Theory RComplete (Isabelle2005: October 2005)

# Theory RComplete

Up to index of Isabelle/HOL/HOL-Complex

theory RComplete
imports Lubs RealDef
begin

    (*  Title       : HOL/Real/RComplete.thy
        ID          : $Id: RComplete.thy,v 1.16 2005/07/19 18:47:00 wenzelm Exp $
        Author      : Jacques D. Fleuriot, University of Edinburgh
        Author      : Larry Paulson, University of Cambridge
        Author      : Jeremy Avigad, Carnegie Mellon University
        Author      : Florian Zuleger, Johannes Hoelzl, and Simon Funke, TU Muenchen
    *)

    header {* Completeness of the Reals; Floor and Ceiling Functions *}

    theory RComplete
    imports Lubs RealDef
    begin

    lemma real_sum_of_halves: "x/2 + x/2 = (x::real)"
      by simp

    subsection {* Completeness of Positive Reals *}

    text {*
      Supremum property for the set of positive reals

      Let @{text "P"} be a non-empty set of positive reals, with an upper
      bound @{text "y"}.  Then @{text "P"} has a least upper bound
      (written @{text "S"}).

      FIXME: Can the premise be weakened to @{text "∀x ∈ P. x≤ y"}?
    *}

    lemma posreal_complete:
      assumes positive_P: "∀x ∈ P. (0::real) < x"
        and not_empty_P: "∃x. x ∈ P"
        and upper_bound_Ex: "∃y. ∀x ∈ P. x<y"
      shows "∃S. ∀y. (∃x ∈ P. y < x) = (y < S)"
    proof (rule exI, rule allI)
      fix y
      let ?pP = "{w. real_of_preal w ∈ P}"

      show "(∃x∈P. y < x) = (y < real_of_preal (psup ?pP))"
      proof (cases "0 < y")
        assume neg_y: "¬ 0 < y"
        show ?thesis
        proof
          assume "∃x∈P. y < x"
          have "∀x. y < real_of_preal x"
            using neg_y by (rule real_less_all_real2)
          thus "y < real_of_preal (psup ?pP)" ..
        next
          assume "y < real_of_preal (psup ?pP)"
          obtain "x" where x_in_P: "x ∈ P" using not_empty_P ..
          hence "0 < x" using positive_P by simp
          hence "y < x" using neg_y by simp
          thus "∃x ∈ P. y < x" using x_in_P ..
        qed
      next
        assume pos_y: "0 < y"

        then obtain py where y_is_py: "y = real_of_preal py"
          by (auto simp add: real_gt_zero_preal_Ex)

        obtain a where a_in_P: "a ∈ P" using not_empty_P ..
        have a_pos: "0 < a" using positive_P ..
        then obtain pa where "a = real_of_preal pa"
          by (auto simp add: real_gt_zero_preal_Ex)
        hence "pa ∈ ?pP" using a_in_P by auto
        hence pP_not_empty: "?pP ≠ {}" by auto

        obtain sup where sup: "∀x ∈ P. x < sup"
          using upper_bound_Ex ..
        hence  "a < sup" ..
        hence "0 < sup" using a_pos by arith
        then obtain possup where "sup = real_of_preal possup"
          by (auto simp add: real_gt_zero_preal_Ex)
        hence "∀X ∈ ?pP. X ≤ possup"
          using sup by (auto simp add: real_of_preal_lessI)
        with pP_not_empty have psup: "!!Z. (∃X ∈ ?pP. Z < X) = (Z < psup ?pP)"
          by (rule preal_complete)

        show ?thesis
        proof
          assume "∃x ∈ P. y < x"
          then obtain x where x_in_P: "x ∈ P" and y_less_x: "y < x" ..
          hence "0 < x" using pos_y by arith
          then obtain px where x_is_px: "x = real_of_preal px"
            by (auto simp add: real_gt_zero_preal_Ex)

          have py_less_X: "∃X ∈ ?pP. py < X"
          proof
            show "py < px" using y_is_py and x_is_px and y_less_x
              by (simp add: real_of_preal_lessI)
            show "px ∈ ?pP" using x_in_P and x_is_px by simp
          qed

          have "(∃X ∈ ?pP. py < X) ==> (py < psup ?pP)"
            using psup by simp
          hence "py < psup ?pP" using py_less_X by simp
          thus "y < real_of_preal (psup {w. real_of_preal w ∈ P})"
            using y_is_py and pos_y by (simp add: real_of_preal_lessI)
        next
          assume y_less_psup: "y < real_of_preal (psup ?pP)"

          hence "py < psup ?pP" using y_is_py
            by (simp add: real_of_preal_lessI)
          then obtain "X" where py_less_X: "py < X" and X_in_pP: "X ∈ ?pP"
            using psup by auto
          then obtain x where x_is_X: "x = real_of_preal X"
            by (simp add: real_gt_zero_preal_Ex)
          hence "y < x" using py_less_X and y_is_py
            by (simp add: real_of_preal_lessI)

          moreover have "x ∈ P" using x_is_X and X_in_pP by simp

          ultimately show "∃ x ∈ P. y < x" ..
        qed
      qed
    qed

    text {*
      \medskip Completeness properties using @{text "isUb"}, @{text "isLub"} etc.
    *}

    lemma real_isLub_unique: "[| isLub R S x; isLub R S y |] ==> x = (y::real)"
      apply (frule isLub_isUb)
      apply (frule_tac x = y in isLub_isUb)
      apply (blast intro!: order_antisym dest!: isLub_le_isUb)
      done

    text {*
      \medskip Completeness theorem for the positive reals (again).
    *}

    lemma posreals_complete:
      assumes positive_S: "∀x ∈ S. 0 < x"
        and not_empty_S: "∃x. x ∈ S"
        and upper_bound_Ex: "∃u. isUb (UNIV::real set) S u"
      shows "∃t. isLub (UNIV::real set) S t"
    proof
      let ?pS = "{w. real_of_preal w ∈ S}"

      obtain u where "isUb UNIV S u" using upper_bound_Ex ..
      hence sup: "∀x ∈ S. x ≤ u" by (simp add: isUb_def setle_def)

      obtain x where x_in_S: "x ∈ S" using not_empty_S ..
      hence x_gt_zero: "0 < x" using positive_S by simp
      have  "x ≤ u" using sup and x_in_S ..
      hence "0 < u" using x_gt_zero by arith

      then obtain pu where u_is_pu: "u = real_of_preal pu"
        by (auto simp add: real_gt_zero_preal_Ex)

      have pS_less_pu: "∀pa ∈ ?pS. pa ≤ pu"
      proof
        fix pa
        assume "pa ∈ ?pS"
        then obtain a where "a ∈ S" and "a = real_of_preal pa"
          by simp
        moreover hence "a ≤ u" using sup by simp
        ultimately show "pa ≤ pu"
          using sup and u_is_pu by (simp add: real_of_preal_le_iff)
      qed

      have "∀y ∈ S. y ≤ real_of_preal (psup ?pS)"
      proof
        fix y
        assume y_in_S: "y ∈ S"
        hence "0 < y" using positive_S by simp
        then obtain py where y_is_py: "y = real_of_preal py"
          by (auto simp add: real_gt_zero_preal_Ex)
        hence py_in_pS: "py ∈ ?pS" using y_in_S by simp
        with pS_less_pu have "py ≤ psup ?pS"
          by (rule preal_psup_le)
        thus "y ≤ real_of_preal (psup ?pS)"
          using y_is_py by (simp add: real_of_preal_le_iff)
      qed

      moreover {
        fix x
        assume x_ub_S: "∀y∈S. y ≤ x"
        have "real_of_preal (psup ?pS) ≤ x"
        proof -
          obtain "s" where s_in_S: "s ∈ S" using not_empty_S ..
          hence s_pos: "0 < s" using positive_S by simp

          hence "∃ ps. s = real_of_preal ps" by (simp add: real_gt_zero_preal_Ex)
          then obtain "ps" where s_is_ps: "s = real_of_preal ps" ..
          hence ps_in_pS: "ps ∈ {w. real_of_preal w ∈ S}" using s_in_S by simp

          from x_ub_S have "s ≤ x" using s_in_S ..
          hence "0 < x" using s_pos by simp
          hence "∃ px. x = real_of_preal px" by (simp add: real_gt_zero_preal_Ex)
          then obtain "px" where x_is_px: "x = real_of_preal px" ..

