Metamath Proof Explorer


Theorem 0sald

Description: The empty set belongs to every sigma-algebra. (Contributed by Glauco Siliprandi, 26-Jun-2021)

Ref Expression
Hypothesis 0sald.1 φ S SAlg
Assertion 0sald φ S

Proof

Step Hyp Ref Expression
1 0sald.1 φ S SAlg
2 0sal S SAlg S
3 1 2 syl φ S