Description: If A is a member of the filter, then the filter truncated to A is a subset of the original filter. (Contributed by Mario Carneiro, 15-Oct-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | trfilss | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | restval | |
|
2 | filin | |
|
3 | 2 | 3expa | |
4 | 3 | an32s | |
5 | 4 | fmpttd | |
6 | 5 | frnd | |
7 | 1 6 | eqsstrd | |