Definition df-nul 2278

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 2279.

Assertion

Ref	Expression
df-nul	|- (/) = (V \ V)

Detailed syntax breakdown of Definition df-nul

Step	Hyp	Ref	Expression
1		c0 2277	. 2 class (/)
2		cvv 1808	. . 3 class V
3	2, 2	cdif 2041	. 2 class (V \ V)
4	1, 3	wceq 955	1 wff (/) = (V \ V)

This definition is referenced by:  dfnul2 2279

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