Metamath Proof Explorer


Definition df-ioo

Description: Define the set of open intervals of extended reals. (Contributed by NM, 24-Dec-2006)

Ref Expression
Assertion df-ioo .=x*,y*z*|x<zz<y

Detailed syntax breakdown

Step Hyp Ref Expression
0 cioo class.
1 vx setvarx
2 cxr class*
3 vy setvary
4 vz setvarz
5 1 cv setvarx
6 clt class<
7 4 cv setvarz
8 5 7 6 wbr wffx<z
9 3 cv setvary
10 7 9 6 wbr wffz<y
11 8 10 wa wffx<zz<y
12 11 4 2 crab classz*|x<zz<y
13 1 3 2 2 12 cmpo classx*,y*z*|x<zz<y
14 0 13 wceq wff.=x*,y*z*|x<zz<y