src/HOL/Real/RealDef.thy
author paulson
Tue Oct 05 15:30:50 2004 +0200 (2004-10-05)
changeset 15229 1eb23f805c06
parent 15169 2b5da07a0b89
child 15542 ee6cd48cf840
permissions -rw-r--r--
new simprules for abs and for things like a/b<1
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(*  Title       : Real/RealDef.thy
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    ID          : $Id$
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    Author      : Jacques D. Fleuriot
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    Copyright   : 1998  University of Cambridge
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    Conversion to Isar and new proofs by Lawrence C Paulson, 2003/4
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*)
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header{*Defining the Reals from the Positive Reals*}
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theory RealDef
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imports PReal
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files ("real_arith.ML")
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begin
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constdefs
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  realrel   ::  "((preal * preal) * (preal * preal)) set"
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  "realrel == {p. \<exists>x1 y1 x2 y2. p = ((x1,y1),(x2,y2)) & x1+y2 = x2+y1}"
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typedef (Real)  real = "UNIV//realrel"
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  by (auto simp add: quotient_def)
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instance real :: "{ord, zero, one, plus, times, minus, inverse}" ..
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constdefs
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  (** these don't use the overloaded "real" function: users don't see them **)
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  real_of_preal :: "preal => real"
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  "real_of_preal m     ==
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           Abs_Real(realrel``{(m + preal_of_rat 1, preal_of_rat 1)})"
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consts
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   (*Overloaded constant denoting the Real subset of enclosing
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     types such as hypreal and complex*)
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   Reals :: "'a set"
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   (*overloaded constant for injecting other types into "real"*)
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   real :: "'a => real"
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syntax (xsymbols)
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  Reals     :: "'a set"                   ("\<real>")
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defs (overloaded)
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  real_zero_def:
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  "0 == Abs_Real(realrel``{(preal_of_rat 1, preal_of_rat 1)})"
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  real_one_def:
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  "1 == Abs_Real(realrel``
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               {(preal_of_rat 1 + preal_of_rat 1,
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		 preal_of_rat 1)})"
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  real_minus_def:
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  "- r ==  contents (\<Union>(x,y) \<in> Rep_Real(r). { Abs_Real(realrel``{(y,x)}) })"
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  real_add_def:
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   "z + w ==
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       contents (\<Union>(x,y) \<in> Rep_Real(z). \<Union>(u,v) \<in> Rep_Real(w).
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		 { Abs_Real(realrel``{(x+u, y+v)}) })"
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  real_diff_def:
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   "r - (s::real) == r + - s"
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  real_mult_def:
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    "z * w ==
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       contents (\<Union>(x,y) \<in> Rep_Real(z). \<Union>(u,v) \<in> Rep_Real(w).
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		 { Abs_Real(realrel``{(x*u + y*v, x*v + y*u)}) })"
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  real_inverse_def:
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  "inverse (R::real) == (SOME S. (R = 0 & S = 0) | S * R = 1)"
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  real_divide_def:
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  "R / (S::real) == R * inverse S"
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  real_le_def:
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   "z \<le> (w::real) == 
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    \<exists>x y u v. x+v \<le> u+y & (x,y) \<in> Rep_Real z & (u,v) \<in> Rep_Real w"
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  real_less_def: "(x < (y::real)) == (x \<le> y & x \<noteq> y)"
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  real_abs_def:  "abs (r::real) == (if 0 \<le> r then r else -r)"
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subsection{*Proving that realrel is an equivalence relation*}
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lemma preal_trans_lemma:
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  assumes "x + y1 = x1 + y"
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      and "x + y2 = x2 + y"
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  shows "x1 + y2 = x2 + (y1::preal)"
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proof -
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  have "(x1 + y2) + x = (x + y2) + x1" by (simp add: preal_add_ac) 
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  also have "... = (x2 + y) + x1"  by (simp add: prems)
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  also have "... = x2 + (x1 + y)"  by (simp add: preal_add_ac)
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  also have "... = x2 + (x + y1)"  by (simp add: prems)
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  also have "... = (x2 + y1) + x"  by (simp add: preal_add_ac)
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  finally have "(x1 + y2) + x = (x2 + y1) + x" .
