Description: Obsolete version of sban as of 13-Aug-2023. Conjunction inside and outside of a substitution are equivalent. (Contributed by NM, 14-May-1993) (New usage is discouraged.) (Proof modification is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | sbanOLD |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sbn | ||
2 | sbim | ||
3 | sbn | ||
4 | 3 | imbi2i | |
5 | 2 4 | bitri | |
6 | 1 5 | xchbinx | |
7 | df-an | ||
8 | 7 | sbbii | |
9 | df-an | ||
10 | 6 8 9 | 3bitr4i |