Metamath Proof Explorer


Theorem uzp1

Description: Choices for an element of an upper interval of integers. (Contributed by Jeff Madsen, 2-Sep-2009)

Ref Expression
Assertion uzp1 NMN=MNM+1

Proof

Step Hyp Ref Expression
1 uzm1 NMN=MN1M
2 eluzp1p1 N1MN-1+1M+1
3 eluzelcn NMN
4 ax-1cn 1
5 npcan N1N-1+1=N
6 3 4 5 sylancl NMN-1+1=N
7 6 eleq1d NMN-1+1M+1NM+1
8 2 7 imbitrid NMN1MNM+1
9 8 orim2d NMN=MN1MN=MNM+1
10 1 9 mpd NMN=MNM+1