-
-Definition pivotContext {T} a b c : @Arrange T ((a,,b),,c) ((a,,c),,b) :=
- RComp (RComp (RCossa _ _ _) (RLeft a (RExch c b))) (RAssoc _ _ _).
-
-Definition pivotContext' {T} a b c : @Arrange T (a,,(b,,c)) (b,,(a,,c)) :=
- RComp (RComp (RAssoc _ _ _) (RRight c (RExch b a))) (RCossa _ _ _).
-
-Definition copyAndPivotContext {T} a b c : @Arrange T ((a,,b),,(c,,b)) ((a,,c),,b).
- eapply RComp; [ idtac | apply (RLeft (a,,c) (RCont b)) ].
- eapply RComp; [ idtac | apply RCossa ].
- eapply RComp; [ idtac | apply (RRight b (pivotContext a b c)) ].
- apply RAssoc.
- Defined.
-