diff --git a/src/HOL/Analysis/Affine.thy b/src/HOL/Analysis/Affine.thy
--- a/src/HOL/Analysis/Affine.thy
+++ b/src/HOL/Analysis/Affine.thy
@@ -1,1655 +1,1657 @@
 section "Affine Sets"
 
 theory Affine
 imports Linear_Algebra
 begin
 
 lemma if_smult: "(if P then x else (y::real)) *\<^sub>R v = (if P then x *\<^sub>R v else y *\<^sub>R v)"
   by (fact if_distrib)
 
 lemma sum_delta_notmem:
   assumes "x \<notin> s"
   shows "sum (\<lambda>y. if (y = x) then P x else Q y) s = sum Q s"
     and "sum (\<lambda>y. if (x = y) then P x else Q y) s = sum Q s"
     and "sum (\<lambda>y. if (y = x) then P y else Q y) s = sum Q s"
     and "sum (\<lambda>y. if (x = y) then P y else Q y) s = sum Q s"
   apply (rule_tac [!] sum.cong)
   using assms
   apply auto
   done
 
 lemmas independent_finite = independent_imp_finite
 
 lemma span_substd_basis:
   assumes d: "d \<subseteq> Basis"
   shows "span d = {x. \<forall>i\<in>Basis. i \<notin> d \<longrightarrow> x\<bullet>i = 0}"
   (is "_ = ?B")
 proof -
   have "d \<subseteq> ?B"
     using d by (auto simp: inner_Basis)
   moreover have s: "subspace ?B"
     using subspace_substandard[of "\<lambda>i. i \<notin> d"] .
   ultimately have "span d \<subseteq> ?B"
     using span_mono[of d "?B"] span_eq_iff[of "?B"] by blast
   moreover have *: "card d \<le> dim (span d)"
     using independent_card_le_dim[of d "span d"] independent_substdbasis[OF assms]
       span_superset[of d]
     by auto
   moreover from * have "dim ?B \<le> dim (span d)"
     using dim_substandard[OF assms] by auto
   ultimately show ?thesis
     using s subspace_dim_equal[of "span d" "?B"] subspace_span[of d] by auto
 qed
 
 lemma basis_to_substdbasis_subspace_isomorphism:
   fixes B :: "'a::euclidean_space set"
   assumes "independent B"
   shows "\<exists>f d::'a set. card d = card B \<and> linear f \<and> f ` B = d \<and>
     f ` span B = {x. \<forall>i\<in>Basis. i \<notin> d \<longrightarrow> x \<bullet> i = 0} \<and> inj_on f (span B) \<and> d \<subseteq> Basis"
 proof -
   have B: "card B = dim B"
     using dim_unique[of B B "card B"] assms span_superset[of B] by auto
   have "dim B \<le> card (Basis :: 'a set)"
     using dim_subset_UNIV[of B] by simp
   from ex_card[OF this] obtain d :: "'a set" where d: "d \<subseteq> Basis" and t: "card d = dim B"
     by auto
   let ?t = "{x::'a::euclidean_space. \<forall>i\<in>Basis. i \<notin> d \<longrightarrow> x\<bullet>i = 0}"
   have "\<exists>f. linear f \<and> f ` B = d \<and> f ` span B = ?t \<and> inj_on f (span B)"
   proof (intro basis_to_basis_subspace_isomorphism subspace_span subspace_substandard span_superset)
     show "d \<subseteq> {x. \<forall>i\<in>Basis. i \<notin> d \<longrightarrow> x \<bullet> i = 0}"
       using d inner_not_same_Basis by blast
   qed (auto simp: span_substd_basis independent_substdbasis dim_substandard d t B assms)
   with t \<open>card B = dim B\<close> d show ?thesis by auto
 qed
 
 subsection \<open>Affine set and affine hull\<close>
 
 definition\<^marker>\<open>tag important\<close> affine :: "'a::real_vector set \<Rightarrow> bool"
   where "affine s \<longleftrightarrow> (\<forall>x\<in>s. \<forall>y\<in>s. \<forall>u v. u + v = 1 \<longrightarrow> u *\<^sub>R x + v *\<^sub>R y \<in> s)"
 
 lemma affine_alt: "affine s \<longleftrightarrow> (\<forall>x\<in>s. \<forall>y\<in>s. \<forall>u::real. (1 - u) *\<^sub>R x + u *\<^sub>R y \<in> s)"
   unfolding affine_def by (metis eq_diff_eq')
 
 lemma affine_empty [iff]: "affine {}"
   unfolding affine_def by auto
 
 lemma affine_sing [iff]: "affine {x}"
   unfolding affine_alt by (auto simp: scaleR_left_distrib [symmetric])
 
 lemma affine_UNIV [iff]: "affine UNIV"
   unfolding affine_def by auto
 
 lemma affine_Inter [intro]: "(\<And>s. s\<in>f \<Longrightarrow> affine s) \<Longrightarrow> affine (\<Inter>f)"
   unfolding affine_def by auto
 
 lemma affine_Int[intro]: "affine s \<Longrightarrow> affine t \<Longrightarrow> affine (s \<inter> t)"
   unfolding affine_def by auto
 
 lemma affine_scaling: "affine s \<Longrightarrow> affine (image (\<lambda>x. c *\<^sub>R x) s)"
   apply (clarsimp simp add: affine_def)
   apply (rule_tac x="u *\<^sub>R x + v *\<^sub>R y" in image_eqI)
   apply (auto simp: algebra_simps)
   done
 
 lemma affine_affine_hull [simp]: "affine(affine hull s)"
   unfolding hull_def
   using affine_Inter[of "{t. affine t \<and> s \<subseteq> t}"] by auto
 
 lemma affine_hull_eq[simp]: "(affine hull s = s) \<longleftrightarrow> affine s"
   by (metis affine_affine_hull hull_same)
 
 lemma affine_hyperplane: "affine {x. a \<bullet> x = b}"
   by (simp add: affine_def algebra_simps) (metis distrib_right mult.left_neutral)
 
 
 subsubsection\<^marker>\<open>tag unimportant\<close> \<open>Some explicit formulations\<close>
 
 text "Formalized by Lars Schewe."
 
 lemma affine:
   fixes V::"'a::real_vector set"
   shows "affine V \<longleftrightarrow>
          (\<forall>S u. finite S \<and> S \<noteq> {} \<and> S \<subseteq> V \<and> sum u S = 1 \<longrightarrow> (\<Sum>x\<in>S. u x *\<^sub>R x) \<in> V)"
 proof -
   have "u *\<^sub>R x + v *\<^sub>R y \<in> V" if "x \<in> V" "y \<in> V" "u + v = (1::real)"
     and *: "\<And>S u. \<lbrakk>finite S; S \<noteq> {}; S \<subseteq> V; sum u S = 1\<rbrakk> \<Longrightarrow> (\<Sum>x\<in>S. u x *\<^sub>R x) \<in> V" for x y u v
   proof (cases "x = y")
     case True
     then show ?thesis
       using that by (metis scaleR_add_left scaleR_one)
   next
     case False
     then show ?thesis
       using that *[of "{x,y}" "\<lambda>w. if w = x then u else v"] by auto
   qed
   moreover have "(\<Sum>x\<in>S. u x *\<^sub>R x) \<in> V"
                 if *: "\<And>x y u v. \<lbrakk>x\<in>V; y\<in>V; u + v = 1\<rbrakk> \<Longrightarrow> u *\<^sub>R x + v *\<^sub>R y \<in> V"
                   and "finite S" "S \<noteq> {}" "S \<subseteq> V" "sum u S = 1" for S u
   proof -
     define n where "n = card S"
     consider "card S = 0" | "card S = 1" | "card S = 2" | "card S > 2" by linarith
     then show "(\<Sum>x\<in>S. u x *\<^sub>R x) \<in> V"
     proof cases
       assume "card S = 1"
       then obtain a where "S={a}"
         by (auto simp: card_Suc_eq)
       then show ?thesis
         using that by simp
     next
       assume "card S = 2"
       then obtain a b where "S = {a, b}"
         by (metis Suc_1 card_1_singletonE card_Suc_eq)
       then show ?thesis
         using *[of a b] that
         by (auto simp: sum_clauses(2))
     next
       assume "card S > 2"
       then show ?thesis using that n_def
       proof (induct n arbitrary: u S)
         case 0
         then show ?case by auto
       next
         case (Suc n u S)
         have "sum u S = card S" if "\<not> (\<exists>x\<in>S. u x \<noteq> 1)"
           using that unfolding card_eq_sum by auto
         with Suc.prems obtain x where "x \<in> S" and x: "u x \<noteq> 1" by force
         have c: "card (S - {x}) = card S - 1"
           by (simp add: Suc.prems(3) \<open>x \<in> S\<close>)
         have "sum u (S - {x}) = 1 - u x"
           by (simp add: Suc.prems sum_diff1 \<open>x \<in> S\<close>)
         with x have eq1: "inverse (1 - u x) * sum u (S - {x}) = 1"
           by auto
         have inV: "(\<Sum>y\<in>S - {x}. (inverse (1 - u x) * u y) *\<^sub>R y) \<in> V"
         proof (cases "card (S - {x}) > 2")
           case True
           then have S: "S - {x} \<noteq> {}" "card (S - {x}) = n"
             using Suc.prems c by force+
           show ?thesis
           proof (rule Suc.hyps)
             show "(\<Sum>a\<in>S - {x}. inverse (1 - u x) * u a) = 1"
               by (auto simp: eq1 sum_distrib_left[symmetric])
           qed (use S Suc.prems True in auto)
         next
           case False
           then have "card (S - {x}) = Suc (Suc 0)"
             using Suc.prems c by auto
           then obtain a b where ab: "(S - {x}) = {a, b}" "a\<noteq>b"
             unfolding card_Suc_eq by auto
           then show ?thesis
             using eq1 \<open>S \<subseteq> V\<close>
             by (auto simp: sum_distrib_left distrib_left intro!: Suc.prems(2)[of a b])
         qed
         have "u x + (1 - u x) = 1 \<Longrightarrow>
           u x *\<^sub>R x + (1 - u x) *\<^sub>R ((\<Sum>y\<in>S - {x}. u y *\<^sub>R y) /\<^sub>R (1 - u x)) \<in> V"
           by (rule Suc.prems) (use \<open>x \<in> S\<close> Suc.prems inV in \<open>auto simp: scaleR_right.sum\<close>)
         moreover have "(\<Sum>a\<in>S. u a *\<^sub>R a) = u x *\<^sub>R x + (\<Sum>a\<in>S - {x}. u a *\<^sub>R a)"
           by (meson Suc.prems(3) sum.remove \<open>x \<in> S\<close>)
         ultimately show "(\<Sum>x\<in>S. u x *\<^sub>R x) \<in> V"
           by (simp add: x)
       qed
     qed (use \<open>S\<noteq>{}\<close> \<open>finite S\<close> in auto)
   qed
   ultimately show ?thesis
     unfolding affine_def by meson
 qed
 