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  thus ?thesis by (simp add: preal_add_right_cancel_iff) 
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qed
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lemma realrel_iff [simp]: "(((x1,y1),(x2,y2)) \<in> realrel) = (x1 + y2 = x2 + y1)"
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by (simp add: realrel_def)
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lemma equiv_realrel: "equiv UNIV realrel"
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apply (auto simp add: equiv_def refl_def sym_def trans_def realrel_def)
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apply (blast dest: preal_trans_lemma) 
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done
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text{*Reduces equality of equivalence classes to the @{term realrel} relation:
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  @{term "(realrel `` {x} = realrel `` {y}) = ((x,y) \<in> realrel)"} *}
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lemmas equiv_realrel_iff = 
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       eq_equiv_class_iff [OF equiv_realrel UNIV_I UNIV_I]
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declare equiv_realrel_iff [simp]
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lemma realrel_in_real [simp]: "realrel``{(x,y)}: Real"
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by (simp add: Real_def realrel_def quotient_def, blast)
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lemma inj_on_Abs_Real: "inj_on Abs_Real Real"
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apply (rule inj_on_inverseI)
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apply (erule Abs_Real_inverse)
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done
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declare inj_on_Abs_Real [THEN inj_on_iff, simp]
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declare Abs_Real_inverse [simp]
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text{*Case analysis on the representation of a real number as an equivalence
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      class of pairs of positive reals.*}
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lemma eq_Abs_Real [case_names Abs_Real, cases type: real]: 
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     "(!!x y. z = Abs_Real(realrel``{(x,y)}) ==> P) ==> P"
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apply (rule Rep_Real [of z, unfolded Real_def, THEN quotientE])
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apply (drule arg_cong [where f=Abs_Real])
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apply (auto simp add: Rep_Real_inverse)
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done
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subsection{*Congruence property for addition*}
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lemma real_add_congruent2_lemma:
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     "[|a + ba = aa + b; ab + bc = ac + bb|]
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      ==> a + ab + (ba + bc) = aa + ac + (b + (bb::preal))"
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apply (simp add: preal_add_assoc) 
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apply (rule preal_add_left_commute [of ab, THEN ssubst])
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apply (simp add: preal_add_assoc [symmetric])
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apply (simp add: preal_add_ac)
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done
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lemma real_add:
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     "Abs_Real (realrel``{(x,y)}) + Abs_Real (realrel``{(u,v)}) =
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      Abs_Real (realrel``{(x+u, y+v)})"
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proof -
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  have "(\<lambda>z w. (\<lambda>(x,y). (\<lambda>(u,v). {Abs_Real (realrel `` {(x+u, y+v)})}) w) z)
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        respects2 realrel"
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    by (simp add: congruent2_def, blast intro: real_add_congruent2_lemma) 
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  thus ?thesis
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    by (simp add: real_add_def UN_UN_split_split_eq
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                  UN_equiv_class2 [OF equiv_realrel equiv_realrel])
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qed
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lemma real_add_commute: "(z::real) + w = w + z"
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by (cases z, cases w, simp add: real_add preal_add_ac)
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lemma real_add_assoc: "((z1::real) + z2) + z3 = z1 + (z2 + z3)"
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by (cases z1, cases z2, cases z3, simp add: real_add preal_add_assoc)
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lemma real_add_zero_left: "(0::real) + z = z"
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by (cases z, simp add: real_add real_zero_def preal_add_ac)
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instance real :: comm_monoid_add
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  by (intro_classes,
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      (assumption | 
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       rule real_add_commute real_add_assoc real_add_zero_left)+)
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subsection{*Additive Inverse on real*}
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lemma real_minus: "- Abs_Real(realrel``{(x,y)}) = Abs_Real(realrel `` {(y,x)})"
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proof -
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  have "(\<lambda>(x,y). {Abs_Real (realrel``{(y,x)})}) respects realrel"
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    by (simp add: congruent_def preal_add_commute) 
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  thus ?thesis
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    by (simp add: real_minus_def UN_equiv_class [OF equiv_realrel])
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qed
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lemma real_add_minus_left: "(-z) + z = (0::real)"
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by (cases z, simp add: real_minus real_add real_zero_def preal_add_commute)
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subsection{*Congruence property for multiplication*}
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lemma real_mult_congruent2_lemma:
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     "!!(x1::preal). [| x1 + y2 = x2 + y1 |] ==>
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          x * x1 + y * y1 + (x * y2 + y * x2) =
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          x * x2 + y * y2 + (x * y1 + y * x1)"
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apply (simp add: preal_add_left_commute preal_add_assoc [symmetric])
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apply (simp add: preal_add_assoc preal_add_mult_distrib2 [symmetric])
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apply (simp add: preal_add_commute)
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done
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lemma real_mult_congruent2:
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    "(%p1 p2.