          have "∀pe ∈ ?pS. pe ≤ px"
          proof
            fix pe
            assume "pe ∈ ?pS"
            hence "real_of_preal pe ∈ S" by simp
            hence "real_of_preal pe ≤ x" using x_ub_S by simp
            thus "pe ≤ px" using x_is_px by (simp add: real_of_preal_le_iff)
          qed

          moreover have "?pS ≠ {}" using ps_in_pS by auto
          ultimately have "(psup ?pS) ≤ px" by (simp add: psup_le_ub)
          thus "real_of_preal (psup ?pS) ≤ x" using x_is_px by (simp add: real_of_preal_le_iff)
        qed
      }
      ultimately show "isLub UNIV S (real_of_preal (psup ?pS))"
        by (simp add: isLub_def leastP_def isUb_def setle_def setge_def)
    qed

    text {*
      \medskip reals Completeness (again!)
    *}

    lemma reals_complete:
      assumes notempty_S: "∃X. X ∈ S"
        and exists_Ub: "∃Y. isUb (UNIV::real set) S Y"
      shows "∃t. isLub (UNIV :: real set) S t"
    proof -
      obtain X where X_in_S: "X ∈ S" using notempty_S ..
      obtain Y where Y_isUb: "isUb (UNIV::real set) S Y"
        using exists_Ub ..
      let ?SHIFT = "{z. ∃x ∈S. z = x + (-X) + 1} ∩ {x. 0 < x}"

      {
        fix x
        assume "isUb (UNIV::real set) S x"
        hence S_le_x: "∀ y ∈ S. y <= x"
          by (simp add: isUb_def setle_def)
        {
          fix s
          assume "s ∈ {z. ∃x∈S. z = x + - X + 1}"
          hence "∃ x ∈ S. s = x + -X + 1" ..
          then obtain x1 where "x1 ∈ S" and "s = x1 + (-X) + 1" ..
          moreover hence "x1 ≤ x" using S_le_x by simp
          ultimately have "s ≤ x + - X + 1" by arith
        }
        then have "isUb (UNIV::real set) ?SHIFT (x + (-X) + 1)"
          by (auto simp add: isUb_def setle_def)
      } note S_Ub_is_SHIFT_Ub = this

      hence "isUb UNIV ?SHIFT (Y + (-X) + 1)" using Y_isUb by simp
      hence "∃Z. isUb UNIV ?SHIFT Z" ..
      moreover have "∀y ∈ ?SHIFT. 0 < y" by auto
      moreover have shifted_not_empty: "∃u. u ∈ ?SHIFT"
        using X_in_S and Y_isUb by auto
      ultimately obtain t where t_is_Lub: "isLub UNIV ?SHIFT t"
        using posreals_complete [of ?SHIFT] by blast

      show ?thesis
      proof
        show "isLub UNIV S (t + X + (-1))"
        proof (rule isLubI2)
          {
            fix x
            assume "isUb (UNIV::real set) S x"
            hence "isUb (UNIV::real set) (?SHIFT) (x + (-X) + 1)"
              using S_Ub_is_SHIFT_Ub by simp
            hence "t ≤ (x + (-X) + 1)"
              using t_is_Lub by (simp add: isLub_le_isUb)
            hence "t + X + -1 ≤ x" by arith
          }
          then show "(t + X + -1) <=* Collect (isUb UNIV S)"
            by (simp add: setgeI)
        next
          show "isUb UNIV S (t + X + -1)"
          proof -
            {
              fix y
              assume y_in_S: "y ∈ S"
              have "y ≤ t + X + -1"
              proof -
                obtain "u" where u_in_shift: "u ∈ ?SHIFT" using shifted_not_empty ..
                hence "∃ x ∈ S. u = x + - X + 1" by simp
                then obtain "x" where x_and_u: "u = x + - X + 1" ..
                have u_le_t: "u ≤ t" using u_in_shift and t_is_Lub by (simp add: isLubD2)

                show ?thesis
                proof cases
                  assume "y ≤ x"
                  moreover have "x = u + X + - 1" using x_and_u by arith
                  moreover have "u + X + - 1  ≤ t + X + -1" using u_le_t by arith
                  ultimately show "y  ≤ t + X + -1" by arith
                next
                  assume "~(y ≤ x)"
                  hence x_less_y: "x < y" by arith

                  have "x + (-X) + 1 ∈ ?SHIFT" using x_and_u and u_in_shift by simp
                  hence "0 < x + (-X) + 1" by simp
                  hence "0 < y + (-X) + 1" using x_less_y by arith
                  hence "y + (-X) + 1 ∈ ?SHIFT" using y_in_S by simp
                  hence "y + (-X) + 1 ≤ t" using t_is_Lub  by (simp add: isLubD2)
                  thus ?thesis by simp
                qed
              qed
            }
            then show ?thesis by (simp add: isUb_def setle_def)
          qed
        qed
      qed
    qed

    subsection {* The Archimedean Property of the Reals *}

    theorem reals_Archimedean:
      assumes x_pos: "0 < x"
      shows "∃n. inverse (real (Suc n)) < x"
    proof (rule ccontr)
      assume contr: "¬ ?thesis"
      have "∀n. x * real (Suc n) <= 1"
      proof
        fix n
        from contr have "x ≤ inverse (real (Suc n))"
          by (simp add: linorder_not_less)
        hence "x ≤ (1 / (real (Suc n)))"
          by (simp add: inverse_eq_divide)
        moreover have "0 ≤ real (Suc n)"
          by (rule real_of_nat_ge_zero)
        ultimately have "x * real (Suc n) ≤ (1 / real (Suc n)) * real (Suc n)"
          by (rule mult_right_mono)
        thus "x * real (Suc n) ≤ 1" by simp
      qed
      hence "{z. ∃n. z = x * (real (Suc n))} *<= 1"
        by (simp add: setle_def, safe, rule spec)
      hence "isUb (UNIV::real set) {z. ∃n. z = x * (real (Suc n))} 1"
        by (simp add: isUbI)
      hence "∃Y. isUb (UNIV::real set) {z. ∃n. z = x* (real (Suc n))} Y" ..
      moreover have "∃X. X ∈ {z. ∃n. z = x* (real (Suc n))}" by auto
      ultimately have "∃t. isLub UNIV {z. ∃n. z = x * real (Suc n)} t"
        by (simp add: reals_complete)
      then obtain "t" where
        t_is_Lub: "isLub UNIV {z. ∃n. z = x * real (Suc n)} t" ..

      have "∀n::nat. x * real n ≤ t + - x"
      proof
        fix n
        from t_is_Lub have "x * real (Suc n) ≤ t"
          by (simp add: isLubD2)
        hence  "x * (real n) + x ≤ t"
          by (simp add: right_distrib real_of_nat_Suc)
        thus  "x * (real n) ≤ t + - x" by arith
      qed

      hence "∀m. x * real (Suc m) ≤ t + - x" by simp
      hence "{z. ∃n. z = x * (real (Suc n))}  *<= (t + - x)"
        by (auto simp add: setle_def)
      hence "isUb (UNIV::real set) {z. ∃n. z = x * (real (Suc n))} (t + (-x))"
        by (simp add: isUbI)
      hence "t ≤ t + - x"
        using t_is_Lub by (simp add: isLub_le_isUb)
      thus False using x_pos by arith
    qed

    text {*
      There must be other proofs, e.g. @{text "Suc"} of the largest
      integer in the cut representing @{text "x"}.
    *}

    lemma reals_Archimedean2: "∃n. (x::real) < real (n::nat)"
    proof cases
      assume "x ≤ 0"
      hence "x < real (1::nat)" by simp
      thus ?thesis ..
    next
      assume "¬ x ≤ 0"
      hence x_greater_zero: "0 < x" by simp
      hence "0 < inverse x" by simp
      then obtain n where "inverse (real (Suc n)) < inverse x"
        using reals_Archimedean by blast
      hence "inverse (real (Suc n)) * x < inverse x * x"
        using x_greater_zero by (rule mult_strict_right_mono)
      hence "inverse (real (Suc n)) * x < 1"
        using x_greater_zero by (simp add: real_mult_inverse_left mult_commute)
      hence "real (Suc n) * (inverse (real (Suc n)) * x) < real (Suc n) * 1"
        by (rule mult_strict_left_mono) simp
      hence "x < real (Suc n)"
        by (simp add: mult_commute ring_eq_simps real_mult_inverse_left)
      thus "∃(n::nat). x < real n" ..
    qed

    lemma reals_Archimedean3:
      assumes x_greater_zero: "0 < x"
      shows "∀(y::real). ∃(n::nat). y < real n * x"
    proof
      fix y
      have x_not_zero: "x ≠ 0" using x_greater_zero by simp
      obtain n where "y * inverse x < real (n::nat)"
        using reals_Archimedean2 ..
      hence "y * inverse x * x < real n * x"
        using x_greater_zero by (simp add: mult_strict_right_mono)
      hence "x * inverse x * y < x * real n"
        by (simp add: mult_commute ring_eq_simps)
      hence "y < real (n::nat) * x"
        using x_not_zero by (simp add: real_mult_inverse_left ring_eq_simps)
      thus "∃(n::nat). y < real n * x" ..
    qed

