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| Description: The double converse of a function is a function. |
| Ref | Expression |
|---|---|
| funcnvcnv |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cnvcnvss 3488 |
. 2
| |
| 2 | funss 3534 |
. 2
| |
| 3 | 1, 2 | ax-mp 7 |
1
|
| Colors of variables: wff set class |
| Syntax hints: |
| This theorem is referenced by: funcnvres2 3570 f1ocnv 3701 sbthlem8 4454 iscncl 7770 |
| This theorem was proved from axioms: ax-1 4 ax-2 5 ax-3 6 ax-mp 7 ax-7 962 ax-gen 963 ax-8 964 ax-10 966 ax-11 967 ax-12 968 ax-13 969 ax-14 970 ax-17 971 ax-4 973 ax-5o 975 ax-6o 978 ax-9o 1123 ax-10o 1140 ax-16 1210 ax-11o 1218 ax-ext 1459 ax-sep 2703 ax-pow 2742 ax-pr 2779 |
| This theorem depends on definitions: df-bi 147 df-or 224 df-an 225 df-ex 981 df-sb 1172 df-eu 1382 df-mo 1383 df-clab 1464 df-cleq 1469 df-clel 1472 df-ne 1587 df-v 1812 df-dif 2049 df-un 2050 df-in 2051 df-ss 2053 df-nul 2281 df-pw 2402 df-sn 2412 df-pr 2413 df-op 2416 df-br 2620 df-opab 2667 df-id 2835 df-xp 3184 df-rel 3185 df-cnv 3186 df-co 3187 df-fun 3192 |