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        (%(x1,y1). (%(x2,y2). 
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          { Abs_Real (realrel``{(x1*x2 + y1*y2, x1*y2+y1*x2)}) }) p2) p1)
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     respects2 realrel"
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apply (rule congruent2_commuteI [OF equiv_realrel], clarify)
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apply (simp add: preal_mult_commute preal_add_commute)
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apply (auto simp add: real_mult_congruent2_lemma)
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done
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lemma real_mult:
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      "Abs_Real((realrel``{(x1,y1)})) * Abs_Real((realrel``{(x2,y2)})) =
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       Abs_Real(realrel `` {(x1*x2+y1*y2,x1*y2+y1*x2)})"
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by (simp add: real_mult_def UN_UN_split_split_eq
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         UN_equiv_class2 [OF equiv_realrel equiv_realrel real_mult_congruent2])
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lemma real_mult_commute: "(z::real) * w = w * z"
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by (cases z, cases w, simp add: real_mult preal_add_ac preal_mult_ac)
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lemma real_mult_assoc: "((z1::real) * z2) * z3 = z1 * (z2 * z3)"
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apply (cases z1, cases z2, cases z3)
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apply (simp add: real_mult preal_add_mult_distrib2 preal_add_ac preal_mult_ac)
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done
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lemma real_mult_1: "(1::real) * z = z"
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apply (cases z)
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apply (simp add: real_mult real_one_def preal_add_mult_distrib2
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                 preal_mult_1_right preal_mult_ac preal_add_ac)
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done
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lemma real_add_mult_distrib: "((z1::real) + z2) * w = (z1 * w) + (z2 * w)"
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apply (cases z1, cases z2, cases w)
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apply (simp add: real_add real_mult preal_add_mult_distrib2 
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                 preal_add_ac preal_mult_ac)
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done
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text{*one and zero are distinct*}
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lemma real_zero_not_eq_one: "0 \<noteq> (1::real)"
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proof -
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  have "preal_of_rat 1 < preal_of_rat 1 + preal_of_rat 1"
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    by (simp add: preal_self_less_add_left) 
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  thus ?thesis
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    by (simp add: real_zero_def real_one_def preal_add_right_cancel_iff)
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qed
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subsection{*existence of inverse*}
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lemma real_zero_iff: "Abs_Real (realrel `` {(x, x)}) = 0"
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by (simp add: real_zero_def preal_add_commute)
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text{*Instead of using an existential quantifier and constructing the inverse
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within the proof, we could define the inverse explicitly.*}
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lemma real_mult_inverse_left_ex: "x \<noteq> 0 ==> \<exists>y. y*x = (1::real)"
