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Mirrors > Home > ILE Home > Th. List > fun2cnv | Unicode version |
Description: The double converse of a class is a function iff the class is single-valued. Each side is equivalent to Definition 6.4(2) of [TakeutiZaring] p. 23, who use the notation "Un(A)" for single-valued. Note that is not necessarily a function. (Contributed by NM, 13-Aug-2004.) |
Ref | Expression |
---|---|
fun2cnv |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | funcnv2 4979 | . 2 | |
2 | vex 2604 | . . . . 5 | |
3 | vex 2604 | . . . . 5 | |
4 | 2, 3 | brcnv 4536 | . . . 4 |
5 | 4 | mobii 1978 | . . 3 |
6 | 5 | albii 1399 | . 2 |
7 | 1, 6 | bitri 182 | 1 |
Colors of variables: wff set class |
Syntax hints: wb 103 wal 1282 wmo 1942 class class class wbr 3785 ccnv 4362 wfun 4916 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-io 662 ax-5 1376 ax-7 1377 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-8 1435 ax-10 1436 ax-11 1437 ax-i12 1438 ax-bndl 1439 ax-4 1440 ax-14 1445 ax-17 1459 ax-i9 1463 ax-ial 1467 ax-i5r 1468 ax-ext 2063 ax-sep 3896 ax-pow 3948 ax-pr 3964 |
This theorem depends on definitions: df-bi 115 df-3an 921 df-tru 1287 df-nf 1390 df-sb 1686 df-eu 1944 df-mo 1945 df-clab 2068 df-cleq 2074 df-clel 2077 df-nfc 2208 df-ral 2353 df-rex 2354 df-v 2603 df-un 2977 df-in 2979 df-ss 2986 df-pw 3384 df-sn 3404 df-pr 3405 df-op 3407 df-br 3786 df-opab 3840 df-id 4048 df-xp 4369 df-rel 4370 df-cnv 4371 df-co 4372 df-fun 4924 |
This theorem is referenced by: svrelfun 4984 fun11 4986 |
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