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Mirrors > Home > MPE Home > Th. List > difsnid | Structured version Visualization version GIF version |
Description: If we remove a single element from a class then put it back in, we end up with the original class. (Contributed by NM, 2-Oct-2006.) |
Ref | Expression |
---|---|
difsnid | ⊢ (𝐵 ∈ 𝐴 → ((𝐴 ∖ {𝐵}) ∪ {𝐵}) = 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | uncom 4129 | . 2 ⊢ ((𝐴 ∖ {𝐵}) ∪ {𝐵}) = ({𝐵} ∪ (𝐴 ∖ {𝐵})) | |
2 | snssi 4735 | . . 3 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ⊆ 𝐴) | |
3 | undif 4430 | . . 3 ⊢ ({𝐵} ⊆ 𝐴 ↔ ({𝐵} ∪ (𝐴 ∖ {𝐵})) = 𝐴) | |
4 | 2, 3 | sylib 220 | . 2 ⊢ (𝐵 ∈ 𝐴 → ({𝐵} ∪ (𝐴 ∖ {𝐵})) = 𝐴) |
5 | 1, 4 | syl5eq 2868 | 1 ⊢ (𝐵 ∈ 𝐴 → ((𝐴 ∖ {𝐵}) ∪ {𝐵}) = 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1533 ∈ wcel 2110 ∖ cdif 3933 ∪ cun 3934 ⊆ wss 3936 {csn 4561 |
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 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3an 1085 df-tru 1536 df-ex 1777 df-nf 1781 df-sb 2066 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-rab 3147 df-v 3497 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-nul 4292 df-sn 4562 |
This theorem is referenced by: fnsnsplit 6941 fsnunf2 6943 difsnexi 7477 difsnen 8593 enfixsn 8620 phplem2 8691 pssnn 8730 dif1en 8745 frfi 8757 xpfi 8783 dif1card 9430 hashgt23el 13779 hashfun 13792 fprodfvdvdsd 15677 prmdvdsprmo 16372 mreexexlem4d 16912 symgextf1 18543 symgextfo 18544 symgfixf1 18559 gsumdifsnd 19075 gsummgp0 19352 islindf4 20976 scmatf1 21134 gsummatr01 21262 tdeglem4 24648 finsumvtxdg2sstep 27325 dfconngr1 27961 satfv1lem 32604 bj-raldifsn 34386 lindsadd 34879 lindsenlbs 34881 poimirlem25 34911 poimirlem27 34913 hdmap14lem4a 39001 hdmap14lem13 39010 supxrmnf2 41699 infxrpnf2 41731 fsumnncl 41844 hoidmv1lelem2 42867 gsumdifsndf 44081 mgpsumunsn 44402 |
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