Definition df-nul 3225

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 3226. (Contributed by NM, 5-Aug-1993.)

Assertion

Ref	Expression
df-nul	⊢ ∅ = (V ∖ V)

Detailed syntax breakdown of Definition df-nul

Step	Hyp	Ref	Expression
1		c0 3224	. 2 class ∅
2		cvv 2557	. . 3 class V
3	2, 2	cdif 2914	. 2 class (V ∖ V)
4	1, 3	wceq 1243	1 wff ∅ = (V ∖ V)

This definition is referenced by:  dfnul2  3226  noel  3228  bdcnulALT  9986