Description: The exponential function on the reals determines an isomorphism from reals onto positive reals. (Contributed by Steve Rodriguez, 25-Nov-2007) (Revised by Mario Carneiro, 11-Mar-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | reefiso | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | reeff1o | |
|
2 | eflt | |
|
3 | fvres | |
|
4 | fvres | |
|
5 | 3 4 | breqan12d | |
6 | 2 5 | bitr4d | |
7 | 6 | rgen2 | |
8 | df-isom | |
|
9 | 1 7 8 | mpbir2an | |