Step |
Hyp |
Ref |
Expression |
1 |
|
dnibndlem7.1 |
|
2 |
|
halfre |
|
3 |
2
|
a1i |
|
4 |
1 3
|
jca |
|
5 |
|
readdcl |
|
6 |
4 5
|
syl |
|
7 |
|
reflcl |
|
8 |
6 7
|
syl |
|
9 |
8 1
|
jca |
|
10 |
|
resubcl |
|
11 |
9 10
|
syl |
|
12 |
1
|
dnicld1 |
|
13 |
11
|
leabsd |
|
14 |
11 12 3 13
|
lesub2dd |
|
15 |
3
|
recnd |
|
16 |
8
|
recnd |
|
17 |
1
|
recnd |
|
18 |
15 16 17
|
subsub3d |
|
19 |
15 17
|
addcomd |
|
20 |
19
|
oveq1d |
|
21 |
17 16 15
|
subsub3d |
|
22 |
21
|
eqcomd |
|
23 |
18 20 22
|
3eqtrd |
|
24 |
14 23
|
breqtrd |
|