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Mirrors > Home > MPE Home > Th. List > cnvcnvss | Structured version Visualization version GIF version |
Description: The double converse of a class is a subclass. Exercise 2 of [TakeutiZaring] p. 25. (Contributed by NM, 23-Jul-2004.) |
Ref | Expression |
---|---|
cnvcnvss | ⊢ ◡◡𝐴 ⊆ 𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cnvcnv 5586 | . 2 ⊢ ◡◡𝐴 = (𝐴 ∩ (V × V)) | |
2 | inss1 3833 | . 2 ⊢ (𝐴 ∩ (V × V)) ⊆ 𝐴 | |
3 | 1, 2 | eqsstri 3635 | 1 ⊢ ◡◡𝐴 ⊆ 𝐴 |
Colors of variables: wff setvar class |
Syntax hints: Vcvv 3200 ∩ cin 3573 ⊆ wss 3574 × cxp 5112 ◡ccnv 5113 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1722 ax-4 1737 ax-5 1839 ax-6 1888 ax-7 1935 ax-9 1999 ax-10 2019 ax-11 2034 ax-12 2047 ax-13 2246 ax-ext 2602 ax-sep 4781 ax-nul 4789 ax-pr 4906 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 df-3an 1039 df-tru 1486 df-ex 1705 df-nf 1710 df-sb 1881 df-eu 2474 df-mo 2475 df-clab 2609 df-cleq 2615 df-clel 2618 df-nfc 2753 df-ral 2917 df-rab 2921 df-v 3202 df-dif 3577 df-un 3579 df-in 3581 df-ss 3588 df-nul 3916 df-if 4087 df-sn 4178 df-pr 4180 df-op 4184 df-br 4654 df-opab 4713 df-xp 5120 df-rel 5121 df-cnv 5122 |
This theorem is referenced by: funcnvcnv 5956 foimacnv 6154 cnvct 8033 cnvfi 8248 structcnvcnv 15871 strlemor1OLD 15969 mvdco 17865 fcoinver 29418 fcnvgreu 29472 cnvssb 37892 relnonrel 37893 clcnvlem 37930 cnvtrrel 37962 relexpaddss 38010 |
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