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apply (simp add: real_zero_def real_one_def, cases x)
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apply (cut_tac x = xa and y = y in linorder_less_linear)
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apply (auto dest!: less_add_left_Ex simp add: real_zero_iff)
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apply (rule_tac
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        x = "Abs_Real (realrel `` { (preal_of_rat 1, 
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                            inverse (D) + preal_of_rat 1)}) " 
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       in exI)
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apply (rule_tac [2]
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        x = "Abs_Real (realrel `` { (inverse (D) + preal_of_rat 1,
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                   preal_of_rat 1)})" 
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       in exI)
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apply (auto simp add: real_mult preal_mult_1_right
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              preal_add_mult_distrib2 preal_add_mult_distrib preal_mult_1
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              preal_mult_inverse_right preal_add_ac preal_mult_ac)
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done
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lemma real_mult_inverse_left: "x \<noteq> 0 ==> inverse(x)*x = (1::real)"
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apply (simp add: real_inverse_def)
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apply (frule real_mult_inverse_left_ex, safe)
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apply (rule someI2, auto)
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done
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subsection{*The Real Numbers form a Field*}
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instance real :: field
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proof
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  fix x y z :: real
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  show "- x + x = 0" by (rule real_add_minus_left)
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  show "x - y = x + (-y)" by (simp add: real_diff_def)
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  show "(x * y) * z = x * (y * z)" by (rule real_mult_assoc)
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  show "x * y = y * x" by (rule real_mult_commute)
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  show "1 * x = x" by (rule real_mult_1)
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  show "(x + y) * z = x * z + y * z" by (simp add: real_add_mult_distrib)
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  show "0 \<noteq> (1::real)" by (rule real_zero_not_eq_one)
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  show "x \<noteq> 0 ==> inverse x * x = 1" by (rule real_mult_inverse_left)
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  show "x / y = x * inverse y" by (simp add: real_divide_def)
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qed
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text{*Inverse of zero!  Useful to simplify certain equations*}
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lemma INVERSE_ZERO: "inverse 0 = (0::real)"
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by (simp add: real_inverse_def)
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instance real :: division_by_zero
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proof
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  show "inverse 0 = (0::real)" by (rule INVERSE_ZERO)
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qed
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(*Pull negations out*)
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declare minus_mult_right [symmetric, simp] 
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        minus_mult_left [symmetric, simp]
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lemma real_mult_1_right: "z * (1::real) = z"