 
 lemma affine_hull_explicit:
   "affine hull p = {y. \<exists>S u. finite S \<and> S \<noteq> {} \<and> S \<subseteq> p \<and> sum u S = 1 \<and> sum (\<lambda>v. u v *\<^sub>R v) S = y}"
   (is "_ = ?rhs")
 proof (rule hull_unique)
   show "p \<subseteq> ?rhs"
   proof (intro subsetI CollectI exI conjI)
     show "\<And>x. sum (\<lambda>z. 1) {x} = 1"
       by auto
   qed auto
   show "?rhs \<subseteq> T" if "p \<subseteq> T" "affine T" for T
     using that unfolding affine by blast
   show "affine ?rhs"
     unfolding affine_def
   proof clarify
     fix u v :: real and sx ux sy uy
     assume uv: "u + v = 1"
       and x: "finite sx" "sx \<noteq> {}" "sx \<subseteq> p" "sum ux sx = (1::real)"
       and y: "finite sy" "sy \<noteq> {}" "sy \<subseteq> p" "sum uy sy = (1::real)" 
     have **: "(sx \<union> sy) \<inter> sx = sx" "(sx \<union> sy) \<inter> sy = sy"
       by auto
     show "\<exists>S w. finite S \<and> S \<noteq> {} \<and> S \<subseteq> p \<and>
         sum w S = 1 \<and> (\<Sum>v\<in>S. w v *\<^sub>R v) = u *\<^sub>R (\<Sum>v\<in>sx. ux v *\<^sub>R v) + v *\<^sub>R (\<Sum>v\<in>sy. uy v *\<^sub>R v)"
     proof (intro exI conjI)
       show "finite (sx \<union> sy)"
         using x y by auto
       show "sum (\<lambda>i. (if i\<in>sx then u * ux i else 0) + (if i\<in>sy then v * uy i else 0)) (sx \<union> sy) = 1"
         using x y uv
         by (simp add: sum_Un sum.distrib sum.inter_restrict[symmetric] sum_distrib_left [symmetric] **)
       have "(\<Sum>i\<in>sx \<union> sy. ((if i \<in> sx then u * ux i else 0) + (if i \<in> sy then v * uy i else 0)) *\<^sub>R i)
           = (\<Sum>i\<in>sx. (u * ux i) *\<^sub>R i) + (\<Sum>i\<in>sy. (v * uy i) *\<^sub>R i)"
         using x y
         unfolding scaleR_left_distrib scaleR_zero_left if_smult
         by (simp add: sum_Un sum.distrib sum.inter_restrict[symmetric]  **)
       also have "\<dots> = u *\<^sub>R (\<Sum>v\<in>sx. ux v *\<^sub>R v) + v *\<^sub>R (\<Sum>v\<in>sy. uy v *\<^sub>R v)"
         unfolding scaleR_scaleR[symmetric] scaleR_right.sum [symmetric] by blast
       finally show "(\<Sum>i\<in>sx \<union> sy. ((if i \<in> sx then u * ux i else 0) + (if i \<in> sy then v * uy i else 0)) *\<^sub>R i) 
                   = u *\<^sub>R (\<Sum>v\<in>sx. ux v *\<^sub>R v) + v *\<^sub>R (\<Sum>v\<in>sy. uy v *\<^sub>R v)" .
     qed (use x y in auto)
   qed
 qed
 
 lemma affine_hull_finite:
   assumes "finite S"
   shows "affine hull S = {y. \<exists>u. sum u S = 1 \<and> sum (\<lambda>v. u v *\<^sub>R v) S = y}"
 proof -
   have *: "\<exists>h. sum h S = 1 \<and> (\<Sum>v\<in>S. h v *\<^sub>R v) = x" 
     if "F \<subseteq> S" "finite F" "F \<noteq> {}" and sum: "sum u F = 1" and x: "(\<Sum>v\<in>F. u v *\<^sub>R v) = x" for x F u
   proof -
     have "S \<inter> F = F"
       using that by auto
     show ?thesis
     proof (intro exI conjI)
       show "(\<Sum>x\<in>S. if x \<in> F then u x else 0) = 1"
         by (metis (mono_tags, lifting) \<open>S \<inter> F = F\<close> assms sum.inter_restrict sum)
       show "(\<Sum>v\<in>S. (if v \<in> F then u v else 0) *\<^sub>R v) = x"
         by (simp add: if_smult cong: if_cong) (metis (no_types) \<open>S \<inter> F = F\<close> assms sum.inter_restrict x)
     qed
   qed
   show ?thesis
     unfolding affine_hull_explicit using assms
     by (fastforce dest: *)
 qed
 
 
 subsubsection\<^marker>\<open>tag unimportant\<close> \<open>Stepping theorems and hence small special cases\<close>
 
 lemma affine_hull_empty[simp]: "affine hull {} = {}"
   by simp
 
 lemma affine_hull_finite_step:
   fixes y :: "'a::real_vector"
   shows "finite S \<Longrightarrow>
       (\<exists>u. sum u (insert a S) = w \<and> sum (\<lambda>x. u x *\<^sub>R x) (insert a S) = y) \<longleftrightarrow>
       (\<exists>v u. sum u S = w - v \<and> sum (\<lambda>x. u x *\<^sub>R x) S = y - v *\<^sub>R a)" (is "_ \<Longrightarrow> ?lhs = ?rhs")
 proof -
   assume fin: "finite S"
   show "?lhs = ?rhs"
   proof
     assume ?lhs
     then obtain u where u: "sum u (insert a S) = w \<and> (\<Sum>x\<in>insert a S. u x *\<^sub>R x) = y"
       by auto
     show ?rhs
     proof (cases "a \<in> S")
       case True
       then show ?thesis
         using u by (simp add: insert_absorb) (metis diff_zero real_vector.scale_zero_left)
     next
       case False
       show ?thesis
         by (rule exI [where x="u a"]) (use u fin False in auto)
     qed
   next
     assume ?rhs
     then obtain v u where vu: "sum u S = w - v"  "(\<Sum>x\<in>S. u x *\<^sub>R x) = y - v *\<^sub>R a"
       by auto
     have *: "\<And>x M. (if x = a then v else M) *\<^sub>R x = (if x = a then v *\<^sub>R x else M *\<^sub>R x)"
       by auto
     show ?lhs
     proof (cases "a \<in> S")
       case True
       show ?thesis
         by (rule exI [where x="\<lambda>x. (if x=a then v else 0) + u x"])
            (simp add: True scaleR_left_distrib sum.distrib sum_clauses fin vu * cong: if_cong)
     next
       case False
       then show ?thesis
         apply (rule_tac x="\<lambda>x. if x=a then v else u x" in exI) 
         apply (simp add: vu sum_clauses(2)[OF fin] *)
         by (simp add: sum_delta_notmem(3) vu)
     qed
   qed
 qed
 
 lemma affine_hull_2:
   fixes a b :: "'a::real_vector"
   shows "affine hull {a,b} = {u *\<^sub>R a + v *\<^sub>R b| u v. (u + v = 1)}"
   (is "?lhs = ?rhs")
 proof -
   have *:
     "\<And>x y z. z = x - y \<longleftrightarrow> y + z = (x::real)"
     "\<And>x y z. z = x - y \<longleftrightarrow> y + z = (x::'a)" by auto
   have "?lhs = {y. \<exists>u. sum u {a, b} = 1 \<and> (\<Sum>v\<in>{a, b}. u v *\<^sub>R v) = y}"
     using affine_hull_finite[of "{a,b}"] by auto
   also have "\<dots> = {y. \<exists>v u. u b = 1 - v \<and> u b *\<^sub>R b = y - v *\<^sub>R a}"
     by (simp add: affine_hull_finite_step[of "{b}" a])
   also have "\<dots> = ?rhs" unfolding * by auto
   finally show ?thesis by auto
 qed
 
 lemma affine_hull_3:
   fixes a b c :: "'a::real_vector"
   shows "affine hull {a,b,c} = { u *\<^sub>R a + v *\<^sub>R b + w *\<^sub>R c| u v w. u + v + w = 1}"
 proof -
   have *:
     "\<And>x y z. z = x - y \<longleftrightarrow> y + z = (x::real)"
     "\<And>x y z. z = x - y \<longleftrightarrow> y + z = (x::'a)" by auto
   show ?thesis
     apply (simp add: affine_hull_finite affine_hull_finite_step)
     unfolding *
     apply safe
      apply (metis add.assoc)
     apply (rule_tac x=u in exI, force)
     done
 qed
 
 lemma mem_affine:
   assumes "affine S" "x \<in> S" "y \<in> S" "u + v = 1"
   shows "u *\<^sub>R x + v *\<^sub>R y \<in> S"
   using assms affine_def[of S] by auto
 
 lemma mem_affine_3:
   assumes "affine S" "x \<in> S" "y \<in> S" "z \<in> S" "u + v + w = 1"
   shows "u *\<^sub>R x + v *\<^sub>R y + w *\<^sub>R z \<in> S"
 proof -
   have "u *\<^sub>R x + v *\<^sub>R y + w *\<^sub>R z \<in> affine hull {x, y, z}"
     using affine_hull_3[of x y z] assms by auto
   moreover
   have "affine hull {x, y, z} \<subseteq> affine hull S"
     using hull_mono[of "{x, y, z}" "S"] assms by auto
   moreover
   have "affine hull S = S"
     using assms affine_hull_eq[of S] by auto
   ultimately show ?thesis by auto
 qed
 
 lemma mem_affine_3_minus:
   assumes "affine S" "x \<in> S" "y \<in> S" "z \<in> S"
   shows "x + v *\<^sub>R (y-z) \<in> S"
   using mem_affine_3[of S x y z 1 v "-v"] assms
   by (simp add: algebra_simps)
 
 corollary%unimportant mem_affine_3_minus2:
     "\<lbrakk>affine S; x \<in> S; y \<in> S; z \<in> S\<rbrakk> \<Longrightarrow> x - v *\<^sub>R (y-z) \<in> S"
   by (metis add_uminus_conv_diff mem_affine_3_minus real_vector.scale_minus_left)
 
