author nipkow Tue, 08 Dec 2020 17:40:43 +0100 changeset 72851 f0fa51227a23 parent 72850 4cb480334f48 child 72852 7568a54aadcd
tuned
```--- a/src/HOL/Data_Structures/RBT_Set.thy	Mon Dec 07 22:28:41 2020 +0100
+++ b/src/HOL/Data_Structures/RBT_Set.thy	Tue Dec 08 17:40:43 2020 +0100
@@ -265,13 +265,13 @@

lemma inv_del: "\<lbrakk> invh t; invc t \<rbrakk> \<Longrightarrow>
invh (del x t) \<and>
-   (color t = Red \<and> bheight (del x t) = bheight t \<and> invc (del x t) \<or>
-    color t = Black \<and> bheight (del x t) = bheight t - 1 \<and> invc2 (del x t))"
+   (color t = Red \<longrightarrow> bheight (del x t) = bheight t \<and> invc (del x t)) \<and>
+   (color t = Black \<longrightarrow> bheight (del x t) = bheight t - 1 \<and> invc2 (del x t))"
by(induct x t rule: del.induct)
(auto simp: inv_baldL inv_baldR inv_join dest!: neq_LeafD)

theorem rbt_delete: "rbt t \<Longrightarrow> rbt (delete x t)"
-by (metis delete_def rbt_def color_paint_Black inv_del invc2I invh_paint)
+by (metis delete_def rbt_def color_paint_Black inv_del invh_paint)

text \<open>Overall correctness:\<close>
```