    lemma reals_Archimedean6:
         "0 ≤ r ==> ∃(n::nat). real (n - 1) ≤ r & r < real (n)"
    apply (insert reals_Archimedean2 [of r], safe)
    apply (frule_tac P = "%k. r < real k" and k = n and m = "%x. x"
           in ex_has_least_nat, auto)
    apply (rule_tac x = x in exI)
    apply (case_tac x, simp)
    apply (rename_tac x')
    apply (drule_tac x = x' in spec, simp)
    done

    lemma reals_Archimedean6a: "0 ≤ r ==> ∃n. real (n) ≤ r & r < real (Suc n)"
      by (drule reals_Archimedean6) auto

    lemma reals_Archimedean_6b_int:
         "0 ≤ r ==> ∃n::int. real n ≤ r & r < real (n+1)"
    apply (drule reals_Archimedean6a, auto)
    apply (rule_tac x = "int n" in exI)
    apply (simp add: real_of_int_real_of_nat real_of_nat_Suc)
    done

    lemma reals_Archimedean_6c_int:
         "r < 0 ==> ∃n::int. real n ≤ r & r < real (n+1)"
    apply (rule reals_Archimedean_6b_int [of "-r", THEN exE], simp, auto)
    apply (rename_tac n)
    apply (drule real_le_imp_less_or_eq, auto)
    apply (rule_tac x = "- n - 1" in exI)
    apply (rule_tac [2] x = "- n" in exI, auto)
    done

    ML
    {*
    val real_sum_of_halves = thm "real_sum_of_halves";
    val posreal_complete = thm "posreal_complete";
    val real_isLub_unique = thm "real_isLub_unique";
    val posreals_complete = thm "posreals_complete";
    val reals_complete = thm "reals_complete";
    val reals_Archimedean = thm "reals_Archimedean";
    val reals_Archimedean2 = thm "reals_Archimedean2";
    val reals_Archimedean3 = thm "reals_Archimedean3";
    *}

    subsection{*Floor and Ceiling Functions from the Reals to the Integers*}

    constdefs

      floor :: "real => int"
       "floor r == (LEAST n::int. r < real (n+1))"

      ceiling :: "real => int"
        "ceiling r == - floor (- r)"

    syntax (xsymbols)
      floor :: "real => int"     ("⌊_⌋")
      ceiling :: "real => int"   ("⌈_⌉")

    syntax (HTML output)
      floor :: "real => int"     ("⌊_⌋")
      ceiling :: "real => int"   ("⌈_⌉")

    lemma number_of_less_real_of_int_iff [simp]:
         "((number_of n) < real (m::int)) = (number_of n < m)"
    apply auto
    apply (rule real_of_int_less_iff [THEN iffD1])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD2], auto)
    done

    lemma number_of_less_real_of_int_iff2 [simp]:
         "(real (m::int) < (number_of n)) = (m < number_of n)"
    apply auto
    apply (rule real_of_int_less_iff [THEN iffD1])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD2], auto)
    done

    lemma number_of_le_real_of_int_iff [simp]:
         "((number_of n) ≤ real (m::int)) = (number_of n ≤ m)"
    by (simp add: linorder_not_less [symmetric])

    lemma number_of_le_real_of_int_iff2 [simp]:
         "(real (m::int) ≤ (number_of n)) = (m ≤ number_of n)"
    by (simp add: linorder_not_less [symmetric])

    lemma floor_zero [simp]: "floor 0 = 0"
    apply (simp add: floor_def del: real_of_int_add)
    apply (rule Least_equality)
    apply simp_all
    done

    lemma floor_real_of_nat_zero [simp]: "floor (real (0::nat)) = 0"
    by auto

    lemma floor_real_of_nat [simp]: "floor (real (n::nat)) = int n"
    apply (simp only: floor_def)
    apply (rule Least_equality)
    apply (drule_tac [2] real_of_int_real_of_nat [THEN ssubst])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD1])
    apply (simp_all add: real_of_int_real_of_nat)
    done

    lemma floor_minus_real_of_nat [simp]: "floor (- real (n::nat)) = - int n"
    apply (simp only: floor_def)
    apply (rule Least_equality)
    apply (drule_tac [2] real_of_int_real_of_nat [THEN ssubst])
    apply (drule_tac [2] real_of_int_minus [THEN sym, THEN subst])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD1])
    apply (simp_all add: real_of_int_real_of_nat)
    done

    lemma floor_real_of_int [simp]: "floor (real (n::int)) = n"
    apply (simp only: floor_def)
    apply (rule Least_equality)
    apply (drule_tac [2] real_of_int_real_of_nat [THEN ssubst])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD1], auto)
    done

    lemma floor_minus_real_of_int [simp]: "floor (- real (n::int)) = - n"
    apply (simp only: floor_def)
    apply (rule Least_equality)
    apply (drule_tac [2] real_of_int_minus [THEN sym, THEN subst])
    apply (drule_tac [2] real_of_int_real_of_nat [THEN ssubst])
    apply (drule_tac [2] real_of_int_less_iff [THEN iffD1], auto)
    done

    lemma real_lb_ub_int: " ∃n::int. real n ≤ r & r < real (n+1)"
    apply (case_tac "r < 0")
    apply (blast intro: reals_Archimedean_6c_int)
    apply (simp only: linorder_not_less)
    apply (blast intro: reals_Archimedean_6b_int reals_Archimedean_6c_int)
    done

    lemma lemma_floor:
      assumes a1: "real m ≤ r" and a2: "r < real n + 1"
      shows "m ≤ (n::int)"
    proof -
      have "real m < real n + 1" by (rule order_le_less_trans)
      also have "... = real(n+1)" by simp
      finally have "m < n+1" by (simp only: real_of_int_less_iff)
      thus ?thesis by arith
    qed

    lemma real_of_int_floor_le [simp]: "real (floor r) ≤ r"
    apply (simp add: floor_def Least_def)
    apply (insert real_lb_ub_int [of r], safe)
    apply (rule theI2)
    apply auto
    done

    lemma floor_mono: "x < y ==> floor x ≤ floor y"
    apply (simp add: floor_def Least_def)
    apply (insert real_lb_ub_int [of x])
    apply (insert real_lb_ub_int [of y], safe)
    apply (rule theI2)
    apply (rule_tac [3] theI2)
    apply simp
    apply (erule conjI)
    apply (auto simp add: order_eq_iff int_le_real_less)
    done

    lemma floor_mono2: "x ≤ y ==> floor x ≤ floor y"
    by (auto dest: real_le_imp_less_or_eq simp add: floor_mono)

    lemma lemma_floor2: "real n < real (x::int) + 1 ==> n ≤ x"
    by (auto intro: lemma_floor)

    lemma real_of_int_floor_cancel [simp]:
        "(real (floor x) = x) = (∃n::int. x = real n)"
    apply (simp add: floor_def Least_def)
    apply (insert real_lb_ub_int [of x], erule exE)
    apply (rule theI2)
    apply (auto intro: lemma_floor)
    done

    lemma floor_eq: "[| real n < x; x < real n + 1 |] ==> floor x = n"
    apply (simp add: floor_def)
    apply (rule Least_equality)
    apply (auto intro: lemma_floor)
    done

    lemma floor_eq2: "[| real n ≤ x; x < real n + 1 |] ==> floor x = n"
    apply (simp add: floor_def)
    apply (rule Least_equality)
    apply (auto intro: lemma_floor)
    done

    lemma floor_eq3: "[| real n < x; x < real (Suc n) |] ==> nat(floor x) = n"
    apply (rule inj_int [THEN injD])
    apply (simp add: real_of_nat_Suc)
    apply (simp add: real_of_nat_Suc floor_eq floor_eq [where n = "int n"])
    done

    lemma floor_eq4: "[| real n ≤ x; x < real (Suc n) |] ==> nat(floor x) = n"
    apply (drule order_le_imp_less_or_eq)
    apply (auto intro: floor_eq3)
    done

    lemma floor_number_of_eq [simp]:
         "floor(number_of n :: real) = (number_of n :: int)"
    apply (subst real_number_of [symmetric])
    apply (rule floor_real_of_int)
    done

    lemma floor_one [simp]: "floor 1 = 1"
      apply (rule trans)
      prefer 2
      apply (rule floor_real_of_int)
      apply simp
    done

