Description: Conditions for the trace of a filter base F to be a filter base. (Contributed by Mario Carneiro, 13-Oct-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | trfbas | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | trfbas2 | |
|
2 | elfvdm | |
|
3 | ssexg | |
|
4 | 3 | ancoms | |
5 | 2 4 | sylan | |
6 | elrest | |
|
7 | 5 6 | syldan | |
8 | 7 | notbid | |
9 | nesym | |
|
10 | 9 | ralbii | |
11 | ralnex | |
|
12 | 10 11 | bitri | |
13 | 8 12 | bitr4di | |
14 | 1 13 | bitrd | |