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  by (rule OrderedGroup.mult_1_right)
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   316
paulson@14269
   317
paulson@14365
   318
subsection{*The @{text "\<le>"} Ordering*}
paulson@14269
   319
paulson@14365
   320
lemma real_le_refl: "w \<le> (w::real)"
paulson@14484
   321
by (cases w, force simp add: real_le_def)
paulson@14269
   322
paulson@14378
   323
text{*The arithmetic decision procedure is not set up for type preal.
paulson@14378
   324
  This lemma is currently unused, but it could simplify the proofs of the
paulson@14378
   325
  following two lemmas.*}
paulson@14378
   326
lemma preal_eq_le_imp_le:
paulson@14378
   327
  assumes eq: "a+b = c+d" and le: "c \<le> a"
paulson@14378
   328
  shows "b \<le> (d::preal)"
paulson@14378
   329
proof -
paulson@14378
   330
  have "c+d \<le> a+d" by (simp add: prems preal_cancels)
paulson@14378
   331
  hence "a+b \<le> a+d" by (simp add: prems)
paulson@14378
   332
  thus "b \<le> d" by (simp add: preal_cancels)
paulson@14378
   333
qed
paulson@14378
   334
paulson@14378
   335
lemma real_le_lemma:
paulson@14378
   336
  assumes l: "u1 + v2 \<le> u2 + v1"
paulson@14378
   337
      and "x1 + v1 = u1 + y1"
paulson@14378
   338
      and "x2 + v2 = u2 + y2"
paulson@14378
   339
  shows "x1 + y2 \<le> x2 + (y1::preal)"
paulson@14365
   340
proof -
paulson@14378
   341
  have "(x1+v1) + (u2+y2) = (u1+y1) + (x2+v2)" by (simp add: prems)
paulson@14378
   342
  hence "(x1+y2) + (u2+v1) = (x2+y1) + (u1+v2)" by (simp add: preal_add_ac)
paulson@14378
   343
  also have "... \<le> (x2+y1) + (u2+v1)"
paulson@14365
   344
         by (simp add: prems preal_add_le_cancel_left)
paulson@14378
   345
  finally show ?thesis by (simp add: preal_add_le_cancel_right)
paulson@14378
   346
qed						 
paulson@14378
   347
paulson@14378
   348
lemma real_le: 
paulson@14484
   349
     "(Abs_Real(realrel``{(x1,y1)}) \<le> Abs_Real(realrel``{(x2,y2)})) =  
paulson@14484
   350
      (x1 + y2 \<le> x2 + y1)"
paulson@14378
   351
apply (simp add: real_le_def) 
paulson@14387
   352
apply (auto intro: real_le_lemma)
paulson@14378
   353
done
paulson@14378
   354
paulson@14378
   355
lemma real_le_anti_sym: "[| z \<le> w; w \<le> z |] ==> z = (w::real)"
paulson@14497
   356
by (cases z, cases w, simp add: real_le order_antisym)
paulson@14378
   357
paulson@14378
   358
lemma real_trans_lemma:
paulson@14378
   359
  assumes "x + v \<le> u + y"
paulson@14378
   360
      and "u + v' \<le> u' + v"
paulson@14378
   361
      and "x2 + v2 = u2 + y2"
paulson@14378
   362
  shows "x + v' \<le> u' + (y::preal)"
paulson@14378
   363
proof -
paulson@14378
   364
  have "(x+v') + (u+v) = (x+v) + (u+v')" by (simp add: preal_add_ac)
paulson@14378
   365
  also have "... \<le> (u+y) + (u+v')" 
paulson@14378
   366
    by (simp add: preal_add_le_cancel_right prems) 
paulson@14378
   367
  also have "... \<le> (u+y) + (u'+v)" 
paulson@14378
   368
    by (simp add: preal_add_le_cancel_left prems) 
paulson@14378
   369
  also have "... = (u'+y) + (u+v)"  by (simp add: preal_add_ac)
paulson@14378
   370
  finally show ?thesis by (simp add: preal_add_le_cancel_right)
paulson@14365
   371
qed						 
paulson@14269
   372
paulson@14365
   373
lemma real_le_trans: "[| i \<le> j; j \<le> k |] ==> i \<le> (k::real)"
paulson@14484
   374
apply (cases i, cases j, cases k)
paulson@14484
   375
apply (simp add: real_le)
paulson@14378
   376
apply (blast intro: real_trans_lemma) 
paulson@14334
   377
done
paulson@14334
   378
paulson@14334
   379
(* Axiom 'order_less_le' of class 'order': *)
paulson@14334
   380
lemma real_less_le: "((w::real) < z) = (w \<le> z & w \<noteq> z)"
paulson@14365
   381
by (simp add: real_less_def)
paulson@14365
   382
paulson@14365
   383
instance real :: order
paulson@14365
   384
proof qed
paulson@14365
   385
 (assumption |
paulson@14365
   386
  rule real_le_refl real_le_trans real_le_anti_sym real_less_le)+
paulson@14365
   387
paulson@14378
   388
(* Axiom 'linorder_linear' of class 'linorder': *)
paulson@14378
   389
lemma real_le_linear: "(z::real) \<le> w | w \<le> z"
paulson@14484
   390
apply (cases z, cases w) 
