Metamath Proof Explorer

Theorem bnj105

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

Ref Expression
Assertion bnj105 
|- 1o e. _V

Proof

Step Hyp Ref Expression
1 df1o2 
 |-  1o = { (/) }
2 p0ex 
 |-  { (/) } e. _V
3 1 2 eqeltri 
 |-  1o e. _V