    lemma real_of_int_floor_ge_diff_one [simp]: "r - 1 ≤ real(floor r)"
    apply (simp add: floor_def Least_def)
    apply (insert real_lb_ub_int [of r], safe)
    apply (rule theI2)
    apply (auto intro: lemma_floor)
    done

    lemma real_of_int_floor_gt_diff_one [simp]: "r - 1 < real(floor r)"
    apply (simp add: floor_def Least_def)
    apply (insert real_lb_ub_int [of r], safe)
    apply (rule theI2)
    apply (auto intro: lemma_floor)
    done

    lemma real_of_int_floor_add_one_ge [simp]: "r ≤ real(floor r) + 1"
    apply (insert real_of_int_floor_ge_diff_one [of r])
    apply (auto simp del: real_of_int_floor_ge_diff_one)
    done

    lemma real_of_int_floor_add_one_gt [simp]: "r < real(floor r) + 1"
    apply (insert real_of_int_floor_gt_diff_one [of r])
    apply (auto simp del: real_of_int_floor_gt_diff_one)
    done

    lemma le_floor: "real a <= x ==> a <= floor x"
      apply (subgoal_tac "a < floor x + 1")
      apply arith
      apply (subst real_of_int_less_iff [THEN sym])
      apply simp
      apply (insert real_of_int_floor_add_one_gt [of x])
      apply arith
    done

    lemma real_le_floor: "a <= floor x ==> real a <= x"
      apply (rule order_trans)
      prefer 2
      apply (rule real_of_int_floor_le)
      apply (subst real_of_int_le_iff)
      apply assumption
    done

    lemma le_floor_eq: "(a <= floor x) = (real a <= x)"
      apply (rule iffI)
      apply (erule real_le_floor)
      apply (erule le_floor)
    done

    lemma le_floor_eq_number_of [simp]:
        "(number_of n <= floor x) = (number_of n <= x)"
    by (simp add: le_floor_eq)

    lemma le_floor_eq_zero [simp]: "(0 <= floor x) = (0 <= x)"
    by (simp add: le_floor_eq)

    lemma le_floor_eq_one [simp]: "(1 <= floor x) = (1 <= x)"
    by (simp add: le_floor_eq)

    lemma floor_less_eq: "(floor x < a) = (x < real a)"
      apply (subst linorder_not_le [THEN sym])+
      apply simp
      apply (rule le_floor_eq)
    done

    lemma floor_less_eq_number_of [simp]:
        "(floor x < number_of n) = (x < number_of n)"
    by (simp add: floor_less_eq)

    lemma floor_less_eq_zero [simp]: "(floor x < 0) = (x < 0)"
    by (simp add: floor_less_eq)

    lemma floor_less_eq_one [simp]: "(floor x < 1) = (x < 1)"
    by (simp add: floor_less_eq)

    lemma less_floor_eq: "(a < floor x) = (real a + 1 <= x)"
      apply (insert le_floor_eq [of "a + 1" x])
      apply auto
    done

    lemma less_floor_eq_number_of [simp]:
        "(number_of n < floor x) = (number_of n + 1 <= x)"
    by (simp add: less_floor_eq)

    lemma less_floor_eq_zero [simp]: "(0 < floor x) = (1 <= x)"
    by (simp add: less_floor_eq)

    lemma less_floor_eq_one [simp]: "(1 < floor x) = (2 <= x)"
    by (simp add: less_floor_eq)

    lemma floor_le_eq: "(floor x <= a) = (x < real a + 1)"
      apply (insert floor_less_eq [of x "a + 1"])
      apply auto
    done

    lemma floor_le_eq_number_of [simp]:
        "(floor x <= number_of n) = (x < number_of n + 1)"
    by (simp add: floor_le_eq)

    lemma floor_le_eq_zero [simp]: "(floor x <= 0) = (x < 1)"
    by (simp add: floor_le_eq)

    lemma floor_le_eq_one [simp]: "(floor x <= 1) = (x < 2)"
    by (simp add: floor_le_eq)

    lemma floor_add [simp]: "floor (x + real a) = floor x + a"
      apply (subst order_eq_iff)
      apply (rule conjI)
      prefer 2
      apply (subgoal_tac "floor x + a < floor (x + real a) + 1")
      apply arith
      apply (subst real_of_int_less_iff [THEN sym])
      apply simp
      apply (subgoal_tac "x + real a < real(floor(x + real a)) + 1")
      apply (subgoal_tac "real (floor x) <= x")
      apply arith
      apply (rule real_of_int_floor_le)
      apply (rule real_of_int_floor_add_one_gt)
      apply (subgoal_tac "floor (x + real a) < floor x + a + 1")
      apply arith
      apply (subst real_of_int_less_iff [THEN sym])
      apply simp
      apply (subgoal_tac "real(floor(x + real a)) <= x + real a")
      apply (subgoal_tac "x < real(floor x) + 1")
      apply arith
      apply (rule real_of_int_floor_add_one_gt)
      apply (rule real_of_int_floor_le)
    done

    lemma floor_add_number_of [simp]:
        "floor (x + number_of n) = floor x + number_of n"
      apply (subst floor_add [THEN sym])
      apply simp
    done

    lemma floor_add_one [simp]: "floor (x + 1) = floor x + 1"
      apply (subst floor_add [THEN sym])
      apply simp
    done

    lemma floor_subtract [simp]: "floor (x - real a) = floor x - a"
      apply (subst diff_minus)+
      apply (subst real_of_int_minus [THEN sym])
      apply (rule floor_add)
    done

    lemma floor_subtract_number_of [simp]: "floor (x - number_of n) =
        floor x - number_of n"
      apply (subst floor_subtract [THEN sym])
      apply simp
    done

    lemma floor_subtract_one [simp]: "floor (x - 1) = floor x - 1"
      apply (subst floor_subtract [THEN sym])
      apply simp
    done

    lemma ceiling_zero [simp]: "ceiling 0 = 0"
    by (simp add: ceiling_def)

    lemma ceiling_real_of_nat [simp]: "ceiling (real (n::nat)) = int n"
    by (simp add: ceiling_def)

    lemma ceiling_real_of_nat_zero [simp]: "ceiling (real (0::nat)) = 0"
    by auto

    lemma ceiling_floor [simp]: "ceiling (real (floor r)) = floor r"
    by (simp add: ceiling_def)

    lemma floor_ceiling [simp]: "floor (real (ceiling r)) = ceiling r"
    by (simp add: ceiling_def)

    lemma real_of_int_ceiling_ge [simp]: "r ≤ real (ceiling r)"
    apply (simp add: ceiling_def)
    apply (subst le_minus_iff, simp)
    done

    lemma ceiling_mono: "x < y ==> ceiling x ≤ ceiling y"
    by (simp add: floor_mono ceiling_def)

    lemma ceiling_mono2: "x ≤ y ==> ceiling x ≤ ceiling y"
    by (simp add: floor_mono2 ceiling_def)

    lemma real_of_int_ceiling_cancel [simp]:
         "(real (ceiling x) = x) = (∃n::int. x = real n)"
    apply (auto simp add: ceiling_def)
    apply (drule arg_cong [where f = uminus], auto)
    apply (rule_tac x = "-n" in exI, auto)
    done

    lemma ceiling_eq: "[| real n < x; x < real n + 1 |] ==> ceiling x = n + 1"
    apply (simp add: ceiling_def)
    apply (rule minus_equation_iff [THEN iffD1])
    apply (simp add: floor_eq [where n = "-(n+1)"])
    done

    lemma ceiling_eq2: "[| real n < x; x ≤ real n + 1 |] ==> ceiling x = n + 1"
    by (simp add: ceiling_def floor_eq2 [where n = "-(n+1)"])

    lemma ceiling_eq3: "[| real n - 1 < x; x ≤ real n  |] ==> ceiling x = n"
    by (simp add: ceiling_def floor_eq2 [where n = "-n"])

    lemma ceiling_real_of_int [simp]: "ceiling (real (n::int)) = n"
    by (simp add: ceiling_def)

    lemma ceiling_number_of_eq [simp]:
         "ceiling (number_of n :: real) = (number_of n)"
    apply (subst real_number_of [symmetric])
    apply (rule ceiling_real_of_int)
    done

    lemma ceiling_one [simp]: "ceiling 1 = 1"
      by (unfold ceiling_def, simp)

    lemma real_of_int_ceiling_diff_one_le [simp]: "real (ceiling r) - 1 ≤ r"
    apply (rule neg_le_iff_le [THEN iffD1])
    apply (simp add: ceiling_def diff_minus)
    done

    lemma real_of_int_ceiling_le_add_one [simp]: "real (ceiling r) ≤ r + 1"
    apply (insert real_of_int_ceiling_diff_one_le [of r])
    apply (simp del: real_of_int_ceiling_diff_one_le)
    done

