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Mirrors > Home > MPE Home > Th. List > 0ntop | Structured version Visualization version Unicode version |
Description: The empty set is not a topology. (Contributed by FL, 1-Jun-2008.) |
Ref | Expression |
---|---|
0ntop |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | noel 3919 | . 2 | |
2 | 0opn 20709 | . 2 | |
3 | 1, 2 | mto 188 | 1 |
Colors of variables: wff setvar class |
Syntax hints: wn 3 wcel 1990 c0 3915 ctop 20698 |
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 ax-sep 4781 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 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-ral 2917 df-rex 2918 df-v 3202 df-dif 3577 df-in 3581 df-ss 3588 df-nul 3916 df-pw 4160 df-sn 4178 df-uni 4437 df-top 20699 |
This theorem is referenced by: istps 20738 ordcmp 32446 onint1 32448 kelac1 37633 |
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