Metamath Proof Explorer


Theorem mndbn0

Description: The base set of a monoid is not empty. Statement in Lang p. 3. (Contributed by AV, 29-Dec-2023)

Ref Expression
Hypothesis mndbn0.b B=BaseG
Assertion mndbn0 GMndB

Proof

Step Hyp Ref Expression
1 mndbn0.b B=BaseG
2 eqid 0G=0G
3 1 2 mndidcl GMnd0GB
4 3 ne0d GMndB