Description: The index variable in an indexed Cartesian product is not free. (Contributed by Jeff Madsen, 19-Jun-2011) (Revised by Mario Carneiro, 15-Oct-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | nfixp1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-ixp | |
|
2 | nfcv | |
|
3 | nfab1 | |
|
4 | 2 3 | nffn | |
5 | nfra1 | |
|
6 | 4 5 | nfan | |
7 | 6 | nfab | |
8 | 1 7 | nfcxfr | |