Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > MPE Home > Th. List > df-nul | Structured version Visualization version Unicode version |
Description: Define the empty set. Special case of Exercise 4.10(o) of [Mendelson] p. 231. For a more traditional definition, but requiring a dummy variable, see dfnul2 3917. (Contributed by NM, 17-Jun-1993.) |
Ref | Expression |
---|---|
df-nul |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | c0 3915 | . 2 | |
2 | cvv 3200 | . . 3 | |
3 | 2, 2 | cdif 3571 | . 2 |
4 | 1, 3 | wceq 1483 | 1 |
Colors of variables: wff setvar class |
This definition is referenced by: dfnul2 3917 noel 3919 |
Copyright terms: Public domain | W3C validator |