paulson@14378
   391
apply (auto simp add: real_le real_zero_def preal_add_ac preal_cancels)
paulson@14334
   392
done
paulson@14334
   393
paulson@14334
   394
paulson@14334
   395
instance real :: linorder
paulson@14334
   396
  by (intro_classes, rule real_le_linear)
paulson@14334
   397
paulson@14334
   398
paulson@14378
   399
lemma real_le_eq_diff: "(x \<le> y) = (x-y \<le> (0::real))"
paulson@14484
   400
apply (cases x, cases y) 
paulson@14378
   401
apply (auto simp add: real_le real_zero_def real_diff_def real_add real_minus
paulson@14378
   402
                      preal_add_ac)
paulson@14378
   403
apply (simp_all add: preal_add_assoc [symmetric] preal_cancels)
paulson@14378
   404
done 
paulson@14378
   405
paulson@14484
   406
lemma real_add_left_mono: 
paulson@14484
   407
  assumes le: "x \<le> y" shows "z + x \<le> z + (y::real)"
paulson@14484
   408
proof -
paulson@14484
   409
  have "z + x - (z + y) = (z + -z) + (x - y)"
paulson@14484
   410
    by (simp add: diff_minus add_ac) 
paulson@14484
   411
  with le show ?thesis 
obua@14754
   412
    by (simp add: real_le_eq_diff[of x] real_le_eq_diff[of "z+x"] diff_minus)
paulson@14484
   413
qed
paulson@14334
   414
paulson@14365
   415
lemma real_sum_gt_zero_less: "(0 < S + (-W::real)) ==> (W < S)"
paulson@14365
   416
by (simp add: linorder_not_le [symmetric] real_le_eq_diff [of S] diff_minus)
paulson@14365
   417
paulson@14365
   418
lemma real_less_sum_gt_zero: "(W < S) ==> (0 < S + (-W::real))"
paulson@14365
   419
by (simp add: linorder_not_le [symmetric] real_le_eq_diff [of S] diff_minus)
paulson@14334
   420
paulson@14334
   421
lemma real_mult_order: "[| 0 < x; 0 < y |] ==> (0::real) < x * y"
paulson@14484
   422
apply (cases x, cases y)
paulson@14378
   423
apply (simp add: linorder_not_le [where 'a = real, symmetric] 
paulson@14378
   424
                 linorder_not_le [where 'a = preal] 
paulson@14378
   425
                  real_zero_def real_le real_mult)
paulson@14365
   426
  --{*Reduce to the (simpler) @{text "\<le>"} relation *}
paulson@14378
   427
apply (auto  dest!: less_add_left_Ex 
paulson@14365
   428
     simp add: preal_add_ac preal_mult_ac 
paulson@14378
   429
          preal_add_mult_distrib2 preal_cancels preal_self_less_add_right)
paulson@14334
   430
done
paulson@14334
   431
paulson@14334
   432
lemma real_mult_less_mono2: "[| (0::real) < z; x < y |] ==> z * x < z * y"
paulson@14334
   433
apply (rule real_sum_gt_zero_less)
paulson@14334
   434
apply (drule real_less_sum_gt_zero [of x y])
paulson@14334
   435
apply (drule real_mult_order, assumption)
paulson@14334
   436
apply (simp add: right_distrib)
paulson@14334
   437
done
paulson@14334
   438
paulson@14365
   439
text{*lemma for proving @{term "0<(1::real)"}*}
paulson@14365
   440
lemma real_zero_le_one: "0 \<le> (1::real)"
paulson@14387
   441
by (simp add: real_zero_def real_one_def real_le 
paulson@14378
   442
                 preal_self_less_add_left order_less_imp_le)
paulson@14334
   443
paulson@14378
   444
paulson@14334
   445
subsection{*The Reals Form an Ordered Field*}
paulson@14334
   446
paulson@14334
   447
instance real :: ordered_field
paulson@14334
   448
proof
paulson@14334
   449
  fix x y z :: real
paulson@14334
   450
  show "x \<le> y ==> z + x \<le> z + y" by (rule real_add_left_mono)
paulson@14334
   451
  show "x < y ==> 0 < z ==> z * x < z * y" by (simp add: real_mult_less_mono2)
paulson@14334
   452
  show "\<bar>x\<bar> = (if x < 0 then -x else x)"
paulson@14334
   453
    by (auto dest: order_le_less_trans simp add: real_abs_def linorder_not_le)
paulson@14334
   454
qed
paulson@14334
   455
paulson@14365
   456
paulson@14365
   457
paulson@14365
   458
text{*The function @{term real_of_preal} requires many proofs, but it seems
paulson@14365
   459
to be essential for proving completeness of the reals from that of the
paulson@14365
   460
positive reals.*}
paulson@14365
   461
paulson@14365
   462
lemma real_of_preal_add:
paulson@14365
   463
     "real_of_preal ((x::preal) + y) = real_of_preal x + real_of_preal y"
paulson@14365
   464
by (simp add: real_of_preal_def real_add preal_add_mult_distrib preal_mult_1 
paulson@14365
   465
