Step |
Hyp |
Ref |
Expression |
1 |
|
addscl |
|
2 |
1
|
negsidd |
|
3 |
|
negsid |
|
4 |
|
negsid |
|
5 |
3 4
|
oveqan12d |
|
6 |
|
0sno |
|
7 |
|
addslid |
|
8 |
6 7
|
ax-mp |
|
9 |
5 8
|
eqtr2di |
|
10 |
|
simpl |
|
11 |
10
|
negscld |
|
12 |
|
simpr |
|
13 |
12
|
negscld |
|
14 |
10 11 12 13
|
adds4d |
|
15 |
2 9 14
|
3eqtrd |
|
16 |
1
|
negscld |
|
17 |
|
negscl |
|
18 |
|
negscl |
|
19 |
|
addscl |
|
20 |
17 18 19
|
syl2an |
|
21 |
16 20 1
|
addscan1d |
|
22 |
15 21
|
mpbid |
|