 
 subsubsection\<^marker>\<open>tag unimportant\<close> \<open>Some relations between affine hull and subspaces\<close>
 
 lemma affine_hull_insert_subset_span:
   "affine hull (insert a S) \<subseteq> {a + v| v . v \<in> span {x - a | x . x \<in> S}}"
 proof -
   have "\<exists>v T u. x = a + v \<and> (finite T \<and> T \<subseteq> {x - a |x. x \<in> S} \<and> (\<Sum>v\<in>T. u v *\<^sub>R v) = v)"
     if "finite F" "F \<noteq> {}" "F \<subseteq> insert a S" "sum u F = 1" "(\<Sum>v\<in>F. u v *\<^sub>R v) = x"
     for x F u
   proof -
     have *: "(\<lambda>x. x - a) ` (F - {a}) \<subseteq> {x - a |x. x \<in> S}"
       using that by auto
     show ?thesis
     proof (intro exI conjI)
       show "finite ((\<lambda>x. x - a) ` (F - {a}))"
         by (simp add: that(1))
       show "(\<Sum>v\<in>(\<lambda>x. x - a) ` (F - {a}). u(v+a) *\<^sub>R v) = x-a"
         by (simp add: sum.reindex[unfolded inj_on_def] algebra_simps
             sum_subtractf scaleR_left.sum[symmetric] sum_diff1 that)
     qed (use \<open>F \<subseteq> insert a S\<close> in auto)
   qed
   then show ?thesis
     unfolding affine_hull_explicit span_explicit by fast
 qed
 
 lemma affine_hull_insert_span:
   assumes "a \<notin> S"
   shows "affine hull (insert a S) = {a + v | v . v \<in> span {x - a | x.  x \<in> S}}"
 proof -
   have *: "\<exists>G u. finite G \<and> G \<noteq> {} \<and> G \<subseteq> insert a S \<and> sum u G = 1 \<and> (\<Sum>v\<in>G. u v *\<^sub>R v) = y"
     if "v \<in> span {x - a |x. x \<in> S}" "y = a + v" for y v
   proof -
     from that
     obtain T u where u: "finite T" "T \<subseteq> {x - a |x. x \<in> S}" "a + (\<Sum>v\<in>T. u v *\<^sub>R v) = y"
       unfolding span_explicit by auto
     define F where "F = (\<lambda>x. x + a) ` T"
     have F: "finite F" "F \<subseteq> S" "(\<Sum>v\<in>F. u (v - a) *\<^sub>R (v - a)) = y - a"
       unfolding F_def using u by (auto simp: sum.reindex[unfolded inj_on_def])
     have *: "F \<inter> {a} = {}" "F \<inter> - {a} = F"
       using F assms by auto
     show "\<exists>G u. finite G \<and> G \<noteq> {} \<and> G \<subseteq> insert a S \<and> sum u G = 1 \<and> (\<Sum>v\<in>G. u v *\<^sub>R v) = y"
       apply (rule_tac x = "insert a F" in exI)
       apply (rule_tac x = "\<lambda>x. if x=a then 1 - sum (\<lambda>x. u (x - a)) F else u (x - a)" in exI)
       using assms F
       apply (auto simp:  sum_clauses sum.If_cases if_smult sum_subtractf scaleR_left.sum algebra_simps *)
       done
   qed
   show ?thesis
     by (intro subset_antisym affine_hull_insert_subset_span) (auto simp: affine_hull_explicit dest!: *)
 qed
 
 lemma affine_hull_span:
   assumes "a \<in> S"
   shows "affine hull S = {a + v | v. v \<in> span {x - a | x. x \<in> S - {a}}}"
   using affine_hull_insert_span[of a "S - {a}", unfolded insert_Diff[OF assms]] by auto
 
 
 subsubsection\<^marker>\<open>tag unimportant\<close> \<open>Parallel affine sets\<close>
 
 definition affine_parallel :: "'a::real_vector set \<Rightarrow> 'a::real_vector set \<Rightarrow> bool"
   where "affine_parallel S T \<longleftrightarrow> (\<exists>a. T = (\<lambda>x. a + x) ` S)"
 
 lemma affine_parallel_expl_aux:
   fixes S T :: "'a::real_vector set"
   assumes "\<And>x. x \<in> S \<longleftrightarrow> a + x \<in> T"
   shows "T = (\<lambda>x. a + x) ` S"
 proof -
   have "x \<in> ((\<lambda>x. a + x) ` S)" if "x \<in> T" for x
     using that
     by (simp add: image_iff) (metis add.commute diff_add_cancel assms)
   moreover have "T \<ge> (\<lambda>x. a + x) ` S"
     using assms by auto
   ultimately show ?thesis by auto
 qed
 
 lemma affine_parallel_expl: "affine_parallel S T \<longleftrightarrow> (\<exists>a. \<forall>x. x \<in> S \<longleftrightarrow> a + x \<in> T)"
   by (auto simp add: affine_parallel_def)
     (use affine_parallel_expl_aux [of S _ T] in blast)
 
 lemma affine_parallel_reflex: "affine_parallel S S"
   unfolding affine_parallel_def
   using image_add_0 by blast
 
 lemma affine_parallel_commut:
   assumes "affine_parallel A B"
   shows "affine_parallel B A"
 proof -
   from assms obtain a where B: "B = (\<lambda>x. a + x) ` A"
     unfolding affine_parallel_def by auto
   have [simp]: "(\<lambda>x. x - a) = plus (- a)" by (simp add: fun_eq_iff)
   from B show ?thesis
     using translation_galois [of B a A]
     unfolding affine_parallel_def by blast
 qed
 
 lemma affine_parallel_assoc:
   assumes "affine_parallel A B"
     and "affine_parallel B C"
   shows "affine_parallel A C"
 proof -
   from assms obtain ab where "B = (\<lambda>x. ab + x) ` A"
     unfolding affine_parallel_def by auto
   moreover
   from assms obtain bc where "C = (\<lambda>x. bc + x) ` B"
     unfolding affine_parallel_def by auto
   ultimately show ?thesis
     using translation_assoc[of bc ab A] unfolding affine_parallel_def by auto
 qed
 
 lemma affine_translation_aux:
   fixes a :: "'a::real_vector"
   assumes "affine ((\<lambda>x. a + x) ` S)"
   shows "affine S"
 proof -
   {
     fix x y u v
     assume xy: "x \<in> S" "y \<in> S" "(u :: real) + v = 1"
     then have "(a + x) \<in> ((\<lambda>x. a + x) ` S)" "(a + y) \<in> ((\<lambda>x. a + x) ` S)"
       by auto
     then have h1: "u *\<^sub>R  (a + x) + v *\<^sub>R (a + y) \<in> (\<lambda>x. a + x) ` S"
       using xy assms unfolding affine_def by auto
     have "u *\<^sub>R (a + x) + v *\<^sub>R (a + y) = (u + v) *\<^sub>R a + (u *\<^sub>R x + v *\<^sub>R y)"
       by (simp add: algebra_simps)
     also have "\<dots> = a + (u *\<^sub>R x + v *\<^sub>R y)"
       using \<open>u + v = 1\<close> by auto
     ultimately have "a + (u *\<^sub>R x + v *\<^sub>R y) \<in> (\<lambda>x. a + x) ` S"
       using h1 by auto
     then have "u *\<^sub>R x + v *\<^sub>R y \<in> S" by auto
   }
   then show ?thesis unfolding affine_def by auto
 qed
 
 lemma affine_translation:
   "affine S \<longleftrightarrow> affine ((+) a ` S)" for a :: "'a::real_vector"
 proof
   show "affine ((+) a ` S)" if "affine S"
     using that translation_assoc [of "- a" a S]
     by (auto intro: affine_translation_aux [of "- a" "((+) a ` S)"])
   show "affine S" if "affine ((+) a ` S)"
     using that by (rule affine_translation_aux)
 qed
 
 lemma parallel_is_affine:
   fixes S T :: "'a::real_vector set"
   assumes "affine S" "affine_parallel S T"
   shows "affine T"
 proof -
   from assms obtain a where "T = (\<lambda>x. a + x) ` S"
     unfolding affine_parallel_def by auto
   then show ?thesis
     using affine_translation assms by auto
 qed
 
 lemma subspace_imp_affine: "subspace s \<Longrightarrow> affine s"
   unfolding subspace_def affine_def by auto
 
 lemma affine_hull_subset_span: "(affine hull s) \<subseteq> (span s)"
   by (metis hull_minimal span_superset subspace_imp_affine subspace_span)
 
 
 subsubsection\<^marker>\<open>tag unimportant\<close> \<open>Subspace parallel to an affine set\<close>
 
 lemma subspace_affine: "subspace S \<longleftrightarrow> affine S \<and> 0 \<in> S"
 proof -
   have h0: "subspace S \<Longrightarrow> affine S \<and> 0 \<in> S"
     using subspace_imp_affine[of S] subspace_0 by auto
   {
     assume assm: "affine S \<and> 0 \<in> S"
     {
       fix c :: real
       fix x
       assume x: "x \<in> S"
       have "c *\<^sub>R x = (1-c) *\<^sub>R 0 + c *\<^sub>R x" by auto
       moreover
       have "(1 - c) *\<^sub>R 0 + c *\<^sub>R x \<in> S"
         using affine_alt[of S] assm x by auto
       ultimately have "c *\<^sub>R x \<in> S" by auto
     }
     then have h1: "\<forall>c. \<forall>x \<in> S. c *\<^sub>R x \<in> S" by auto
 
