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Definition df-nul 3219
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 3220. (Contributed by NM, 5-Aug-1993.)
Assertion
Ref Expression
df-nul  (/)  _V  \  _V

Detailed syntax breakdown of Definition df-nul
StepHypRef Expression
1 c0 3218 . 2  (/)
2 cvv 2551 . . 3  _V
32, 2cdif 2908 . 2  _V 
\  _V
41, 3wceq 1242 1  (/)  _V  \  _V
Colors of variables: wff set class
This definition is referenced by:  dfnul2  3220  noel  3222  bdcnulALT  9321
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