              preal_add_ac)
paulson@14365
   466
paulson@14365
   467
lemma real_of_preal_mult:
paulson@14365
   468
     "real_of_preal ((x::preal) * y) = real_of_preal x* real_of_preal y"
paulson@14365
   469
by (simp add: real_of_preal_def real_mult preal_add_mult_distrib2
paulson@14365
   470
              preal_mult_1 preal_mult_1_right preal_add_ac preal_mult_ac)
paulson@14365
   471
paulson@14365
   472
paulson@14365
   473
text{*Gleason prop 9-4.4 p 127*}
paulson@14365
   474
lemma real_of_preal_trichotomy:
paulson@14365
   475
      "\<exists>m. (x::real) = real_of_preal m | x = 0 | x = -(real_of_preal m)"
paulson@14484
   476
apply (simp add: real_of_preal_def real_zero_def, cases x)
paulson@14365
   477
apply (auto simp add: real_minus preal_add_ac)
paulson@14365
   478
apply (cut_tac x = x and y = y in linorder_less_linear)
paulson@14365
   479
apply (auto dest!: less_add_left_Ex simp add: preal_add_assoc [symmetric])
paulson@14365
   480
apply (auto simp add: preal_add_commute)
paulson@14365
   481
done
paulson@14365
   482
paulson@14365
   483
lemma real_of_preal_leD:
paulson@14365
   484
      "real_of_preal m1 \<le> real_of_preal m2 ==> m1 \<le> m2"
paulson@14484
   485
by (simp add: real_of_preal_def real_le preal_cancels)
paulson@14365
   486
paulson@14365
   487
lemma real_of_preal_lessI: "m1 < m2 ==> real_of_preal m1 < real_of_preal m2"
paulson@14365
   488
by (auto simp add: real_of_preal_leD linorder_not_le [symmetric])
paulson@14365
   489
paulson@14365
   490
lemma real_of_preal_lessD:
paulson@14365
   491
      "real_of_preal m1 < real_of_preal m2 ==> m1 < m2"
paulson@14484
   492
by (simp add: real_of_preal_def real_le linorder_not_le [symmetric] 
paulson@14484
   493
              preal_cancels) 
paulson@14484
   494
paulson@14365
   495
paulson@14365
   496
lemma real_of_preal_less_iff [simp]:
paulson@14365
   497
     "(real_of_preal m1 < real_of_preal m2) = (m1 < m2)"
paulson@14365
   498
by (blast intro: real_of_preal_lessI real_of_preal_lessD)
paulson@14365
   499
paulson@14365
   500
lemma real_of_preal_le_iff:
paulson@14365
   501
     "(real_of_preal m1 \<le> real_of_preal m2) = (m1 \<le> m2)"
paulson@14365
   502
by (simp add: linorder_not_less [symmetric]) 
paulson@14365
   503
paulson@14365
   504
lemma real_of_preal_zero_less: "0 < real_of_preal m"
paulson@14365
   505
apply (auto simp add: real_zero_def real_of_preal_def real_less_def real_le_def
paulson@14365
   506
            preal_add_ac preal_cancels)
paulson@14365
   507
apply (simp_all add: preal_add_assoc [symmetric] preal_cancels)
paulson@14365
   508
apply (blast intro: preal_self_less_add_left order_less_imp_le)
paulson@14365
   509
apply (insert preal_not_eq_self [of "preal_of_rat 1" m]) 
paulson@14365
   510
apply (simp add: preal_add_ac) 
paulson@14365
   511
done
paulson@14365
   512
paulson@14365
   513
lemma real_of_preal_minus_less_zero: "- real_of_preal m < 0"
paulson@14365
   514
by (simp add: real_of_preal_zero_less)
paulson@14365
   515
paulson@14365
   516
lemma real_of_preal_not_minus_gt_zero: "~ 0 < - real_of_preal m"
paulson@14484
   517
proof -
paulson@14484
   518
  from real_of_preal_minus_less_zero
paulson@14484
   519
  show ?thesis by (blast dest: order_less_trans)
paulson@14484
   520
qed
paulson@14365
   521
paulson@14365
   522
paulson@14365
   523
subsection{*Theorems About the Ordering*}
paulson@14365
   524
paulson@14365
   525
text{*obsolete but used a lot*}
paulson@14365
   526
paulson@14365
   527
lemma real_not_refl2: "x < y ==> x \<noteq> (y::real)"
paulson@14365
   528
by blast 
paulson@14365
   529
paulson@14365
   530
lemma real_le_imp_less_or_eq: "!!(x::real). x \<le> y ==> x < y | x = y"
paulson@14365
   531
by (simp add: order_le_less)
paulson@14365
   532
paulson@14365
   533
lemma real_gt_zero_preal_Ex: "(0 < x) = (\<exists>y. x = real_of_preal y)"
paulson@14365
   534
apply (auto simp add: real_of_preal_zero_less)
paulson@14365
   535
apply (cut_tac x = x in real_of_preal_trichotomy)
paulson@14365
   536
apply (blast elim!: real_of_preal_not_minus_gt_zero [THEN notE])
paulson@14365
   537
done
paulson@14365
   538
paulson@14365
   539
lemma real_gt_preal_preal_Ex:
paulson@14365
   540