     {
       fix x y
       assume xy: "x \<in> S" "y \<in> S"
       define u where "u = (1 :: real)/2"
       have "(1/2) *\<^sub>R (x+y) = (1/2) *\<^sub>R (x+y)"
         by auto
       moreover
       have "(1/2) *\<^sub>R (x+y)=(1/2) *\<^sub>R x + (1-(1/2)) *\<^sub>R y"
         by (simp add: algebra_simps)
       moreover
       have "(1 - u) *\<^sub>R x + u *\<^sub>R y \<in> S"
         using affine_alt[of S] assm xy by auto
       ultimately
       have "(1/2) *\<^sub>R (x+y) \<in> S"
         using u_def by auto
       moreover
       have "x + y = 2 *\<^sub>R ((1/2) *\<^sub>R (x+y))"
         by auto
       ultimately
       have "x + y \<in> S"
         using h1[rule_format, of "(1/2) *\<^sub>R (x+y)" "2"] by auto
     }
     then have "\<forall>x \<in> S. \<forall>y \<in> S. x + y \<in> S"
       by auto
     then have "subspace S"
       using h1 assm unfolding subspace_def by auto
   }
   then show ?thesis using h0 by metis
 qed
 
 lemma affine_diffs_subspace:
   assumes "affine S" "a \<in> S"
   shows "subspace ((\<lambda>x. (-a)+x) ` S)"
 proof -
   have [simp]: "(\<lambda>x. x - a) = plus (- a)" by (simp add: fun_eq_iff)
   have "affine ((\<lambda>x. (-a)+x) ` S)"
     using affine_translation assms by blast
   moreover have "0 \<in> ((\<lambda>x. (-a)+x) ` S)"
     using assms exI[of "(\<lambda>x. x\<in>S \<and> -a+x = 0)" a] by auto
   ultimately show ?thesis using subspace_affine by auto
 qed
 
 lemma affine_diffs_subspace_subtract:
   "subspace ((\<lambda>x. x - a) ` S)" if "affine S" "a \<in> S"
   using that affine_diffs_subspace [of _ a] by simp
 
 lemma parallel_subspace_explicit:
   assumes "affine S"
     and "a \<in> S"
   assumes "L \<equiv> {y. \<exists>x \<in> S. (-a) + x = y}"
   shows "subspace L \<and> affine_parallel S L"
 proof -
   from assms have "L = plus (- a) ` S" by auto
   then have par: "affine_parallel S L"
     unfolding affine_parallel_def ..
   then have "affine L" using assms parallel_is_affine by auto
   moreover have "0 \<in> L"
     using assms by auto
   ultimately show ?thesis
     using subspace_affine par by auto
 qed
 
 lemma parallel_subspace_aux:
   assumes "subspace A"
     and "subspace B"
     and "affine_parallel A B"
   shows "A \<supseteq> B"
 proof -
   from assms obtain a where a: "\<forall>x. x \<in> A \<longleftrightarrow> a + x \<in> B"
     using affine_parallel_expl[of A B] by auto
   then have "-a \<in> A"
     using assms subspace_0[of B] by auto
   then have "a \<in> A"
     using assms subspace_neg[of A "-a"] by auto
   then show ?thesis
     using assms a unfolding subspace_def by auto
 qed
 
 lemma parallel_subspace:
   assumes "subspace A"
     and "subspace B"
     and "affine_parallel A B"
   shows "A = B"
 proof
   show "A \<supseteq> B"
     using assms parallel_subspace_aux by auto
   show "A \<subseteq> B"
     using assms parallel_subspace_aux[of B A] affine_parallel_commut by auto
 qed
 
 lemma affine_parallel_subspace:
   assumes "affine S" "S \<noteq> {}"
   shows "\<exists>!L. subspace L \<and> affine_parallel S L"
 proof -
   have ex: "\<exists>L. subspace L \<and> affine_parallel S L"
     using assms parallel_subspace_explicit by auto
   {
     fix L1 L2
     assume ass: "subspace L1 \<and> affine_parallel S L1" "subspace L2 \<and> affine_parallel S L2"
     then have "affine_parallel L1 L2"
       using affine_parallel_commut[of S L1] affine_parallel_assoc[of L1 S L2] by auto
     then have "L1 = L2"
       using ass parallel_subspace by auto
   }
   then show ?thesis using ex by auto
 qed
 
 
 subsection \<open>Affine Dependence\<close>
 
 text "Formalized by Lars Schewe."
 
 definition\<^marker>\<open>tag important\<close> affine_dependent :: "'a::real_vector set \<Rightarrow> bool"
   where "affine_dependent s \<longleftrightarrow> (\<exists>x\<in>s. x \<in> affine hull (s - {x}))"
 
 lemma affine_dependent_imp_dependent: "affine_dependent s \<Longrightarrow> dependent s"
   unfolding affine_dependent_def dependent_def
   using affine_hull_subset_span by auto
 
 lemma affine_dependent_subset:
    "\<lbrakk>affine_dependent s; s \<subseteq> t\<rbrakk> \<Longrightarrow> affine_dependent t"
 apply (simp add: affine_dependent_def Bex_def)
 apply (blast dest: hull_mono [OF Diff_mono [OF _ subset_refl]])
 done
 
 lemma affine_independent_subset:
   shows "\<lbrakk>\<not> affine_dependent t; s \<subseteq> t\<rbrakk> \<Longrightarrow> \<not> affine_dependent s"
 by (metis affine_dependent_subset)
 
 lemma affine_independent_Diff:
    "\<not> affine_dependent s \<Longrightarrow> \<not> affine_dependent(s - t)"
 by (meson Diff_subset affine_dependent_subset)
 
 proposition affine_dependent_explicit:
   "affine_dependent p \<longleftrightarrow>
     (\<exists>S u. finite S \<and> S \<subseteq> p \<and> sum u S = 0 \<and> (\<exists>v\<in>S. u v \<noteq> 0) \<and> sum (\<lambda>v. u v *\<^sub>R v) S = 0)"
 proof -
   have "\<exists>S u. finite S \<and> S \<subseteq> p \<and> sum u S = 0 \<and> (\<exists>v\<in>S. u v \<noteq> 0) \<and> (\<Sum>w\<in>S. u w *\<^sub>R w) = 0"
     if "(\<Sum>w\<in>S. u w *\<^sub>R w) = x" "x \<in> p" "finite S" "S \<noteq> {}" "S \<subseteq> p - {x}" "sum u S = 1" for x S u
   proof (intro exI conjI)
     have "x \<notin> S" 
       using that by auto
     then show "(\<Sum>v \<in> insert x S. if v = x then - 1 else u v) = 0"
       using that by (simp add: sum_delta_notmem)
     show "(\<Sum>w \<in> insert x S. (if w = x then - 1 else u w) *\<^sub>R w) = 0"
       using that \<open>x \<notin> S\<close> by (simp add: if_smult sum_delta_notmem cong: if_cong)
   qed (use that in auto)
   moreover have "\<exists>x\<in>p. \<exists>S u. finite S \<and> S \<noteq> {} \<and> S \<subseteq> p - {x} \<and> sum u S = 1 \<and> (\<Sum>v\<in>S. u v *\<^sub>R v) = x"
     if "(\<Sum>v\<in>S. u v *\<^sub>R v) = 0" "finite S" "S \<subseteq> p" "sum u S = 0" "v \<in> S" "u v \<noteq> 0" for S u v
   proof (intro bexI exI conjI)
     have "S \<noteq> {v}"
       using that by auto
     then show "S - {v} \<noteq> {}"
       using that by auto
     show "(\<Sum>x \<in> S - {v}. - (1 / u v) * u x) = 1"
       unfolding sum_distrib_left[symmetric] sum_diff1[OF \<open>finite S\<close>] by (simp add: that)
     show "(\<Sum>x\<in>S - {v}. (- (1 / u v) * u x) *\<^sub>R x) = v"
       unfolding sum_distrib_left [symmetric] scaleR_scaleR[symmetric]
                 scaleR_right.sum [symmetric] sum_diff1[OF \<open>finite S\<close>] 
       using that by auto
     show "S - {v} \<subseteq> p - {v}"
       using that by auto
   qed (use that in auto)
   ultimately show ?thesis
     unfolding affine_dependent_def affine_hull_explicit by auto
 qed
 
 lemma affine_dependent_explicit_finite:
   fixes S :: "'a::real_vector set"
   assumes "finite S"
   shows "affine_dependent S \<longleftrightarrow>
     (\<exists>u. sum u S = 0 \<and> (\<exists>v\<in>S. u v \<noteq> 0) \<and> sum (\<lambda>v. u v *\<^sub>R v) S = 0)"
   (is "?lhs = ?rhs")
 proof
   have *: "\<And>vt u v. (if vt then u v else 0) *\<^sub>R v = (if vt then (u v) *\<^sub>R v else 0::'a)"
     by auto
   assume ?lhs
   then obtain t u v where
     "finite t" "t \<subseteq> S" "sum u t = 0" "v\<in>t" "u v \<noteq> 0"  "(\<Sum>v\<in>t. u v *\<^sub>R v) = 0"
     unfolding affine_dependent_explicit by auto
   then show ?rhs
     apply (rule_tac x="\<lambda>x. if x\<in>t then u x else 0" in exI)
     apply (auto simp: * sum.inter_restrict[OF assms, symmetric] Int_absorb1[OF \<open>t\<subseteq>S\<close>])
     done
 next
   assume ?rhs
   then obtain u v where "sum u S = 0"  "v\<in>S" "u v \<noteq> 0" "(\<Sum>v\<in>S. u v *\<^sub>R v) = 0"
     by auto
   then show ?lhs unfolding affine_dependent_explicit
     using assms by auto
 qed
 
 lemma dependent_imp_affine_dependent:
   assumes "dependent {x - a| x . x \<in> s}"
     and "a \<notin> s"
   shows "affine_dependent (insert a s)"
 proof -
   from assms(1)[unfolded dependent_explicit] obtain S u v
     where obt: "finite S" "S \<subseteq> {x - a |x. x \<in> s}" "v\<in>S" "u v  \<noteq> 0" "(\<Sum>v\<in>S. u v *\<^sub>R v) = 0"
     by auto
   define t where "t = (\<lambda>x. x + a) ` S"
 
   have inj: "inj_on (\<lambda>x. x + a) S"
     unfolding inj_on_def by auto
   have "0 \<notin> S"
     using obt(2) assms(2) unfolding subset_eq by auto
   have fin: "finite t" and "t \<subseteq> s"
     unfolding t_def using obt(1,2) by auto
   then have "finite (insert a t)" and "insert a t \<subseteq> insert a s"
     by auto
   moreover have *: "\<And>P Q. (\<Sum>x\<in>t. (if x = a then P x else Q x)) = (\<Sum>x\<in>t. Q x)"
     apply (rule sum.cong)
     using \<open>a\<notin>s\<close> \<open>t\<subseteq>s\<close>
     apply auto
     done
   have "(\<Sum>x\<in>insert a t. if x = a then - (\<Sum>x\<in>t. u (x - a)) else u (x - a)) = 0"
     unfolding sum_clauses(2)[OF fin] * using \<open>a\<notin>s\<close> \<open>t\<subseteq>s\<close> by auto
   moreover have "\<exists>v\<in>insert a t. (if v = a then - (\<Sum>x\<in>t. u (x - a)) else u (v - a)) \<noteq> 0"
     using obt(3,4) \<open>0\<notin>S\<close>
     by (rule_tac x="v + a" in bexI) (auto simp: t_def)
   moreover have *: "\<And>P Q. (\<Sum>x\<in>t. (if x = a then P x else Q x) *\<^sub>R x) = (\<Sum>x\<in>t. Q x *\<^sub>R x)"
     using \<open>a\<notin>s\<close> \<open>t\<subseteq>s\<close> by (auto intro!: sum.cong)
   have "(\<Sum>x\<in>t. u (x - a)) *\<^sub>R a = (\<Sum>v\<in>t. u (v - a) *\<^sub>R v)"
     unfolding scaleR_left.sum
     unfolding t_def and sum.reindex[OF inj] and o_def
     using obt(5)
     by (auto simp: sum.distrib scaleR_right_distrib)
   then have "(\<Sum>v\<in>insert a t. (if v = a then - (\<Sum>x\<in>t. u (x - a)) else u (v - a)) *\<^sub>R v) = 0"
     unfolding sum_clauses(2)[OF fin]
     using \<open>a\<notin>s\<close> \<open>t\<subseteq>s\<close>
     by (auto simp: *)
   ultimately show ?thesis
     unfolding affine_dependent_explicit
     apply (rule_tac x="insert a t" in exI, auto)
     done
 qed
 