    lemma ceiling_le: "x <= real a ==> ceiling x <= a"
      apply (unfold ceiling_def)
      apply (subgoal_tac "-a <= floor(- x)")
      apply simp
      apply (rule le_floor)
      apply simp
    done

    lemma ceiling_le_real: "ceiling x <= a ==> x <= real a"
      apply (unfold ceiling_def)
      apply (subgoal_tac "real(- a) <= - x")
      apply simp
      apply (rule real_le_floor)
      apply simp
    done

    lemma ceiling_le_eq: "(ceiling x <= a) = (x <= real a)"
      apply (rule iffI)
      apply (erule ceiling_le_real)
      apply (erule ceiling_le)
    done

    lemma ceiling_le_eq_number_of [simp]:
        "(ceiling x <= number_of n) = (x <= number_of n)"
    by (simp add: ceiling_le_eq)

    lemma ceiling_le_zero_eq [simp]: "(ceiling x <= 0) = (x <= 0)"
    by (simp add: ceiling_le_eq)

    lemma ceiling_le_eq_one [simp]: "(ceiling x <= 1) = (x <= 1)"
    by (simp add: ceiling_le_eq)

    lemma less_ceiling_eq: "(a < ceiling x) = (real a < x)"
      apply (subst linorder_not_le [THEN sym])+
      apply simp
      apply (rule ceiling_le_eq)
    done

    lemma less_ceiling_eq_number_of [simp]:
        "(number_of n < ceiling x) = (number_of n < x)"
    by (simp add: less_ceiling_eq)

    lemma less_ceiling_eq_zero [simp]: "(0 < ceiling x) = (0 < x)"
    by (simp add: less_ceiling_eq)

    lemma less_ceiling_eq_one [simp]: "(1 < ceiling x) = (1 < x)"
    by (simp add: less_ceiling_eq)

    lemma ceiling_less_eq: "(ceiling x < a) = (x <= real a - 1)"
      apply (insert ceiling_le_eq [of x "a - 1"])
      apply auto
    done

    lemma ceiling_less_eq_number_of [simp]:
        "(ceiling x < number_of n) = (x <= number_of n - 1)"
    by (simp add: ceiling_less_eq)

    lemma ceiling_less_eq_zero [simp]: "(ceiling x < 0) = (x <= -1)"
    by (simp add: ceiling_less_eq)

    lemma ceiling_less_eq_one [simp]: "(ceiling x < 1) = (x <= 0)"
    by (simp add: ceiling_less_eq)

    lemma le_ceiling_eq: "(a <= ceiling x) = (real a - 1 < x)"
      apply (insert less_ceiling_eq [of "a - 1" x])
      apply auto
    done

    lemma le_ceiling_eq_number_of [simp]:
        "(number_of n <= ceiling x) = (number_of n - 1 < x)"
    by (simp add: le_ceiling_eq)

    lemma le_ceiling_eq_zero [simp]: "(0 <= ceiling x) = (-1 < x)"
    by (simp add: le_ceiling_eq)

    lemma le_ceiling_eq_one [simp]: "(1 <= ceiling x) = (0 < x)"
    by (simp add: le_ceiling_eq)

    lemma ceiling_add [simp]: "ceiling (x + real a) = ceiling x + a"
      apply (unfold ceiling_def, simp)
      apply (subst real_of_int_minus [THEN sym])
      apply (subst floor_add)
      apply simp
    done

    lemma ceiling_add_number_of [simp]: "ceiling (x + number_of n) =
        ceiling x + number_of n"
      apply (subst ceiling_add [THEN sym])
      apply simp
    done

    lemma ceiling_add_one [simp]: "ceiling (x + 1) = ceiling x + 1"
      apply (subst ceiling_add [THEN sym])
      apply simp
    done

    lemma ceiling_subtract [simp]: "ceiling (x - real a) = ceiling x - a"
      apply (subst diff_minus)+
      apply (subst real_of_int_minus [THEN sym])
      apply (rule ceiling_add)
    done

    lemma ceiling_subtract_number_of [simp]: "ceiling (x - number_of n) =
        ceiling x - number_of n"
      apply (subst ceiling_subtract [THEN sym])
      apply simp
    done

    lemma ceiling_subtract_one [simp]: "ceiling (x - 1) = ceiling x - 1"
      apply (subst ceiling_subtract [THEN sym])
      apply simp
    done

    subsection {* Versions for the natural numbers *}

    constdefs
      natfloor :: "real => nat"
      "natfloor x == nat(floor x)"
      natceiling :: "real => nat"
      "natceiling x == nat(ceiling x)"

    lemma natfloor_zero [simp]: "natfloor 0 = 0"
      by (unfold natfloor_def, simp)

    lemma natfloor_one [simp]: "natfloor 1 = 1"
      by (unfold natfloor_def, simp)

    lemma zero_le_natfloor [simp]: "0 <= natfloor x"
      by (unfold natfloor_def, simp)

    lemma natfloor_number_of_eq [simp]: "natfloor (number_of n) = number_of n"
      by (unfold natfloor_def, simp)

    lemma natfloor_real_of_nat [simp]: "natfloor(real n) = n"
      by (unfold natfloor_def, simp)

    lemma real_natfloor_le: "0 <= x ==> real(natfloor x) <= x"
      by (unfold natfloor_def, simp)

    lemma natfloor_neg: "x <= 0 ==> natfloor x = 0"
      apply (unfold natfloor_def)
      apply (subgoal_tac "floor x <= floor 0")
      apply simp
      apply (erule floor_mono2)
    done

    lemma natfloor_mono: "x <= y ==> natfloor x <= natfloor y"
      apply (case_tac "0 <= x")
      apply (subst natfloor_def)+
      apply (subst nat_le_eq_zle)
      apply force
      apply (erule floor_mono2)
      apply (subst natfloor_neg)
      apply simp
      apply simp
    done

    lemma le_natfloor: "real x <= a ==> x <= natfloor a"
      apply (unfold natfloor_def)
      apply (subst nat_int [THEN sym])
      apply (subst nat_le_eq_zle)
      apply simp
      apply (rule le_floor)
      apply simp
    done

    lemma le_natfloor_eq: "0 <= x ==> (a <= natfloor x) = (real a <= x)"
      apply (rule iffI)
      apply (rule order_trans)
      prefer 2
      apply (erule real_natfloor_le)
      apply (subst real_of_nat_le_iff)
      apply assumption
      apply (erule le_natfloor)
    done

    lemma le_natfloor_eq_number_of [simp]:
        "~ neg((number_of n)::int) ==> 0 <= x ==>
          (number_of n <= natfloor x) = (number_of n <= x)"
      apply (subst le_natfloor_eq, assumption)
      apply simp
    done

    lemma le_natfloor_eq_one [simp]: "(1 <= natfloor x) = (1 <= x)"
      apply (case_tac "0 <= x")
      apply (subst le_natfloor_eq, assumption, simp)
      apply (rule iffI)
      apply (subgoal_tac "natfloor x <= natfloor 0")
      apply simp
      apply (rule natfloor_mono)
      apply simp
      apply simp
    done

    lemma natfloor_eq: "real n <= x ==> x < real n + 1 ==> natfloor x = n"
      apply (unfold natfloor_def)
      apply (subst nat_int [THEN sym]);back;
      apply (subst eq_nat_nat_iff)
      apply simp
      apply simp
      apply (rule floor_eq2)
      apply auto
    done

    lemma real_natfloor_add_one_gt: "x < real(natfloor x) + 1"
      apply (case_tac "0 <= x")
      apply (unfold natfloor_def)
      apply simp
      apply simp_all
    done

    lemma real_natfloor_gt_diff_one: "x - 1 < real(natfloor x)"
      apply (simp add: compare_rls)
      apply (rule real_natfloor_add_one_gt)
    done

    lemma ge_natfloor_plus_one_imp_gt: "natfloor z + 1 <= n ==> z < real n"
      apply (subgoal_tac "z < real(natfloor z) + 1")
      apply arith
      apply (rule real_natfloor_add_one_gt)
    done

    lemma natfloor_add [simp]: "0 <= x ==> natfloor (x + real a) = natfloor x + a"
      apply (unfold natfloor_def)
      apply (subgoal_tac "real a = real (int a)")
      apply (erule ssubst)
      apply (simp add: nat_add_distrib)
      apply simp
    done

    lemma natfloor_add_number_of [simp]:
        "~neg ((number_of n)::int) ==> 0 <= x ==>
          natfloor (x + number_of n) = natfloor x + number_of n"
      apply (subst natfloor_add [THEN sym])
      apply simp_all
    done

