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Mirrors > Home > ILE Home > Th. List > sspwb | Unicode version |
Description: Classes are subclasses if and only if their power classes are subclasses. Exercise 18 of [TakeutiZaring] p. 18. (Contributed by NM, 13-Oct-1996.) |
Ref | Expression |
---|---|
sspwb |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sstr2 3099 | . . . . 5 | |
2 | 1 | com12 30 | . . . 4 |
3 | vex 2684 | . . . . 5 | |
4 | 3 | elpw 3511 | . . . 4 |
5 | 3 | elpw 3511 | . . . 4 |
6 | 2, 4, 5 | 3imtr4g 204 | . . 3 |
7 | 6 | ssrdv 3098 | . 2 |
8 | ssel 3086 | . . . 4 | |
9 | 3 | snex 4104 | . . . . . 6 |
10 | 9 | elpw 3511 | . . . . 5 |
11 | 3 | snss 3644 | . . . . 5 |
12 | 10, 11 | bitr4i 186 | . . . 4 |
13 | 9 | elpw 3511 | . . . . 5 |
14 | 3 | snss 3644 | . . . . 5 |
15 | 13, 14 | bitr4i 186 | . . . 4 |
16 | 8, 12, 15 | 3imtr3g 203 | . . 3 |
17 | 16 | ssrdv 3098 | . 2 |
18 | 7, 17 | impbii 125 | 1 |
Colors of variables: wff set class |
Syntax hints: wb 104 wcel 1480 wss 3066 cpw 3505 csn 3522 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-14 1492 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2119 ax-sep 4041 ax-pow 4093 |
This theorem depends on definitions: df-bi 116 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2124 df-cleq 2130 df-clel 2133 df-nfc 2268 df-v 2683 df-in 3072 df-ss 3079 df-pw 3507 df-sn 3528 |
This theorem is referenced by: pwel 4135 ssextss 4137 pweqb 4140 fiss 6858 ntrss 12277 |
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