 lemma affine_dependent_biggerset:
   fixes s :: "'a::euclidean_space set"
   assumes "finite s" "card s \<ge> DIM('a) + 2"
   shows "affine_dependent s"
 proof -
   have "s \<noteq> {}" using assms by auto
   then obtain a where "a\<in>s" by auto
   have *: "{x - a |x. x \<in> s - {a}} = (\<lambda>x. x - a) ` (s - {a})"
     by auto
   have "card {x - a |x. x \<in> s - {a}} = card (s - {a})"
     unfolding * by (simp add: card_image inj_on_def)
   also have "\<dots> > DIM('a)" using assms(2)
     unfolding card_Diff_singleton[OF assms(1) \<open>a\<in>s\<close>] by auto
   finally show ?thesis
     apply (subst insert_Diff[OF \<open>a\<in>s\<close>, symmetric])
     apply (rule dependent_imp_affine_dependent)
     apply (rule dependent_biggerset, auto)
     done
 qed
 
 lemma affine_dependent_biggerset_general:
   assumes "finite (S :: 'a::euclidean_space set)"
     and "card S \<ge> dim S + 2"
   shows "affine_dependent S"
 proof -
   from assms(2) have "S \<noteq> {}" by auto
   then obtain a where "a\<in>S" by auto
   have *: "{x - a |x. x \<in> S - {a}} = (\<lambda>x. x - a) ` (S - {a})"
     by auto
   have **: "card {x - a |x. x \<in> S - {a}} = card (S - {a})"
     by (metis (no_types, lifting) "*" card_image diff_add_cancel inj_on_def)
   have "dim {x - a |x. x \<in> S - {a}} \<le> dim S"
     using \<open>a\<in>S\<close> by (auto simp: span_base span_diff intro: subset_le_dim)
   also have "\<dots> < dim S + 1" by auto
   also have "\<dots> \<le> card (S - {a})"
     using assms
     using card_Diff_singleton[OF assms(1) \<open>a\<in>S\<close>]
     by auto
   finally show ?thesis
     apply (subst insert_Diff[OF \<open>a\<in>S\<close>, symmetric])
     apply (rule dependent_imp_affine_dependent)
     apply (rule dependent_biggerset_general)
     unfolding **
     apply auto
     done
 qed
 
 
 subsection\<^marker>\<open>tag unimportant\<close> \<open>Some Properties of Affine Dependent Sets\<close>
 
 lemma affine_independent_0 [simp]: "\<not> affine_dependent {}"
   by (simp add: affine_dependent_def)
 
 lemma affine_independent_1 [simp]: "\<not> affine_dependent {a}"
   by (simp add: affine_dependent_def)
 
 lemma affine_independent_2 [simp]: "\<not> affine_dependent {a,b}"
   by (simp add: affine_dependent_def insert_Diff_if hull_same)
 
 lemma affine_hull_translation: "affine hull ((\<lambda>x. a + x) `  S) = (\<lambda>x. a + x) ` (affine hull S)"
 proof -
   have "affine ((\<lambda>x. a + x) ` (affine hull S))"
     using affine_translation affine_affine_hull by blast
   moreover have "(\<lambda>x. a + x) `  S \<subseteq> (\<lambda>x. a + x) ` (affine hull S)"
     using hull_subset[of S] by auto
   ultimately have h1: "affine hull ((\<lambda>x. a + x) `  S) \<subseteq> (\<lambda>x. a + x) ` (affine hull S)"
     by (metis hull_minimal)
   have "affine((\<lambda>x. -a + x) ` (affine hull ((\<lambda>x. a + x) `  S)))"
     using affine_translation affine_affine_hull by blast
   moreover have "(\<lambda>x. -a + x) ` (\<lambda>x. a + x) `  S \<subseteq> (\<lambda>x. -a + x) ` (affine hull ((\<lambda>x. a + x) `  S))"
     using hull_subset[of "(\<lambda>x. a + x) `  S"] by auto
   moreover have "S = (\<lambda>x. -a + x) ` (\<lambda>x. a + x) `  S"
     using translation_assoc[of "-a" a] by auto
   ultimately have "(\<lambda>x. -a + x) ` (affine hull ((\<lambda>x. a + x) `  S)) >= (affine hull S)"
     by (metis hull_minimal)
   then have "affine hull ((\<lambda>x. a + x) ` S) >= (\<lambda>x. a + x) ` (affine hull S)"
     by auto
   then show ?thesis using h1 by auto
 qed
 
 lemma affine_dependent_translation:
   assumes "affine_dependent S"
   shows "affine_dependent ((\<lambda>x. a + x) ` S)"
 proof -
   obtain x where x: "x \<in> S \<and> x \<in> affine hull (S - {x})"
     using assms affine_dependent_def by auto
   have "(+) a ` (S - {x}) = (+) a ` S - {a + x}"
     by auto
   then have "a + x \<in> affine hull ((\<lambda>x. a + x) ` S - {a + x})"
     using affine_hull_translation[of a "S - {x}"] x by auto
   moreover have "a + x \<in> (\<lambda>x. a + x) ` S"
     using x by auto
   ultimately show ?thesis
     unfolding affine_dependent_def by auto
 qed
 
 lemma affine_dependent_translation_eq:
   "affine_dependent S \<longleftrightarrow> affine_dependent ((\<lambda>x. a + x) ` S)"
 proof -
   {
     assume "affine_dependent ((\<lambda>x. a + x) ` S)"
     then have "affine_dependent S"
       using affine_dependent_translation[of "((\<lambda>x. a + x) ` S)" "-a"] translation_assoc[of "-a" a]
       by auto
   }
   then show ?thesis
     using affine_dependent_translation by auto
 qed
 
 lemma affine_hull_0_dependent:
   assumes "0 \<in> affine hull S"
   shows "dependent S"
 proof -
   obtain s u where s_u: "finite s \<and> s \<noteq> {} \<and> s \<subseteq> S \<and> sum u s = 1 \<and> (\<Sum>v\<in>s. u v *\<^sub>R v) = 0"
     using assms affine_hull_explicit[of S] by auto
   then have "\<exists>v\<in>s. u v \<noteq> 0" by auto
   then have "finite s \<and> s \<subseteq> S \<and> (\<exists>v\<in>s. u v \<noteq> 0 \<and> (\<Sum>v\<in>s. u v *\<^sub>R v) = 0)"
     using s_u by auto
   then show ?thesis
     unfolding dependent_explicit[of S] by auto
 qed
 
 lemma affine_dependent_imp_dependent2:
   assumes "affine_dependent (insert 0 S)"
   shows "dependent S"
 proof -
   obtain x where x: "x \<in> insert 0 S \<and> x \<in> affine hull (insert 0 S - {x})"
     using affine_dependent_def[of "(insert 0 S)"] assms by blast
   then have "x \<in> span (insert 0 S - {x})"
     using affine_hull_subset_span by auto
   moreover have "span (insert 0 S - {x}) = span (S - {x})"
     using insert_Diff_if[of "0" S "{x}"] span_insert_0[of "S-{x}"] by auto
   ultimately have "x \<in> span (S - {x})" by auto
   then have "x \<noteq> 0 \<Longrightarrow> dependent S"
     using x dependent_def by auto
   moreover
   {
     assume "x = 0"
     then have "0 \<in> affine hull S"
       using x hull_mono[of "S - {0}" S] by auto
     then have "dependent S"
       using affine_hull_0_dependent by auto
   }
   ultimately show ?thesis by auto
 qed
 
 lemma affine_dependent_iff_dependent:
   assumes "a \<notin> S"
   shows "affine_dependent (insert a S) \<longleftrightarrow> dependent ((\<lambda>x. -a + x) ` S)"
 proof -
   have "((+) (- a) ` S) = {x - a| x . x \<in> S}" by auto
   then show ?thesis
     using affine_dependent_translation_eq[of "(insert a S)" "-a"]
       affine_dependent_imp_dependent2 assms
       dependent_imp_affine_dependent[of a S]
     by (auto simp del: uminus_add_conv_diff)
 qed
 
 lemma affine_dependent_iff_dependent2:
   assumes "a \<in> S"
   shows "affine_dependent S \<longleftrightarrow> dependent ((\<lambda>x. -a + x) ` (S-{a}))"
 proof -
   have "insert a (S - {a}) = S"
     using assms by auto
   then show ?thesis
     using assms affine_dependent_iff_dependent[of a "S-{a}"] by auto
 qed
 
 lemma affine_hull_insert_span_gen:
   "affine hull (insert a s) = (\<lambda>x. a + x) ` span ((\<lambda>x. - a + x) ` s)"
 proof -
   have h1: "{x - a |x. x \<in> s} = ((\<lambda>x. -a+x) ` s)"
     by auto
   {
     assume "a \<notin> s"
     then have ?thesis
       using affine_hull_insert_span[of a s] h1 by auto
   }
   moreover
   {
     assume a1: "a \<in> s"
     have "\<exists>x. x \<in> s \<and> -a+x=0"
       apply (rule exI[of _ a])
       using a1
       apply auto
       done
     then have "insert 0 ((\<lambda>x. -a+x) ` (s - {a})) = (\<lambda>x. -a+x) ` s"
       by auto
     then have "span ((\<lambda>x. -a+x) ` (s - {a}))=span ((\<lambda>x. -a+x) ` s)"
       using span_insert_0[of "(+) (- a) ` (s - {a})"] by (auto simp del: uminus_add_conv_diff)
     moreover have "{x - a |x. x \<in> (s - {a})} = ((\<lambda>x. -a+x) ` (s - {a}))"
       by auto
     moreover have "insert a (s - {a}) = insert a s"
       by auto
     ultimately have ?thesis
       using affine_hull_insert_span[of "a" "s-{a}"] by auto
   }
   ultimately show ?thesis by auto
 qed
 
