Metamath Proof Explorer


Theorem sspsstri

Description: Two ways of stating trichotomy with respect to inclusion. (Contributed by NM, 12-Aug-2004)

Ref Expression
Assertion sspsstri ABBAABA=BBA

Proof

Step Hyp Ref Expression
1 or32 ABBAA=BABA=BBA
2 sspss ABABA=B
3 sspss BABAB=A
4 eqcom B=AA=B
5 4 orbi2i BAB=ABAA=B
6 3 5 bitri BABAA=B
7 2 6 orbi12i ABBAABA=BBAA=B
8 orordir ABBAA=BABA=BBAA=B
9 7 8 bitr4i ABBAABBAA=B
10 df-3or ABA=BBAABA=BBA
11 1 9 10 3bitr4i ABBAABA=BBA