![]() |
Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > MPE Home > Th. List > snsssn | Structured version Visualization version GIF version |
Description: If a singleton is a subset of another, their members are equal. (Contributed by NM, 28-May-2006.) |
Ref | Expression |
---|---|
sneqr.1 | ⊢ 𝐴 ∈ V |
Ref | Expression |
---|---|
snsssn | ⊢ ({𝐴} ⊆ {𝐵} → 𝐴 = 𝐵) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sssn 4831 | . 2 ⊢ ({𝐴} ⊆ {𝐵} ↔ ({𝐴} = ∅ ∨ {𝐴} = {𝐵})) | |
2 | sneqr.1 | . . . . . 6 ⊢ 𝐴 ∈ V | |
3 | 2 | snnz 4781 | . . . . 5 ⊢ {𝐴} ≠ ∅ |
4 | 3 | neii 2940 | . . . 4 ⊢ ¬ {𝐴} = ∅ |
5 | 4 | pm2.21i 119 | . . 3 ⊢ ({𝐴} = ∅ → 𝐴 = 𝐵) |
6 | 2 | sneqr 4845 | . . 3 ⊢ ({𝐴} = {𝐵} → 𝐴 = 𝐵) |
7 | 5, 6 | jaoi 857 | . 2 ⊢ (({𝐴} = ∅ ∨ {𝐴} = {𝐵}) → 𝐴 = 𝐵) |
8 | 1, 7 | sylbi 217 | 1 ⊢ ({𝐴} ⊆ {𝐵} → 𝐴 = 𝐵) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∨ wo 847 = wceq 1537 ∈ wcel 2106 Vcvv 3478 ⊆ wss 3963 ∅c0 4339 {csn 4631 |
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 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-ext 2706 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-tru 1540 df-fal 1550 df-ex 1777 df-sb 2063 df-clab 2713 df-cleq 2727 df-clel 2814 df-ne 2939 df-v 3480 df-dif 3966 df-ss 3980 df-nul 4340 df-sn 4632 |
This theorem is referenced by: k0004lem3 44139 |
Copyright terms: Public domain | W3C validator |