 lemma affine_hull_span2:
   assumes "a \<in> s"
   shows "affine hull s = (\<lambda>x. a+x) ` span ((\<lambda>x. -a+x) ` (s-{a}))"
   using affine_hull_insert_span_gen[of a "s - {a}", unfolded insert_Diff[OF assms]]
   by auto
 
 lemma affine_hull_span_gen:
   assumes "a \<in> affine hull s"
   shows "affine hull s = (\<lambda>x. a+x) ` span ((\<lambda>x. -a+x) ` s)"
 proof -
   have "affine hull (insert a s) = affine hull s"
     using hull_redundant[of a affine s] assms by auto
   then show ?thesis
     using affine_hull_insert_span_gen[of a "s"] by auto
 qed
 
 lemma affine_hull_span_0:
   assumes "0 \<in> affine hull S"
   shows "affine hull S = span S"
   using affine_hull_span_gen[of "0" S] assms by auto
 
 lemma extend_to_affine_basis_nonempty:
-  fixes S V :: "'n::euclidean_space set"
+  fixes S V :: "'n::real_vector set"
   assumes "\<not> affine_dependent S" "S \<subseteq> V" "S \<noteq> {}"
   shows "\<exists>T. \<not> affine_dependent T \<and> S \<subseteq> T \<and> T \<subseteq> V \<and> affine hull T = affine hull V"
 proof -
   obtain a where a: "a \<in> S"
     using assms by auto
   then have h0: "independent  ((\<lambda>x. -a + x) ` (S-{a}))"
     using affine_dependent_iff_dependent2 assms by auto
   obtain B where B:
     "(\<lambda>x. -a+x) ` (S - {a}) \<subseteq> B \<and> B \<subseteq> (\<lambda>x. -a+x) ` V \<and> independent B \<and> (\<lambda>x. -a+x) ` V \<subseteq> span B"
     using assms
     by (blast intro: maximal_independent_subset_extend[OF _ h0, of "(\<lambda>x. -a + x) ` V"])
   define T where "T = (\<lambda>x. a+x) ` insert 0 B"
   then have "T = insert a ((\<lambda>x. a+x) ` B)"
     by auto
   then have "affine hull T = (\<lambda>x. a+x) ` span B"
     using affine_hull_insert_span_gen[of a "((\<lambda>x. a+x) ` B)"] translation_assoc[of "-a" a B]
     by auto
   then have "V \<subseteq> affine hull T"
     using B assms translation_inverse_subset[of a V "span B"]
     by auto
   moreover have "T \<subseteq> V"
     using T_def B a assms by auto
   ultimately have "affine hull T = affine hull V"
     by (metis Int_absorb1 Int_absorb2 hull_hull hull_mono)
   moreover have "S \<subseteq> T"
     using T_def B translation_inverse_subset[of a "S-{a}" B]
     by auto
   moreover have "\<not> affine_dependent T"
     using T_def affine_dependent_translation_eq[of "insert 0 B"]
       affine_dependent_imp_dependent2 B
     by auto
   ultimately show ?thesis using \<open>T \<subseteq> V\<close> by auto
 qed
 
 lemma affine_basis_exists:
-  fixes V :: "'n::euclidean_space set"
+  fixes V :: "'n::real_vector set"
   shows "\<exists>B. B \<subseteq> V \<and> \<not> affine_dependent B \<and> affine hull V = affine hull B"
 proof (cases "V = {}")
   case True
   then show ?thesis
     using affine_independent_0 by auto
 next
   case False
   then obtain x where "x \<in> V" by auto
   then show ?thesis
     using affine_dependent_def[of "{x}"] extend_to_affine_basis_nonempty[of "{x}" V]
     by auto
 qed
 
 proposition extend_to_affine_basis:
-  fixes S V :: "'n::euclidean_space set"
+  fixes S V :: "'n::real_vector set"
   assumes "\<not> affine_dependent S" "S \<subseteq> V"
   obtains T where "\<not> affine_dependent T" "S \<subseteq> T" "T \<subseteq> V" "affine hull T = affine hull V"
 proof (cases "S = {}")
   case True then show ?thesis
     using affine_basis_exists by (metis empty_subsetI that)
 next
   case False
   then show ?thesis by (metis assms extend_to_affine_basis_nonempty that)
 qed
 
 
 subsection \<open>Affine Dimension of a Set\<close>
 
 definition\<^marker>\<open>tag important\<close> aff_dim :: "('a::euclidean_space) set \<Rightarrow> int"
   where "aff_dim V =
   (SOME d :: int.
     \<exists>B. affine hull B = affine hull V \<and> \<not> affine_dependent B \<and> of_nat (card B) = d + 1)"
 
 lemma aff_dim_basis_exists:
   fixes V :: "('n::euclidean_space) set"
   shows "\<exists>B. affine hull B = affine hull V \<and> \<not> affine_dependent B \<and> of_nat (card B) = aff_dim V + 1"
 proof -
   obtain B where "\<not> affine_dependent B \<and> affine hull B = affine hull V"
     using affine_basis_exists[of V] by auto
   then show ?thesis
     unfolding aff_dim_def
       some_eq_ex[of "\<lambda>d. \<exists>B. affine hull B = affine hull V \<and> \<not> affine_dependent B \<and> of_nat (card B) = d + 1"]
     apply auto
     apply (rule exI[of _ "int (card B) - (1 :: int)"])
     apply (rule exI[of _ "B"], auto)
     done
 qed
 
 lemma affine_hull_eq_empty [simp]: "affine hull S = {} \<longleftrightarrow> S = {}"
 by (metis affine_empty subset_empty subset_hull)
 
 lemma empty_eq_affine_hull[simp]: "{} = affine hull S \<longleftrightarrow> S = {}"
 by (metis affine_hull_eq_empty)
 
 lemma aff_dim_parallel_subspace_aux:
   fixes B :: "'n::euclidean_space set"
   assumes "\<not> affine_dependent B" "a \<in> B"
   shows "finite B \<and> ((card B) - 1 = dim (span ((\<lambda>x. -a+x) ` (B-{a}))))"
 proof -
   have "independent ((\<lambda>x. -a + x) ` (B-{a}))"
     using affine_dependent_iff_dependent2 assms by auto
   then have fin: "dim (span ((\<lambda>x. -a+x) ` (B-{a}))) = card ((\<lambda>x. -a + x) ` (B-{a}))"
     "finite ((\<lambda>x. -a + x) ` (B - {a}))"
     using indep_card_eq_dim_span[of "(\<lambda>x. -a+x) ` (B-{a})"] by auto
   show ?thesis
   proof (cases "(\<lambda>x. -a + x) ` (B - {a}) = {}")
     case True
     have "B = insert a ((\<lambda>x. a + x) ` (\<lambda>x. -a + x) ` (B - {a}))"
       using translation_assoc[of "a" "-a" "(B - {a})"] assms by auto
     then have "B = {a}" using True by auto
     then show ?thesis using assms fin by auto
   next
     case False
     then have "card ((\<lambda>x. -a + x) ` (B - {a})) > 0"
       using fin by auto
     moreover have h1: "card ((\<lambda>x. -a + x) ` (B-{a})) = card (B-{a})"
       by (rule card_image) (use translate_inj_on in blast)
     ultimately have "card (B-{a}) > 0" by auto
     then have *: "finite (B - {a})"
       using card_gt_0_iff[of "(B - {a})"] by auto
     then have "card (B - {a}) = card B - 1"
       using card_Diff_singleton assms by auto
     with * show ?thesis using fin h1 by auto
   qed
 qed
 
 lemma aff_dim_parallel_subspace:
   fixes V L :: "'n::euclidean_space set"
   assumes "V \<noteq> {}"
     and "subspace L"
     and "affine_parallel (affine hull V) L"
   shows "aff_dim V = int (dim L)"
 proof -
   obtain B where
     B: "affine hull B = affine hull V \<and> \<not> affine_dependent B \<and> int (card B) = aff_dim V + 1"
     using aff_dim_basis_exists by auto
   then have "B \<noteq> {}"
     using assms B
     by auto
   then obtain a where a: "a \<in> B" by auto
   define Lb where "Lb = span ((\<lambda>x. -a+x) ` (B-{a}))"
   moreover have "affine_parallel (affine hull B) Lb"
     using Lb_def B assms affine_hull_span2[of a B] a
       affine_parallel_commut[of "Lb" "(affine hull B)"]
     unfolding affine_parallel_def
     by auto
   moreover have "subspace Lb"
     using Lb_def subspace_span by auto
   moreover have "affine hull B \<noteq> {}"
     using assms B by auto
   ultimately have "L = Lb"
     using assms affine_parallel_subspace[of "affine hull B"] affine_affine_hull[of B] B
     by auto
   then have "dim L = dim Lb"
     by auto
   moreover have "card B - 1 = dim Lb" and "finite B"
     using Lb_def aff_dim_parallel_subspace_aux a B by auto
   ultimately show ?thesis
     using B \<open>B \<noteq> {}\<close> card_gt_0_iff[of B] by auto
 qed
 
 lemma aff_independent_finite:
   fixes B :: "'n::euclidean_space set"
   assumes "\<not> affine_dependent B"
   shows "finite B"
 proof -
   {
     assume "B \<noteq> {}"
     then obtain a where "a \<in> B" by auto
     then have ?thesis
       using aff_dim_parallel_subspace_aux assms by auto
   }
   then show ?thesis by auto
 qed
 
 
 lemma aff_dim_empty:
   fixes S :: "'n::euclidean_space set"
   shows "S = {} \<longleftrightarrow> aff_dim S = -1"
 proof -
   obtain B where *: "affine hull B = affine hull S"
     and "\<not> affine_dependent B"
     and "int (card B) = aff_dim S + 1"
     using aff_dim_basis_exists by auto
   moreover
   from * have "S = {} \<longleftrightarrow> B = {}"
     by auto
   ultimately show ?thesis
     using aff_independent_finite[of B] card_gt_0_iff[of B] by auto
 qed
 
 lemma aff_dim_empty_eq [simp]: "aff_dim ({}::'a::euclidean_space set) = -1"
   by (simp add: aff_dim_empty [symmetric])
 
 lemma aff_dim_affine_hull [simp]: "aff_dim (affine hull S) = aff_dim S"
   unfolding aff_dim_def using hull_hull[of _ S] by auto
 
