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Mirrors > Home > ILE Home > Th. List > snsspr1 | GIF version |
Description: A singleton is a subset of an unordered pair containing its member. (Contributed by NM, 27-Aug-2004.) |
Ref | Expression |
---|---|
snsspr1 | ⊢ {A} ⊆ {A, B} |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssun1 3100 | . 2 ⊢ {A} ⊆ ({A} ∪ {B}) | |
2 | df-pr 3374 | . 2 ⊢ {A, B} = ({A} ∪ {B}) | |
3 | 1, 2 | sseqtr4i 2972 | 1 ⊢ {A} ⊆ {A, B} |
Colors of variables: wff set class |
Syntax hints: ∪ cun 2909 ⊆ wss 2911 {csn 3367 {cpr 3368 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-io 629 ax-5 1333 ax-7 1334 ax-gen 1335 ax-ie1 1379 ax-ie2 1380 ax-8 1392 ax-10 1393 ax-11 1394 ax-i12 1395 ax-bndl 1396 ax-4 1397 ax-17 1416 ax-i9 1420 ax-ial 1424 ax-i5r 1425 ax-ext 2019 |
This theorem depends on definitions: df-bi 110 df-tru 1245 df-nf 1347 df-sb 1643 df-clab 2024 df-cleq 2030 df-clel 2033 df-nfc 2164 df-v 2553 df-un 2916 df-in 2918 df-ss 2925 df-pr 3374 |
This theorem is referenced by: snsstp1 3505 ssprr 3518 uniop 3983 op1stb 4175 op1stbg 4176 ltrelxr 6877 |
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