Metamath Proof Explorer


Theorem fzon0

Description: A half-open integer interval is nonempty iff it contains its left endpoint. (Contributed by Mario Carneiro, 29-Sep-2015)

Ref Expression
Assertion fzon0 M ..^ N M M ..^ N

Proof

Step Hyp Ref Expression
1 n0 M ..^ N x x M ..^ N
2 elfzolt3b x M ..^ N M M ..^ N
3 2 exlimiv x x M ..^ N M M ..^ N
4 1 3 sylbi M ..^ N M M ..^ N
5 ne0i M M ..^ N M ..^ N
6 4 5 impbii M ..^ N M M ..^ N