Description: The sum of two positive operators is positive. Exercise 1(i) of Retherford p. 49. (Contributed by NM, 25-Jul-2006) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | leopadd | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | r19.26 | |
|
2 | hmopre | |
|
3 | hmopre | |
|
4 | addge0 | |
|
5 | 4 | ex | |
6 | 2 3 5 | syl2an | |
7 | 6 | anandirs | |
8 | hmopf | |
|
9 | hmopf | |
|
10 | 8 9 | anim12i | |
11 | hosval | |
|
12 | 11 | oveq1d | |
13 | 12 | 3expa | |
14 | ffvelcdm | |
|
15 | 14 | adantlr | |
16 | ffvelcdm | |
|
17 | 16 | adantll | |
18 | simpr | |
|
19 | ax-his2 | |
|
20 | 15 17 18 19 | syl3anc | |
21 | 13 20 | eqtrd | |
22 | 10 21 | sylan | |
23 | 22 | breq2d | |
24 | 7 23 | sylibrd | |
25 | 24 | ralimdva | |
26 | 1 25 | biimtrrid | |
27 | leoppos | |
|
28 | leoppos | |
|
29 | 27 28 | bi2anan9 | |
30 | hmops | |
|
31 | leoppos | |
|
32 | 30 31 | syl | |
33 | 26 29 32 | 3imtr4d | |
34 | 33 | imp | |