝐵} → 𝑥 = 𝐵) | |
| 4 | 2, 3 | syl6 35 | . . . . . . . . . 10 ⊢ (𝐴 ⊆ {𝐵} → (𝑥 ∈ 𝐴 → 𝑥 = 𝐵)) |
| 5 | eleq1 2829 | . . . . . . . . . 10 ⊢ (𝑥 = 𝐵 → (𝑥 ∈ 𝐴 ↔ 𝐵 ∈ 𝐴)) | |
| 6 | 4, 5 | syl6 35 | . . . . . . . . 9 ⊢ (𝐴 ⊆ {𝐵} → (𝑥 ∈ 𝐴 → (𝑥 ∈ 𝐴 ↔ 𝐵 ∈ 𝐴))) |
| 7 | 6 | ibd 269 | . . . . . . . 8 ⊢ (𝐴 ⊆ {𝐵} → (𝑥 ∈ 𝐴 → 𝐵 ∈ 𝐴)) |
| 8 | 7 | exlimdv 1933 | . . . . . . 7 ⊢ (𝐴 ⊆ {𝐵} → (∃𝑥 𝑥 ∈ 𝐴 → 𝐵 ∈ 𝐴)) |
| 9 | 1, 8 | biimtrid 242 | . . . . . 6 ⊢ (𝐴 ⊆ {𝐵} → (¬ 𝐴 = ∅ → 𝐵 ∈ 𝐴)) |
| 10 | snssi 4808 | . . . . . 6 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ⊆ 𝐴) | |
| 11 | 9, 10 | syl6 35 | . . . . 5 ⊢ (𝐴 ⊆ {𝐵} → (¬ 𝐴 = ∅ → {𝐵} ⊆ 𝐴)) |
| 12 | 11 | anc2li 555 | . . . 4 ⊢ (𝐴 ⊆ {𝐵} → (¬ 𝐴 = ∅ → (𝐴 ⊆ {𝐵} ∧ {𝐵} ⊆ 𝐴))) |
| 13 | eqss 3999 | . . . 4 ⊢ (𝐴 = {𝐵} ↔ (𝐴 ⊆ {𝐵} ∧ {𝐵} ⊆ 𝐴)) | |
| 14 | 12, 13 | imbitrrdi 252 | . . 3 ⊢ (𝐴 ⊆ {𝐵} → (¬ 𝐴 = ∅ → 𝐴 = {𝐵})) |
| 15 | 14 | orrd 864 | . 2 ⊢ (𝐴 ⊆ {𝐵} → (𝐴 = ∅ ∨ 𝐴 = {𝐵})) |
| 16 | 0ss 4400 | . . . 4 ⊢ ∅ ⊆ {𝐵} | |
| 17 | sseq1 4009 | . . . 4 ⊢ (𝐴 = ∅ → (𝐴 ⊆ {𝐵} ↔ ∅ ⊆ {𝐵})) | |
| 18 | 16, 17 | mpbiri 258 | . . 3 ⊢ (𝐴 = ∅ → 𝐴 ⊆ {𝐵}) |
| 19 | eqimss 4042 | . . 3 ⊢ (𝐴 = {𝐵} → 𝐴 ⊆ {𝐵}) | |
| 20 | 18, 19 | jaoi 858 | . 2 ⊢ ((𝐴 = ∅ ∨ 𝐴 = {𝐵}) → 𝐴 ⊆ {𝐵}) |
| 21 | 15, 20 | impbii 209 | 1 ⊢ (𝐴 ⊆ {𝐵} ↔ (𝐴 = ∅ ∨ 𝐴 = {𝐵})) |
| Colors of variables: wff setvar class |
| Syntax hints: ¬ wn 3 ↔ wb 206 ∧ wa 395 ∨ wo 848 = wceq 1540 ∃wex 1779 ∈ wcel 2108 ⊆ wss 3951 ∅c0 4333 {csn 4626 |
| 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 2007 ax-8 2110 ax-9 2118 ax-ext 2708 |
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 849 df-tru 1543 df-fal 1553 df-ex 1780 df-sb 2065 df-clab 2715 df-cleq 2729 df-clel 2816 df-v 3482 df-dif 3954 df-ss 3968 df-nul 4334 df-sn 4627 |
| This theorem is referenced by: eqsn 4829 snsssn 4841 pwsn 4900 frsn 5773 foconst 6835 fin1a2lem12 10451 fpwwe2lem12 10682 gsumval2 18699 0top 22990 minveclem4a 25464 uvtx01vtx 29414 snsssng 32533 pmtrcnelor 33111 0ringsubrg 33255 lvecdim0 33657 locfinref 33840 ordcmp 36448 bj-snmoore 37114 nlpineqsn 37409 uneqsn 44038 mosssn 48734 mosssn2 48736 mofsssn 48755 |
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