intros st p.
generalize dependent st.
induction p as [ | d ds].
+ intros.
exfalso.
eapply Pref.
- inversion Corr as [Vary_In In_Vary Pref']; clear Corr.
eapply Vary_In; eassumption.
- instantiate (1 := []); instantiate (1 := p'); rewrite app_nil_r; auto.
+ intros st f l Corr Pref p' seed VarySome.
destruct st; destruct d; simpl; auto.
* exfalso. apply corrUndefEmpty in Corr. subst. inversion VarySome.
* exfalso. apply corrUndefEmpty in Corr. subst. inversion VarySome.
* exfalso.
apply corrEmptyLeaf in Corr; inversion Corr; subst; clear Corr.
eapply Pref.
instantiate (1 := []); left; auto.
instantiate (1:= Left :: ds). instantiate (1 := []). rewrite app_nil_r; simpl; auto.
* exfalso.
apply corrEmptyLeaf in Corr; inversion Corr; subst; clear Corr.
eapply Pref.
instantiate (1 := []); left; auto.
instantiate (1:= Right :: ds). instantiate (1 := []). rewrite app_nil_r; simpl; auto.
* destruct p'.
- simpl in VarySome. inversion VarySome.
- destruct s.
+ apply IHds; auto.
+ auto.
* destruct p'.
- simpl in VarySome; inversion VarySome.
- destruct s.
+ auto.
+ apply IHds; auto.
Qed.

Lemma addToTreeCorrect3 : forall (st : SeedTree) (p : SplitPath)
(f : SplitPath -> RandomSeed)
(l : list SplitPath) (Corr : correspondingSeedTree l f st)
(Pref : forall p', In p' l -> (forall p1 p2, p ++ p1 = p' ++ p2 -> False)),
forall p' seed, varySeed' (addToTree st p f l Corr Pref) p' = Some seed ->
p = p' \/ varySeed' st p' = Some seed.