    lemma natfloor_add_one: "0 <= x ==> natfloor(x + 1) = natfloor x + 1"
      apply (subst natfloor_add [THEN sym])
      apply assumption
      apply simp
    done

    lemma natfloor_subtract [simp]: "real a <= x ==>
        natfloor(x - real a) = natfloor x - a"
      apply (unfold natfloor_def)
      apply (subgoal_tac "real a = real (int a)")
      apply (erule ssubst)
      apply simp
      apply (subst nat_diff_distrib)
      apply simp
      apply (rule le_floor)
      apply simp_all
    done

    lemma natceiling_zero [simp]: "natceiling 0 = 0"
      by (unfold natceiling_def, simp)

    lemma natceiling_one [simp]: "natceiling 1 = 1"
      by (unfold natceiling_def, simp)

    lemma zero_le_natceiling [simp]: "0 <= natceiling x"
      by (unfold natceiling_def, simp)

    lemma natceiling_number_of_eq [simp]: "natceiling (number_of n) = number_of n"
      by (unfold natceiling_def, simp)

    lemma natceiling_real_of_nat [simp]: "natceiling(real n) = n"
      by (unfold natceiling_def, simp)

    lemma real_natceiling_ge: "x <= real(natceiling x)"
      apply (unfold natceiling_def)
      apply (case_tac "x < 0")
      apply simp
      apply (subst real_nat_eq_real)
      apply (subgoal_tac "ceiling 0 <= ceiling x")
      apply simp
      apply (rule ceiling_mono2)
      apply simp
      apply simp
    done

    lemma natceiling_neg: "x <= 0 ==> natceiling x = 0"
      apply (unfold natceiling_def)
      apply simp
    done

    lemma natceiling_mono: "x <= y ==> natceiling x <= natceiling y"
      apply (case_tac "0 <= x")
      apply (subst natceiling_def)+
      apply (subst nat_le_eq_zle)
      apply (rule disjI2)
      apply (subgoal_tac "real (0::int) <= real(ceiling y)")
      apply simp
      apply (rule order_trans)
      apply simp
      apply (erule order_trans)
      apply simp
      apply (erule ceiling_mono2)
      apply (subst natceiling_neg)
      apply simp_all
    done

    lemma natceiling_le: "x <= real a ==> natceiling x <= a"
      apply (unfold natceiling_def)
      apply (case_tac "x < 0")
      apply simp
      apply (subst nat_int [THEN sym]);back;
      apply (subst nat_le_eq_zle)
      apply simp
      apply (rule ceiling_le)
      apply simp
    done

    lemma natceiling_le_eq: "0 <= x ==> (natceiling x <= a) = (x <= real a)"
      apply (rule iffI)
      apply (rule order_trans)
      apply (rule real_natceiling_ge)
      apply (subst real_of_nat_le_iff)
      apply assumption
      apply (erule natceiling_le)
    done

    lemma natceiling_le_eq_number_of [simp]:
        "~ neg((number_of n)::int) ==> 0 <= x ==>
          (natceiling x <= number_of n) = (x <= number_of n)"
      apply (subst natceiling_le_eq, assumption)
      apply simp
    done

    lemma natceiling_le_eq_one: "(natceiling x <= 1) = (x <= 1)"
      apply (case_tac "0 <= x")
      apply (subst natceiling_le_eq)
      apply assumption
      apply simp
      apply (subst natceiling_neg)
      apply simp
      apply simp
    done

    lemma natceiling_eq: "real n < x ==> x <= real n + 1 ==> natceiling x = n + 1"
      apply (unfold natceiling_def)
      apply (subst nat_int [THEN sym]);back;
      apply (subgoal_tac "nat(int n) + 1 = nat(int n + 1)")
      apply (erule ssubst)
      apply (subst eq_nat_nat_iff)
      apply (subgoal_tac "ceiling 0 <= ceiling x")
      apply simp
      apply (rule ceiling_mono2)
      apply force
      apply force
      apply (rule ceiling_eq2)
      apply (simp, simp)
      apply (subst nat_add_distrib)
      apply auto
    done

    lemma natceiling_add [simp]: "0 <= x ==>
        natceiling (x + real a) = natceiling x + a"
      apply (unfold natceiling_def)
      apply (subgoal_tac "real a = real (int a)")
      apply (erule ssubst)
      apply simp
      apply (subst nat_add_distrib)
      apply (subgoal_tac "0 = ceiling 0")
      apply (erule ssubst)
      apply (erule ceiling_mono2)
      apply simp_all
    done

    lemma natceiling_add_number_of [simp]:
        "~ neg ((number_of n)::int) ==> 0 <= x ==>
          natceiling (x + number_of n) = natceiling x + number_of n"
      apply (subst natceiling_add [THEN sym])
      apply simp_all
    done

    lemma natceiling_add_one: "0 <= x ==> natceiling(x + 1) = natceiling x + 1"
      apply (subst natceiling_add [THEN sym])
      apply assumption
      apply simp
    done

    lemma natceiling_subtract [simp]: "real a <= x ==>
        natceiling(x - real a) = natceiling x - a"
      apply (unfold natceiling_def)
      apply (subgoal_tac "real a = real (int a)")
      apply (erule ssubst)
      apply simp
      apply (subst nat_diff_distrib)
      apply simp
      apply (rule order_trans)
      prefer 2
      apply (rule ceiling_mono2)
      apply assumption
      apply simp_all
    done

    lemma natfloor_div_nat: "1 <= x ==> 0 < y ==>
      natfloor (x / real y) = natfloor x div y"
    proof -
      assume "1 <= (x::real)" and "0 < (y::nat)"
      have "natfloor x = (natfloor x) div y * y + (natfloor x) mod y"
        by simp
      then have a: "real(natfloor x) = real ((natfloor x) div y) * real y +
        real((natfloor x) mod y)"
        by (simp only: real_of_nat_add [THEN sym] real_of_nat_mult [THEN sym])
      have "x = real(natfloor x) + (x - real(natfloor x))"
        by simp
      then have "x = real ((natfloor x) div y) * real y +
          real((natfloor x) mod y) + (x - real(natfloor x))"
        by (simp add: a)
      then have "x / real y = ... / real y"
        by simp
      also have "... = real((natfloor x) div y) + real((natfloor x) mod y) /
        real y + (x - real(natfloor x)) / real y"
        by (auto simp add: ring_distrib ring_eq_simps add_divide_distrib
          diff_divide_distrib prems)
      finally have "natfloor (x / real y) = natfloor(...)" by simp
      also have "... = natfloor(real((natfloor x) mod y) /
        real y + (x - real(natfloor x)) / real y + real((natfloor x) div y))"
        by (simp add: add_ac)
      also have "... = natfloor(real((natfloor x) mod y) /
        real y + (x - real(natfloor x)) / real y) + (natfloor x) div y"
        apply (rule natfloor_add)
        apply (rule add_nonneg_nonneg)
        apply (rule divide_nonneg_pos)
        apply simp
        apply (simp add: prems)
        apply (rule divide_nonneg_pos)
        apply (simp add: compare_rls)
        apply (rule real_natfloor_le)
        apply (insert prems, auto)
        done
      also have "natfloor(real((natfloor x) mod y) /
        real y + (x - real(natfloor x)) / real y) = 0"
        apply (rule natfloor_eq)
        apply simp
        apply (rule add_nonneg_nonneg)
        apply (rule divide_nonneg_pos)
        apply force
        apply (force simp add: prems)
        apply (rule divide_nonneg_pos)
        apply (simp add: compare_rls)
        apply (rule real_natfloor_le)
        apply (auto simp add: prems)
        apply (insert prems, arith)
        apply (simp add: add_divide_distrib [THEN sym])
        apply (subgoal_tac "real y = real y - 1 + 1")
        apply (erule ssubst)
        apply (rule add_le_less_mono)
        apply (simp add: compare_rls)
        apply (subgoal_tac "real(natfloor x mod y) + 1 =
          real(natfloor x mod y + 1)")
        apply (erule ssubst)
        apply (subst real_of_nat_le_iff)
        apply (subgoal_tac "natfloor x mod y < y")
        apply arith
        apply (rule mod_less_divisor)
        apply assumption
        apply auto
        apply (simp add: compare_rls)
        apply (subst add_commute)
        apply (rule real_natfloor_add_one_gt)
        done
      finally show ?thesis
        by simp
    qed

