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Mirrors > Home > MPE Home > Th. List > n0snor2el | Structured version Visualization version Unicode version |
Description: A nonempty set is either a singleton or contains at least two different elements. (Contributed by AV, 20-Sep-2020.) |
Ref | Expression |
---|---|
n0snor2el |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | issn 4363 | . . . 4 | |
2 | 1 | olcd 408 | . . 3 |
3 | 2 | a1d 25 | . 2 |
4 | df-ne 2795 | . . . . . . 7 | |
5 | 4 | rexbii 3041 | . . . . . 6 |
6 | rexnal 2995 | . . . . . 6 | |
7 | 5, 6 | bitri 264 | . . . . 5 |
8 | 7 | ralbii 2980 | . . . 4 |
9 | ralnex 2992 | . . . 4 | |
10 | 8, 9 | bitri 264 | . . 3 |
11 | neeq1 2856 | . . . . . . . 8 | |
12 | 11 | rexbidv 3052 | . . . . . . 7 |
13 | 12 | rspccva 3308 | . . . . . 6 |
14 | 13 | reximdva0 3933 | . . . . 5 |
15 | 14 | orcd 407 | . . . 4 |
16 | 15 | ex 450 | . . 3 |
17 | 10, 16 | sylbir 225 | . 2 |
18 | 3, 17 | pm2.61i 176 | 1 |
Colors of variables: wff setvar class |
Syntax hints: wn 3 wi 4 wo 383 wa 384 wceq 1483 wex 1704 wne 2794 wral 2912 wrex 2913 c0 3915 csn 4177 |
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 |
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-clab 2609 df-cleq 2615 df-clel 2618 df-nfc 2753 df-ne 2795 df-ral 2917 df-rex 2918 df-v 3202 df-dif 3577 df-in 3581 df-ss 3588 df-nul 3916 df-sn 4178 |
This theorem is referenced by: iunopeqop 4981 |
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