Description: Alternate definition of well-founded relation. (Contributed by Scott Fenton, 2-Feb-2011)
Ref | Expression | ||
---|---|---|---|
Assertion | dffr4 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dffr3 | |
|
2 | df-pred | |
|
3 | 2 | eqeq1i | |
4 | 3 | rexbii | |
5 | 4 | imbi2i | |
6 | 5 | albii | |
7 | 1 6 | bitr4i | |