Metamath Proof Explorer


Theorem grpbn0

Description: The base set of a group is not empty. (Contributed by Szymon Jaroszewicz, 3-Apr-2007)

Ref Expression
Hypothesis grpbn0.b ⊢ B = Base G
Assertion grpbn0 ⊢ G ∈ Grp → B ≠ ∅

Proof

Step Hyp Ref Expression
1 grpbn0.b ⊢ B = Base G
2 eqid ⊢ 0 G = 0 G
3 1 2 grpidcl ⊢ G ∈ Grp → 0 G ∈ B
4 3 ne0d ⊢ G ∈ Grp → B ≠ ∅