Metamath Proof Explorer


Theorem snmbl

Description: A singleton is measurable. (Contributed by Glauco Siliprandi, 11-Dec-2019)

Ref Expression
Assertion snmbl
|- ( A e. RR -> { A } e. dom vol )

Proof

Step Hyp Ref Expression
1 snssi
 |-  ( A e. RR -> { A } C_ RR )
2 ovolsn
 |-  ( A e. RR -> ( vol* ` { A } ) = 0 )
3 nulmbl
 |-  ( ( { A } C_ RR /\ ( vol* ` { A } ) = 0 ) -> { A } e. dom vol )
4 1 2 3 syl2anc
 |-  ( A e. RR -> { A } e. dom vol )