 lemma aff_dim_affine_hull2:
   assumes "affine hull S = affine hull T"
   shows "aff_dim S = aff_dim T"
   unfolding aff_dim_def using assms by auto
 
 lemma aff_dim_unique:
   fixes B V :: "'n::euclidean_space set"
   assumes "affine hull B = affine hull V \<and> \<not> affine_dependent B"
   shows "of_nat (card B) = aff_dim V + 1"
 proof (cases "B = {}")
   case True
   then have "V = {}"
     using assms
     by auto
   then have "aff_dim V = (-1::int)"
     using aff_dim_empty by auto
   then show ?thesis
     using \<open>B = {}\<close> by auto
 next
   case False
   then obtain a where a: "a \<in> B" by auto
   define Lb where "Lb = span ((\<lambda>x. -a+x) ` (B-{a}))"
   have "affine_parallel (affine hull B) Lb"
     using Lb_def affine_hull_span2[of a B] a
       affine_parallel_commut[of "Lb" "(affine hull B)"]
     unfolding affine_parallel_def by auto
   moreover have "subspace Lb"
     using Lb_def subspace_span by auto
   ultimately have "aff_dim B = int(dim Lb)"
     using aff_dim_parallel_subspace[of B Lb] \<open>B \<noteq> {}\<close> by auto
   moreover have "(card B) - 1 = dim Lb" "finite B"
     using Lb_def aff_dim_parallel_subspace_aux a assms by auto
   ultimately have "of_nat (card B) = aff_dim B + 1"
     using \<open>B \<noteq> {}\<close> card_gt_0_iff[of B] by auto
   then show ?thesis
     using aff_dim_affine_hull2 assms by auto
 qed
 
 lemma aff_dim_affine_independent:
   fixes B :: "'n::euclidean_space set"
   assumes "\<not> affine_dependent B"
   shows "of_nat (card B) = aff_dim B + 1"
   using aff_dim_unique[of B B] assms by auto
 
 lemma affine_independent_iff_card:
     fixes s :: "'a::euclidean_space set"
     shows "\<not> affine_dependent s \<longleftrightarrow> finite s \<and> aff_dim s = int(card s) - 1"
   apply (rule iffI)
   apply (simp add: aff_dim_affine_independent aff_independent_finite)
   by (metis affine_basis_exists [of s] aff_dim_unique card_subset_eq diff_add_cancel of_nat_eq_iff)
 
 lemma aff_dim_sing [simp]:
   fixes a :: "'n::euclidean_space"
   shows "aff_dim {a} = 0"
   using aff_dim_affine_independent[of "{a}"] affine_independent_1 by auto
 
-lemma aff_dim_2 [simp]: "aff_dim {a,b} = (if a = b then 0 else 1)"
+lemma aff_dim_2 [simp]:
+  fixes a :: "'n::euclidean_space"
+  shows "aff_dim {a,b} = (if a = b then 0 else 1)"
 proof (clarsimp)
   assume "a \<noteq> b"
   then have "aff_dim{a,b} = card{a,b} - 1"
     using affine_independent_2 [of a b] aff_dim_affine_independent by fastforce
   also have "\<dots> = 1"
     using \<open>a \<noteq> b\<close> by simp
   finally show "aff_dim {a, b} = 1" .
 qed
 
 lemma aff_dim_inner_basis_exists:
   fixes V :: "('n::euclidean_space) set"
   shows "\<exists>B. B \<subseteq> V \<and> affine hull B = affine hull V \<and>
     \<not> affine_dependent B \<and> of_nat (card B) = aff_dim V + 1"
 proof -
   obtain B where B: "\<not> affine_dependent B" "B \<subseteq> V" "affine hull B = affine hull V"
     using affine_basis_exists[of V] by auto
   then have "of_nat(card B) = aff_dim V+1" using aff_dim_unique by auto
   with B show ?thesis by auto
 qed
 
 lemma aff_dim_le_card:
   fixes V :: "'n::euclidean_space set"
   assumes "finite V"
   shows "aff_dim V \<le> of_nat (card V) - 1"
 proof -
   obtain B where B: "B \<subseteq> V" "of_nat (card B) = aff_dim V + 1"
     using aff_dim_inner_basis_exists[of V] by auto
   then have "card B \<le> card V"
     using assms card_mono by auto
   with B show ?thesis by auto
 qed
 
 lemma aff_dim_parallel_eq:
   fixes S T :: "'n::euclidean_space set"
   assumes "affine_parallel (affine hull S) (affine hull T)"
   shows "aff_dim S = aff_dim T"
 proof -
   {
     assume "T \<noteq> {}" "S \<noteq> {}"
     then obtain L where L: "subspace L \<and> affine_parallel (affine hull T) L"
       using affine_parallel_subspace[of "affine hull T"]
         affine_affine_hull[of T]
       by auto
     then have "aff_dim T = int (dim L)"
       using aff_dim_parallel_subspace \<open>T \<noteq> {}\<close> by auto
     moreover have *: "subspace L \<and> affine_parallel (affine hull S) L"
        using L affine_parallel_assoc[of "affine hull S" "affine hull T" L] assms by auto
     moreover from * have "aff_dim S = int (dim L)"
       using aff_dim_parallel_subspace \<open>S \<noteq> {}\<close> by auto
     ultimately have ?thesis by auto
   }
   moreover
   {
     assume "S = {}"
     then have "S = {}" and "T = {}"
       using assms
       unfolding affine_parallel_def
       by auto
     then have ?thesis using aff_dim_empty by auto
   }
   moreover
   {
     assume "T = {}"
     then have "S = {}" and "T = {}"
       using assms
       unfolding affine_parallel_def
       by auto
     then have ?thesis
       using aff_dim_empty by auto
   }
   ultimately show ?thesis by blast
 qed
 
 lemma aff_dim_translation_eq:
   "aff_dim ((+) a ` S) = aff_dim S" for a :: "'n::euclidean_space"
 proof -
   have "affine_parallel (affine hull S) (affine hull ((\<lambda>x. a + x) ` S))"
     unfolding affine_parallel_def
     apply (rule exI[of _ "a"])
     using affine_hull_translation[of a S]
     apply auto
     done
   then show ?thesis
     using aff_dim_parallel_eq[of S "(\<lambda>x. a + x) ` S"] by auto
 qed
 
 lemma aff_dim_translation_eq_subtract:
   "aff_dim ((\<lambda>x. x - a) ` S) = aff_dim S" for a :: "'n::euclidean_space"
   using aff_dim_translation_eq [of "- a"] by (simp cong: image_cong_simp)
 
 lemma aff_dim_affine:
   fixes S L :: "'n::euclidean_space set"
   assumes "S \<noteq> {}"
     and "affine S"
     and "subspace L"
     and "affine_parallel S L"
   shows "aff_dim S = int (dim L)"
 proof -
   have *: "affine hull S = S"
     using assms affine_hull_eq[of S] by auto
   then have "affine_parallel (affine hull S) L"
     using assms by (simp add: *)
   then show ?thesis
     using assms aff_dim_parallel_subspace[of S L] by blast
 qed
 
 lemma dim_affine_hull:
   fixes S :: "'n::euclidean_space set"
   shows "dim (affine hull S) = dim S"
 proof -
   have "dim (affine hull S) \<ge> dim S"
     using dim_subset by auto
   moreover have "dim (span S) \<ge> dim (affine hull S)"
     using dim_subset affine_hull_subset_span by blast
   moreover have "dim (span S) = dim S"
     using dim_span by auto
   ultimately show ?thesis by auto
 qed
 
 lemma aff_dim_subspace:
   fixes S :: "'n::euclidean_space set"
   assumes "subspace S"
   shows "aff_dim S = int (dim S)"
 proof (cases "S={}")
   case True with assms show ?thesis
     by (simp add: subspace_affine)
 next
   case False
   with aff_dim_affine[of S S] assms subspace_imp_affine[of S] affine_parallel_reflex[of S] subspace_affine
   show ?thesis by auto
 qed
 
 lemma aff_dim_zero:
   fixes S :: "'n::euclidean_space set"
   assumes "0 \<in> affine hull S"
   shows "aff_dim S = int (dim S)"
 proof -
   have "subspace (affine hull S)"
     using subspace_affine[of "affine hull S"] affine_affine_hull assms
     by auto
   then have "aff_dim (affine hull S) = int (dim (affine hull S))"
     using assms aff_dim_subspace[of "affine hull S"] by auto
   then show ?thesis
     using aff_dim_affine_hull[of S] dim_affine_hull[of S]
     by auto
 qed
 
 lemma aff_dim_eq_dim:
   "aff_dim S = int (dim ((+) (- a) ` S))" if "a \<in> affine hull S"
     for S :: "'n::euclidean_space set"
 proof -
   have "0 \<in> affine hull (+) (- a) ` S"
     unfolding affine_hull_translation
     using that by (simp add: ac_simps)
   with aff_dim_zero show ?thesis
     by (metis aff_dim_translation_eq)
 qed
 
 lemma aff_dim_eq_dim_subtract:
   "aff_dim S = int (dim ((\<lambda>x. x - a) ` S))" if "a \<in> affine hull S"
     for S :: "'n::euclidean_space set"
   using aff_dim_eq_dim [of a] that by (simp cong: image_cong_simp)
 
 lemma aff_dim_UNIV [simp]: "aff_dim (UNIV :: 'n::euclidean_space set) = int(DIM('n))"
   using aff_dim_subspace[of "(UNIV :: 'n::euclidean_space set)"]
     dim_UNIV[where 'a="'n::euclidean_space"]
   by auto
 
 lemma aff_dim_geq:
   fixes V :: "'n::euclidean_space set"
   shows "aff_dim V \<ge> -1"
 proof -
   obtain B where "affine hull B = affine hull V"
     and "\<not> affine_dependent B"
     and "int (card B) = aff_dim V + 1"
     using aff_dim_basis_exists by auto
   then show ?thesis by auto
 qed
 
 lemma aff_dim_negative_iff [simp]:
   fixes S :: "'n::euclidean_space set"
   shows "aff_dim S < 0 \<longleftrightarrow>S = {}"
 by (metis aff_dim_empty aff_dim_geq diff_0 eq_iff zle_diff1_eq)
 
