Description: Two elements are the same distance apart as their inverses. (Contributed by Mario Carneiro, 4-Oct-2015)
Ref | Expression | ||
---|---|---|---|
Hypotheses | ngpinvds.x | |
|
ngpinvds.i | |
||
ngpinvds.d | |
||
Assertion | ngpinvds | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ngpinvds.x | |
|
2 | ngpinvds.i | |
|
3 | ngpinvds.d | |
|
4 | eqid | |
|
5 | simplr | |
|
6 | simprr | |
|
7 | simprl | |
|
8 | 1 4 2 5 6 7 | ablsub2inv | |
9 | 8 | fveq2d | |
10 | simpll | |
|
11 | ngpgrp | |
|
12 | 10 11 | syl | |
13 | 1 2 | grpinvcl | |
14 | 12 7 13 | syl2anc | |
15 | 1 2 | grpinvcl | |
16 | 12 6 15 | syl2anc | |
17 | eqid | |
|
18 | 17 1 4 3 | ngpdsr | |
19 | 10 14 16 18 | syl3anc | |
20 | 17 1 4 3 | ngpds | |
21 | 10 7 6 20 | syl3anc | |
22 | 9 19 21 | 3eqtr4d | |