Description: Variable substitution for the at-most-one quantifier. Usage of this theorem is discouraged because it depends on ax-13 . (Contributed by Alexander van der Vekens, 17-Jun-2017) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Hypothesis | sb8eu.1 | ||
Assertion | sb8mo |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sb8eu.1 | ||
2 | 1 | sb8e | |
3 | 1 | sb8eu | |
4 | 2 3 | imbi12i | |
5 | moeu | ||
6 | moeu | ||
7 | 4 5 6 | 3bitr4i |