 lemma aff_lowdim_subset_hyperplane:
   fixes S :: "'a::euclidean_space set"
   assumes "aff_dim S < DIM('a)"
   obtains a b where "a \<noteq> 0" "S \<subseteq> {x. a \<bullet> x = b}"
 proof (cases "S={}")
   case True
   moreover
   have "(SOME b. b \<in> Basis) \<noteq> 0"
     by (metis norm_some_Basis norm_zero zero_neq_one)
   ultimately show ?thesis
     using that by blast
 next
   case False
   then obtain c S' where "c \<notin> S'" "S = insert c S'"
     by (meson equals0I mk_disjoint_insert)
   have "dim ((+) (-c) ` S) < DIM('a)"
     by (metis \<open>S = insert c S'\<close> aff_dim_eq_dim assms hull_inc insertI1 of_nat_less_imp_less)
   then obtain a where "a \<noteq> 0" "span ((+) (-c) ` S) \<subseteq> {x. a \<bullet> x = 0}"
     using lowdim_subset_hyperplane by blast
   moreover
   have "a \<bullet> w = a \<bullet> c" if "span ((+) (- c) ` S) \<subseteq> {x. a \<bullet> x = 0}" "w \<in> S" for w
   proof -
     have "w-c \<in> span ((+) (- c) ` S)"
       by (simp add: span_base \<open>w \<in> S\<close>)
     with that have "w-c \<in> {x. a \<bullet> x = 0}"
       by blast
     then show ?thesis
       by (auto simp: algebra_simps)
   qed
   ultimately have "S \<subseteq> {x. a \<bullet> x = a \<bullet> c}"
     by blast
   then show ?thesis
     by (rule that[OF \<open>a \<noteq> 0\<close>])
 qed
 
 lemma affine_independent_card_dim_diffs:
   fixes S :: "'a :: euclidean_space set"
   assumes "\<not> affine_dependent S" "a \<in> S"
     shows "card S = dim {x - a|x. x \<in> S} + 1"
 proof -
   have 1: "{b - a|b. b \<in> (S - {a})} \<subseteq> {x - a|x. x \<in> S}" by auto
   have 2: "x - a \<in> span {b - a |b. b \<in> S - {a}}" if "x \<in> S" for x
   proof (cases "x = a")
     case True then show ?thesis by (simp add: span_clauses)
   next
     case False then show ?thesis
       using assms by (blast intro: span_base that)
   qed
   have "\<not> affine_dependent (insert a S)"
     by (simp add: assms insert_absorb)
   then have 3: "independent {b - a |b. b \<in> S - {a}}"
       using dependent_imp_affine_dependent by fastforce
   have "{b - a |b. b \<in> S - {a}} = (\<lambda>b. b-a) ` (S - {a})"
     by blast
   then have "card {b - a |b. b \<in> S - {a}} = card ((\<lambda>b. b-a) ` (S - {a}))"
     by simp
   also have "\<dots> = card (S - {a})"
     by (metis (no_types, lifting) card_image diff_add_cancel inj_onI)
   also have "\<dots> = card S - 1"
     by (simp add: aff_independent_finite assms)
   finally have 4: "card {b - a |b. b \<in> S - {a}} = card S - 1" .
   have "finite S"
     by (meson assms aff_independent_finite)
   with \<open>a \<in> S\<close> have "card S \<noteq> 0" by auto
   moreover have "dim {x - a |x. x \<in> S} = card S - 1"
     using 2 by (blast intro: dim_unique [OF 1 _ 3 4])
   ultimately show ?thesis
     by auto
 qed
 
 lemma independent_card_le_aff_dim:
   fixes B :: "'n::euclidean_space set"
   assumes "B \<subseteq> V"
   assumes "\<not> affine_dependent B"
   shows "int (card B) \<le> aff_dim V + 1"
 proof -
   obtain T where T: "\<not> affine_dependent T \<and> B \<subseteq> T \<and> T \<subseteq> V \<and> affine hull T = affine hull V"
     by (metis assms extend_to_affine_basis[of B V])
   then have "of_nat (card T) = aff_dim V + 1"
     using aff_dim_unique by auto
   then show ?thesis
     using T card_mono[of T B] aff_independent_finite[of T] by auto
 qed
 
 lemma aff_dim_subset:
   fixes S T :: "'n::euclidean_space set"
   assumes "S \<subseteq> T"
   shows "aff_dim S \<le> aff_dim T"
 proof -
   obtain B where B: "\<not> affine_dependent B" "B \<subseteq> S" "affine hull B = affine hull S"
     "of_nat (card B) = aff_dim S + 1"
     using aff_dim_inner_basis_exists[of S] by auto
   then have "int (card B) \<le> aff_dim T + 1"
     using assms independent_card_le_aff_dim[of B T] by auto
   with B show ?thesis by auto
 qed
 
 lemma aff_dim_le_DIM:
   fixes S :: "'n::euclidean_space set"
   shows "aff_dim S \<le> int (DIM('n))"
 proof -
   have "aff_dim (UNIV :: 'n::euclidean_space set) = int(DIM('n))"
     using aff_dim_UNIV by auto
   then show "aff_dim (S:: 'n::euclidean_space set) \<le> int(DIM('n))"
     using aff_dim_subset[of S "(UNIV :: ('n::euclidean_space) set)"] subset_UNIV by auto
 qed
 
 lemma affine_dim_equal:
   fixes S :: "'n::euclidean_space set"
   assumes "affine S" "affine T" "S \<noteq> {}" "S \<subseteq> T" "aff_dim S = aff_dim T"
   shows "S = T"
 proof -
   obtain a where "a \<in> S" using assms by auto
   then have "a \<in> T" using assms by auto
   define LS where "LS = {y. \<exists>x \<in> S. (-a) + x = y}"
   then have ls: "subspace LS" "affine_parallel S LS"
     using assms parallel_subspace_explicit[of S a LS] \<open>a \<in> S\<close> by auto
   then have h1: "int(dim LS) = aff_dim S"
     using assms aff_dim_affine[of S LS] by auto
   have "T \<noteq> {}" using assms by auto
   define LT where "LT = {y. \<exists>x \<in> T. (-a) + x = y}"
   then have lt: "subspace LT \<and> affine_parallel T LT"
     using assms parallel_subspace_explicit[of T a LT] \<open>a \<in> T\<close> by auto
   then have "int(dim LT) = aff_dim T"
     using assms aff_dim_affine[of T LT] \<open>T \<noteq> {}\<close> by auto
   then have "dim LS = dim LT"
     using h1 assms by auto
   moreover have "LS \<le> LT"
     using LS_def LT_def assms by auto
   ultimately have "LS = LT"
     using subspace_dim_equal[of LS LT] ls lt by auto
   moreover have "S = {x. \<exists>y \<in> LS. a+y=x}"
     using LS_def by auto
   moreover have "T = {x. \<exists>y \<in> LT. a+y=x}"
     using LT_def by auto
   ultimately show ?thesis by auto
 qed
 
 lemma aff_dim_eq_0:
   fixes S :: "'a::euclidean_space set"
   shows "aff_dim S = 0 \<longleftrightarrow> (\<exists>a. S = {a})"
 proof (cases "S = {}")
   case True
   then show ?thesis
     by auto
 next
   case False
   then obtain a where "a \<in> S" by auto
   show ?thesis
   proof safe
     assume 0: "aff_dim S = 0"
     have "\<not> {a,b} \<subseteq> S" if "b \<noteq> a" for b
       by (metis "0" aff_dim_2 aff_dim_subset not_one_le_zero that)
     then show "\<exists>a. S = {a}"
       using \<open>a \<in> S\<close> by blast
   qed auto
 qed
 
 lemma affine_hull_UNIV:
   fixes S :: "'n::euclidean_space set"
   assumes "aff_dim S = int(DIM('n))"
   shows "affine hull S = (UNIV :: ('n::euclidean_space) set)"
 proof -
   have "S \<noteq> {}"
     using assms aff_dim_empty[of S] by auto
   have h0: "S \<subseteq> affine hull S"
     using hull_subset[of S _] by auto
   have h1: "aff_dim (UNIV :: ('n::euclidean_space) set) = aff_dim S"
     using aff_dim_UNIV assms by auto
   then have h2: "aff_dim (affine hull S) \<le> aff_dim (UNIV :: ('n::euclidean_space) set)"
     using aff_dim_le_DIM[of "affine hull S"] assms h0 by auto
   have h3: "aff_dim S \<le> aff_dim (affine hull S)"
     using h0 aff_dim_subset[of S "affine hull S"] assms by auto
   then have h4: "aff_dim (affine hull S) = aff_dim (UNIV :: ('n::euclidean_space) set)"
     using h0 h1 h2 by auto
   then show ?thesis
     using affine_dim_equal[of "affine hull S" "(UNIV :: ('n::euclidean_space) set)"]
       affine_affine_hull[of S] affine_UNIV assms h4 h0 \<open>S \<noteq> {}\<close>
     by auto
 qed
 
 lemma disjoint_affine_hull:
   fixes s :: "'n::euclidean_space set"
   assumes "\<not> affine_dependent s" "t \<subseteq> s" "u \<subseteq> s" "t \<inter> u = {}"
     shows "(affine hull t) \<inter> (affine hull u) = {}"
 proof -
   have "finite s" using assms by (simp add: aff_independent_finite)
   then have "finite t" "finite u" using assms finite_subset by blast+
   { fix y
     assume yt: "y \<in> affine hull t" and yu: "y \<in> affine hull u"
     then obtain a b
            where a1 [simp]: "sum a t = 1" and [simp]: "sum (\<lambda>v. a v *\<^sub>R v) t = y"
              and [simp]: "sum b u = 1" "sum (\<lambda>v. b v *\<^sub>R v) u = y"
       by (auto simp: affine_hull_finite \<open>finite t\<close> \<open>finite u\<close>)
     define c where "c x = (if x \<in> t then a x else if x \<in> u then -(b x) else 0)" for x
     have [simp]: "s \<inter> t = t" "s \<inter> - t \<inter> u = u" using assms by auto
     have "sum c s = 0"
       by (simp add: c_def comm_monoid_add_class.sum.If_cases \<open>finite s\<close> sum_negf)
     moreover have "\<not> (\<forall>v\<in>s. c v = 0)"
       by (metis (no_types) IntD1 \<open>s \<inter> t = t\<close> a1 c_def sum.neutral zero_neq_one)
     moreover have "(\<Sum>v\<in>s. c v *\<^sub>R v) = 0"
       by (simp add: c_def if_smult sum_negf
              comm_monoid_add_class.sum.If_cases \<open>finite s\<close>)
     ultimately have False
       using assms \<open>finite s\<close> by (auto simp: affine_dependent_explicit)
   }
   then show ?thesis by blast
 qed
 
 end
\ No newline at end of file