Step |
Hyp |
Ref |
Expression |
1 |
|
dnibndlem8.1 |
|
2 |
|
halfre |
|
3 |
2
|
a1i |
|
4 |
1 3
|
jca |
|
5 |
|
simpl |
|
6 |
2
|
a1i |
|
7 |
5 6
|
readdcld |
|
8 |
4 7
|
syl |
|
9 |
|
reflcl |
|
10 |
8 9
|
syl |
|
11 |
1 10
|
resubcld |
|
12 |
1
|
dnicld1 |
|
13 |
11
|
leabsd |
|
14 |
1
|
recnd |
|
15 |
10
|
recnd |
|
16 |
14 15
|
abssubd |
|
17 |
13 16
|
breqtrd |
|
18 |
11 12 3 17
|
lesub2dd |
|
19 |
3
|
recnd |
|
20 |
19 14 15
|
subsub3d |
|
21 |
19 15
|
addcomd |
|
22 |
21
|
oveq1d |
|
23 |
20 22
|
eqtrd |
|
24 |
18 23
|
breqtrd |
|