Description: Exchange the first endpoint in betweenness. Left-hand side of Theorem 3.6 of Schwabhauser p. 30. (Contributed by Scott Fenton, 12-Jun-2013)
Ref | Expression | ||
---|---|---|---|
Assertion | btwnexch3 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simp1 | |
|
2 | simp3l | |
|
3 | simp2l | |
|
4 | simp3r | |
|
5 | btwncom | |
|
6 | 1 2 3 4 5 | syl13anc | |
7 | simp2r | |
|
8 | btwncom | |
|
9 | 1 7 3 2 8 | syl13anc | |
10 | 6 9 | anbi12d | |
11 | axpasch | |
|
12 | 1 4 2 3 2 7 11 | syl132anc | |
13 | 10 12 | sylbid | |
14 | 13 | ancomsd | |
15 | simpl1 | |
|
16 | simpr | |
|
17 | simpl3l | |
|
18 | axbtwnid | |
|
19 | 15 16 17 18 | syl3anc | |
20 | breq1 | |
|
21 | 20 | biimpd | |
22 | 19 21 | syl6 | |
23 | 22 | impd | |
24 | 23 | rexlimdva | |
25 | 14 24 | syld | |