    ML
    {*
    val number_of_less_real_of_int_iff = thm "number_of_less_real_of_int_iff";
    val number_of_less_real_of_int_iff2 = thm "number_of_less_real_of_int_iff2";
    val number_of_le_real_of_int_iff = thm "number_of_le_real_of_int_iff";
    val number_of_le_real_of_int_iff2 = thm "number_of_le_real_of_int_iff2";
    val floor_zero = thm "floor_zero";
    val floor_real_of_nat_zero = thm "floor_real_of_nat_zero";
    val floor_real_of_nat = thm "floor_real_of_nat";
    val floor_minus_real_of_nat = thm "floor_minus_real_of_nat";
    val floor_real_of_int = thm "floor_real_of_int";
    val floor_minus_real_of_int = thm "floor_minus_real_of_int";
    val reals_Archimedean6 = thm "reals_Archimedean6";
    val reals_Archimedean6a = thm "reals_Archimedean6a";
    val reals_Archimedean_6b_int = thm "reals_Archimedean_6b_int";
    val reals_Archimedean_6c_int = thm "reals_Archimedean_6c_int";
    val real_lb_ub_int = thm "real_lb_ub_int";
    val lemma_floor = thm "lemma_floor";
    val real_of_int_floor_le = thm "real_of_int_floor_le";
    (*val floor_le = thm "floor_le";
    val floor_le2 = thm "floor_le2";
    *)
    val lemma_floor2 = thm "lemma_floor2";
    val real_of_int_floor_cancel = thm "real_of_int_floor_cancel";
    val floor_eq = thm "floor_eq";
    val floor_eq2 = thm "floor_eq2";
    val floor_eq3 = thm "floor_eq3";
    val floor_eq4 = thm "floor_eq4";
    val floor_number_of_eq = thm "floor_number_of_eq";
    val real_of_int_floor_ge_diff_one = thm "real_of_int_floor_ge_diff_one";
    val real_of_int_floor_add_one_ge = thm "real_of_int_floor_add_one_ge";
    val ceiling_zero = thm "ceiling_zero";
    val ceiling_real_of_nat = thm "ceiling_real_of_nat";
    val ceiling_real_of_nat_zero = thm "ceiling_real_of_nat_zero";
    val ceiling_floor = thm "ceiling_floor";
    val floor_ceiling = thm "floor_ceiling";
    val real_of_int_ceiling_ge = thm "real_of_int_ceiling_ge";
    (*
    val ceiling_le = thm "ceiling_le";
    val ceiling_le2 = thm "ceiling_le2";
    *)
    val real_of_int_ceiling_cancel = thm "real_of_int_ceiling_cancel";
    val ceiling_eq = thm "ceiling_eq";
    val ceiling_eq2 = thm "ceiling_eq2";
    val ceiling_eq3 = thm "ceiling_eq3";
    val ceiling_real_of_int = thm "ceiling_real_of_int";
    val ceiling_number_of_eq = thm "ceiling_number_of_eq";
    val real_of_int_ceiling_diff_one_le = thm "real_of_int_ceiling_diff_one_le";
    val real_of_int_ceiling_le_add_one = thm "real_of_int_ceiling_le_add_one";
    *}

    end

lemma real_sum_of_halves:

      x / 2 + x / 2 = x

### Completeness of Positive Reals

lemma posreal_complete:

      [| ∀x∈P. 0 < x; ∃x. x ∈ P; ∃y. ∀x∈P. x < y |]
      ==> ∃S. ∀y. (∃x∈P. y < x) = (y < S)

lemma real_isLub_unique:

      [| isLub R S x; isLub R S y |] ==> x = y

lemma posreals_complete:

      [| ∀x∈S. 0 < x; ∃x. x ∈ S; ∃u. isUb UNIV S u |] ==> ∃t. isLub UNIV S t

lemma reals_complete:

      [| ∃X. X ∈ S; ∃Y. isUb UNIV S Y |] ==> ∃t. isLub UNIV S t

### The Archimedean Property of the Reals

theorem reals_Archimedean:

      0 < x ==> ∃n. inverse (real (Suc n)) < x

lemma reals_Archimedean2:

      ∃n. x < real n

lemma reals_Archimedean3:

      0 < x ==> ∀y. ∃n. y < real n * x

lemma reals_Archimedean6:

      0 ≤ r ==> ∃n. real (n - 1) ≤ r ∧ r < real n

lemma reals_Archimedean6a:

      0 ≤ r ==> ∃n. real n ≤ r ∧ r < real (Suc n)

lemma reals_Archimedean_6b_int:

      0 ≤ r ==> ∃n. real n ≤ r ∧ r < real (n + 1)

lemma reals_Archimedean_6c_int:

      r < 0 ==> ∃n. real n ≤ r ∧ r < real (n + 1)

### Floor and Ceiling Functions from the Reals to the Integers

lemma number_of_less_real_of_int_iff:

      (number_of n < real m) = (number_of n < m)

lemma number_of_less_real_of_int_iff2:

      (real m < number_of n) = (m < number_of n)

lemma number_of_le_real_of_int_iff:

      (number_of n ≤ real m) = (number_of n ≤ m)

lemma number_of_le_real_of_int_iff2:

      (real m ≤ number_of n) = (m ≤ number_of n)

lemma floor_zero:

      ⌊0⌋ = 0

lemma floor_real_of_nat_zero:

      ⌊real 0⌋ = 0

lemma floor_real_of_nat:

      ⌊real n⌋ = int n

lemma floor_minus_real_of_nat:

      ⌊- real n⌋ = - int n

lemma floor_real_of_int:

      ⌊real n⌋ = n

lemma floor_minus_real_of_int:

      ⌊- real n⌋ = - n

lemma real_lb_ub_int:

      ∃n. real n ≤ r ∧ r < real (n + 1)

lemma lemma_floor:

      [| real m ≤ r; r < real n + 1 |] ==> m ≤ n

lemma real_of_int_floor_le:

      real ⌊r⌋ ≤ r

lemma floor_mono:

      x < y ==> ⌊x⌋ ≤ ⌊y⌋

lemma floor_mono2:

      x ≤ y ==> ⌊x⌋ ≤ ⌊y⌋

lemma lemma_floor2:

      real n < real x + 1 ==> n ≤ x

lemma real_of_int_floor_cancel:

      (real ⌊x⌋ = x) = (∃n. x = real n)

lemma floor_eq:

      [| real n < x; x < real n + 1 |] ==> ⌊x⌋ = n

lemma floor_eq2:

      [| real n ≤ x; x < real n + 1 |] ==> ⌊x⌋ = n

lemma floor_eq3:

      [| real n < x; x < real (Suc n) |] ==> nat ⌊x⌋ = n

lemma floor_eq4:

      [| real n ≤ x; x < real (Suc n) |] ==> nat ⌊x⌋ = n

lemma floor_number_of_eq:

      ⌊number_of n⌋ = number_of n

lemma floor_one:

      ⌊1⌋ = 1

lemma real_of_int_floor_ge_diff_one:

      r - 1 ≤ real ⌊r⌋

lemma real_of_int_floor_gt_diff_one:

      r - 1 < real ⌊r⌋

lemma real_of_int_floor_add_one_ge:

      r ≤ real ⌊r⌋ + 1

lemma real_of_int_floor_add_one_gt:

      r < real ⌊r⌋ + 1

lemma le_floor:

      real a ≤ x ==> a ≤ ⌊x⌋

lemma real_le_floor:

      a ≤ ⌊x⌋ ==> real a ≤ x

lemma le_floor_eq:

      (a ≤ ⌊x⌋) = (real a ≤ x)

lemma le_floor_eq_number_of:

      (number_of n ≤ ⌊x⌋) = (number_of n ≤ x)

lemma le_floor_eq_zero:

      (0 ≤ ⌊x⌋) = (0 ≤ x)

lemma le_floor_eq_one:

      (1 ≤ ⌊x⌋) = (1 ≤ x)

lemma floor_less_eq:

      (⌊x⌋ < a) = (x < real a)

lemma floor_less_eq_number_of:

      (⌊x⌋ < number_of n) = (x < number_of n)

lemma floor_less_eq_zero:

      (⌊x⌋ < 0) = (x < 0)

lemma floor_less_eq_one:

      (⌊x⌋ < 1) = (x < 1)

lemma less_floor_eq:

      (a < ⌊x⌋) = (real a + 1 ≤ x)

lemma less_floor_eq_number_of:

      (number_of n < ⌊x⌋) = (number_of n + 1 ≤ x)

lemma less_floor_eq_zero:

      (0 < ⌊x⌋) = (1 ≤ x)

lemma less_floor_eq_one:

      (1 < ⌊x⌋) = (2 ≤ x)

lemma floor_le_eq:

      (⌊x⌋ ≤ a) = (x < real a + 1)

lemma floor_le_eq_number_of:

      (⌊x⌋ ≤ number_of n) = (x < number_of n + 1)

lemma floor_le_eq_zero:

      (⌊x⌋ ≤ 0) = (x < 1)

lemma floor_le_eq_one:

