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| Description: The null set is a subset of any class. Part of Exercise 1 of [TakeutiZaring] p. 22. |
| Ref | Expression |
|---|---|
| 0ss |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | noel 2274 |
. . 3
| |
| 2 | 1 | pm2.21i 77 |
. 2
|
| 3 | 2 | ssriv 2059 |
1
|
| Colors of variables: wff set class |
| Syntax hints: |
| This theorem is referenced by: ss0b 2292 0pss 2298 pwpw0 2460 snsspr 2461 sssn 2464 sspr 2466 uni0 2515 int0el 2551 tr0 2681 0elpw 2726 on0eqelt 3114 rel0 3262 0ima 3405 dmxpss 3459 rnxpss 3460 fun0 3530 f0 3641 oaword1 4170 oaword2 4171 omwordri 4187 oewordri 4203 oeworde 4204 mapsspw 4325 map0e 4326 0dom 4444 fodomr 4463 php 4493 inf3lemd 4584 inf3lem1 4585 r1val1 4630 alephgeom 4854 cfub 4880 cf0 4882 cflecard 4884 cfle 4885 xrsup0 6044 ioossre 6328 uzssz 6362 infxpidmlem8 7502 infmap2 7523 0opnt 7543 0cld 7620 cls0 7651 chocnul 9207 span0 9380 chsup0 9386 clsrebb 10380 |
| This theorem was proved from axioms: ax-1 4 ax-2 5 ax-3 6 ax-mp 7 ax-7 959 ax-gen 960 ax-8 961 ax-10 963 ax-12 965 ax-17 968 ax-4 970 ax-5o 972 ax-6o 975 ax-9o 1119 ax-10o 1136 ax-16 1206 ax-11o 1213 ax-ext 1452 |
| This theorem depends on definitions: df-bi 147 df-or 224 df-an 225 df-ex 978 df-sb 1168 df-clab 1457 df-cleq 1462 df-clel 1465 df-v 1803 df-dif 2039 df-in 2041 df-ss 2043 df-nul 2271 |