This is an inofficial mirror of http://metamath.tirix.org for personal testing of a visualizer extension only.

Metamath Proof Explorer


Theorem br0

Description: The empty binary relation never holds. (Contributed by NM, 23-Aug-2018)

Ref Expression
Assertion br0 ¬ A B

Proof

Step Hyp Ref Expression
1 noel ¬ A B
2 df-br A B A B
3 1 2 mtbir ¬ A B