Metamath Proof Explorer


Theorem brcoi

Description: Ordered pair membership in a composition. (Contributed by BJ, 25-Oct-2026)

Ref Expression
Hypotheses brcoi.1
|- X e. _V
brcoi.2
|- Y e. _V
brcoi.3
|- Z e. _V
Assertion brcoi
|- ( ( X R Y /\ Y S Z ) -> X ( S o. R ) Z )

Proof

Step Hyp Ref Expression
1 brcoi.1
 |-  X e. _V
2 brcoi.2
 |-  Y e. _V
3 brcoi.3
 |-  Z e. _V
4 1 3 2 3pm3.2i
 |-  ( X e. _V /\ Z e. _V /\ Y e. _V )
5 brcogw
 |-  ( ( ( X e. _V /\ Z e. _V /\ Y e. _V ) /\ ( X R Y /\ Y S Z ) ) -> X ( S o. R ) Z )
6 4 5 mpan
 |-  ( ( X R Y /\ Y S Z ) -> X ( S o. R ) Z )