      (⌊x⌋ ≤ 1) = (x < 2)

lemma floor_add:

      ⌊x + real a⌋ = ⌊x⌋ + a

lemma floor_add_number_of:

      ⌊x + number_of n⌋ = ⌊x⌋ + number_of n

lemma floor_add_one:

      ⌊x + 1⌋ = ⌊x⌋ + 1

lemma floor_subtract:

      ⌊x - real a⌋ = ⌊x⌋ - a

lemma floor_subtract_number_of:

      ⌊x - number_of n⌋ = ⌊x⌋ - number_of n

lemma floor_subtract_one:

      ⌊x - 1⌋ = ⌊x⌋ - 1

lemma ceiling_zero:

      ⌈0⌉ = 0

lemma ceiling_real_of_nat:

      ⌈real n⌉ = int n

lemma ceiling_real_of_nat_zero:

      ⌈real 0⌉ = 0

lemma ceiling_floor:

      ⌈real ⌊r⌋⌉ = ⌊r⌋

lemma floor_ceiling:

      ⌊real ⌈r⌉⌋ = ⌈r⌉

lemma real_of_int_ceiling_ge:

      r ≤ real ⌈r⌉

lemma ceiling_mono:

      x < y ==> ⌈x⌉ ≤ ⌈y⌉

lemma ceiling_mono2:

      x ≤ y ==> ⌈x⌉ ≤ ⌈y⌉

lemma real_of_int_ceiling_cancel:

      (real ⌈x⌉ = x) = (∃n. x = real n)

lemma ceiling_eq:

      [| real n < x; x < real n + 1 |] ==> ⌈x⌉ = n + 1

lemma ceiling_eq2:

      [| real n < x; x ≤ real n + 1 |] ==> ⌈x⌉ = n + 1

lemma ceiling_eq3:

      [| real n - 1 < x; x ≤ real n |] ==> ⌈x⌉ = n

lemma ceiling_real_of_int:

      ⌈real n⌉ = n

lemma ceiling_number_of_eq:

      ⌈number_of n⌉ = number_of n

lemma ceiling_one:

      ⌈1⌉ = 1

lemma real_of_int_ceiling_diff_one_le:

      real ⌈r⌉ - 1 ≤ r

lemma real_of_int_ceiling_le_add_one:

      real ⌈r⌉ ≤ r + 1

lemma ceiling_le:

      x ≤ real a ==> ⌈x⌉ ≤ a

lemma ceiling_le_real:

      ⌈x⌉ ≤ a ==> x ≤ real a

lemma ceiling_le_eq:

      (⌈x⌉ ≤ a) = (x ≤ real a)

lemma ceiling_le_eq_number_of:

      (⌈x⌉ ≤ number_of n) = (x ≤ number_of n)

lemma ceiling_le_zero_eq:

      (⌈x⌉ ≤ 0) = (x ≤ 0)

lemma ceiling_le_eq_one:

      (⌈x⌉ ≤ 1) = (x ≤ 1)

lemma less_ceiling_eq:

      (a < ⌈x⌉) = (real a < x)

lemma less_ceiling_eq_number_of:

      (number_of n < ⌈x⌉) = (number_of n < x)

lemma less_ceiling_eq_zero:

      (0 < ⌈x⌉) = (0 < x)

lemma less_ceiling_eq_one:

      (1 < ⌈x⌉) = (1 < x)

lemma ceiling_less_eq:

      (⌈x⌉ < a) = (x ≤ real a - 1)

lemma ceiling_less_eq_number_of:

      (⌈x⌉ < number_of n) = (x ≤ number_of n - 1)

lemma ceiling_less_eq_zero:

      (⌈x⌉ < 0) = (x ≤ -1)

lemma ceiling_less_eq_one:

      (⌈x⌉ < 1) = (x ≤ 0)

lemma le_ceiling_eq:

      (a ≤ ⌈x⌉) = (real a - 1 < x)

lemma le_ceiling_eq_number_of:

      (number_of n ≤ ⌈x⌉) = (number_of n - 1 < x)

lemma le_ceiling_eq_zero:

      (0 ≤ ⌈x⌉) = (-1 < x)

lemma le_ceiling_eq_one:

      (1 ≤ ⌈x⌉) = (0 < x)

lemma ceiling_add:

      ⌈x + real a⌉ = ⌈x⌉ + a

lemma ceiling_add_number_of:

      ⌈x + number_of n⌉ = ⌈x⌉ + number_of n

lemma ceiling_add_one:

      ⌈x + 1⌉ = ⌈x⌉ + 1

lemma ceiling_subtract:

      ⌈x - real a⌉ = ⌈x⌉ - a

lemma ceiling_subtract_number_of:

      ⌈x - number_of n⌉ = ⌈x⌉ - number_of n

lemma ceiling_subtract_one:

      ⌈x - 1⌉ = ⌈x⌉ - 1

### Versions for the natural numbers

lemma natfloor_zero:

      natfloor 0 = 0

lemma natfloor_one:

      natfloor 1 = 1

lemma zero_le_natfloor:

      0 ≤ natfloor x

lemma natfloor_number_of_eq:

      natfloor (number_of n) = number_of n

lemma natfloor_real_of_nat:

      natfloor (real n) = n

lemma real_natfloor_le:

      0 ≤ x ==> real (natfloor x) ≤ x

lemma natfloor_neg:

      x ≤ 0 ==> natfloor x = 0

lemma natfloor_mono:

      x ≤ y ==> natfloor x ≤ natfloor y

lemma le_natfloor:

      real x ≤ a ==> x ≤ natfloor a

lemma le_natfloor_eq:

      0 ≤ x ==> (a ≤ natfloor x) = (real a ≤ x)

lemma le_natfloor_eq_number_of:

      [| ¬ neg (number_of n); 0 ≤ x |]
      ==> (number_of n ≤ natfloor x) = (number_of n ≤ x)

lemma le_natfloor_eq_one:

      (1 ≤ natfloor x) = (1 ≤ x)

lemma natfloor_eq:

      [| real n ≤ x; x < real n + 1 |] ==> natfloor x = n

lemma real_natfloor_add_one_gt:

      x < real (natfloor x) + 1

lemma real_natfloor_gt_diff_one:

      x - 1 < real (natfloor x)

lemma ge_natfloor_plus_one_imp_gt:

      natfloor z + 1 ≤ n ==> z < real n

lemma natfloor_add:

      0 ≤ x ==> natfloor (x + real a) = natfloor x + a

lemma natfloor_add_number_of:

      [| ¬ neg (number_of n); 0 ≤ x |]
      ==> natfloor (x + number_of n) = natfloor x + number_of n

lemma natfloor_add_one:

      0 ≤ x ==> natfloor (x + 1) = natfloor x + 1

lemma natfloor_subtract:

      real a ≤ x ==> natfloor (x - real a) = natfloor x - a

lemma natceiling_zero:

      natceiling 0 = 0

lemma natceiling_one:

      natceiling 1 = 1

lemma zero_le_natceiling:

      0 ≤ natceiling x

lemma natceiling_number_of_eq:

      natceiling (number_of n) = number_of n

lemma natceiling_real_of_nat:

      natceiling (real n) = n

lemma real_natceiling_ge:

      x ≤ real (natceiling x)

lemma natceiling_neg:

      x ≤ 0 ==> natceiling x = 0

lemma natceiling_mono:

      x ≤ y ==> natceiling x ≤ natceiling y

lemma natceiling_le:

      x ≤ real a ==> natceiling x ≤ a

lemma natceiling_le_eq:

      0 ≤ x ==> (natceiling x ≤ a) = (x ≤ real a)

lemma natceiling_le_eq_number_of:

      [| ¬ neg (number_of n); 0 ≤ x |]
      ==> (natceiling x ≤ number_of n) = (x ≤ number_of n)

lemma natceiling_le_eq_one:

      (natceiling x ≤ 1) = (x ≤ 1)

lemma natceiling_eq:

      [| real n < x; x ≤ real n + 1 |] ==> natceiling x = n + 1

lemma natceiling_add:

      0 ≤ x ==> natceiling (x + real a) = natceiling x + a

lemma natceiling_add_number_of:

      [| ¬ neg (number_of n); 0 ≤ x |]
      ==> natceiling (x + number_of n) = natceiling x + number_of n

lemma natceiling_add_one:

      0 ≤ x ==> natceiling (x + 1) = natceiling x + 1

lemma natceiling_subtract:

      real a ≤ x ==> natceiling (x - real a) = natceiling x - a

lemma natfloor_div_nat:

      [| 1 ≤ x; 0 < y |] ==> natfloor (x / real y) = natfloor x div y