     "real_of_preal z < x ==> \<exists>y. x = real_of_preal y"
paulson@14365
   541
by (blast dest!: real_of_preal_zero_less [THEN order_less_trans]
paulson@14365
   542
             intro: real_gt_zero_preal_Ex [THEN iffD1])
paulson@14365
   543
paulson@14365
   544
lemma real_ge_preal_preal_Ex:
paulson@14365
   545
     "real_of_preal z \<le> x ==> \<exists>y. x = real_of_preal y"
paulson@14365
   546
by (blast dest: order_le_imp_less_or_eq real_gt_preal_preal_Ex)
paulson@14365
   547
paulson@14365
   548
lemma real_less_all_preal: "y \<le> 0 ==> \<forall>x. y < real_of_preal x"
paulson@14365
   549
by (auto elim: order_le_imp_less_or_eq [THEN disjE] 
paulson@14365
   550
            intro: real_of_preal_zero_less [THEN [2] order_less_trans] 
paulson@14365
   551
            simp add: real_of_preal_zero_less)
paulson@14365
   552
paulson@14365
   553
lemma real_less_all_real2: "~ 0 < y ==> \<forall>x. y < real_of_preal x"
paulson@14365
   554
by (blast intro!: real_less_all_preal linorder_not_less [THEN iffD1])
paulson@14365
   555
paulson@14334
   556
lemma real_add_less_le_mono: "[| w'<w; z'\<le>z |] ==> w' + z' < w + (z::real)"
obua@14738
   557
  by (rule OrderedGroup.add_less_le_mono)
paulson@14334
   558
paulson@14334
   559
lemma real_add_le_less_mono:
paulson@14334
   560
     "!!z z'::real. [| w'\<le>w; z'<z |] ==> w' + z' < w + z"
obua@14738
   561
  by (rule OrderedGroup.add_le_less_mono)
paulson@14334
   562
paulson@14334
   563
lemma real_le_square [simp]: "(0::real) \<le> x*x"
paulson@14334
   564
 by (rule Ring_and_Field.zero_le_square)
paulson@14334
   565
paulson@14334
   566
paulson@14334
   567
subsection{*More Lemmas*}
paulson@14334
   568
paulson@14334
   569
lemma real_mult_left_cancel: "(c::real) \<noteq> 0 ==> (c*a=c*b) = (a=b)"
paulson@14334
   570
by auto
paulson@14334
   571
paulson@14334
   572
lemma real_mult_right_cancel: "(c::real) \<noteq> 0 ==> (a*c=b*c) = (a=b)"
paulson@14334
   573
by auto
paulson@14334
   574
paulson@14334
   575
text{*The precondition could be weakened to @{term "0\<le>x"}*}
paulson@14334
   576
lemma real_mult_less_mono:
paulson@14334
   577
     "[| u<v;  x<y;  (0::real) < v;  0 < x |] ==> u*x < v* y"
paulson@14334
   578
 by (simp add: Ring_and_Field.mult_strict_mono order_less_imp_le)
paulson@14334
   579
paulson@14334
   580
lemma real_mult_less_iff1 [simp]: "(0::real) < z ==> (x*z < y*z) = (x < y)"
paulson@14334
   581
  by (force elim: order_less_asym
paulson@14334
   582
            simp add: Ring_and_Field.mult_less_cancel_right)
paulson@14334
   583
paulson@14334
   584
lemma real_mult_le_cancel_iff1 [simp]: "(0::real) < z ==> (x*z \<le> y*z) = (x\<le>y)"
paulson@14365
   585
apply (simp add: mult_le_cancel_right)
paulson@14365
   586
apply (blast intro: elim: order_less_asym) 
paulson@14365
   587
done
paulson@14334
   588
paulson@14334
   589
lemma real_mult_le_cancel_iff2 [simp]: "(0::real) < z ==> (z*x \<le> z*y) = (x\<le>y)"
paulson@14334
   590
  by (force elim: order_less_asym
paulson@14334
   591
            simp add: Ring_and_Field.mult_le_cancel_left)
paulson@14334
   592
paulson@14334
   593
text{*Only two uses?*}
paulson@14334
   594
lemma real_mult_less_mono':
paulson@14334
   595
     "[| x < y;  r1 < r2;  (0::real) \<le> r1;  0 \<le> x|] ==> r1 * x < r2 * y"
paulson@14334
   596
 by (rule Ring_and_Field.mult_strict_mono')
paulson@14334
   597
paulson@14334
   598
text{*FIXME: delete or at least combine the next two lemmas*}
paulson@14334
   599
lemma real_sum_squares_cancel: "x * x + y * y = 0 ==> x = (0::real)"
obua@14738
   600
apply (drule OrderedGroup.equals_zero_I [THEN sym])
paulson@14334
   601
apply (cut_tac x = y in real_le_square) 
paulson@14476
   602
apply (auto, drule order_antisym, auto)
paulson@14334
   603
done
paulson@14334
   604
paulson@14334
   605
lemma real_sum_squares_cancel2: "x * x + y * y = 0 ==> y = (0::real)"
paulson@14334
   606
apply (rule_tac y = x in real_sum_squares_cancel)
paulson@14476
   607
apply (simp add: add_commute)
paulson@14334
   608
done
paulson@14334
   609
paulson@14334
   610
lemma real_add_order: "[| 0 < x; 0 < y |] ==> (0::real) < x + y"
paulson@14365
   611
by (drule add_strict_mono [of concl: 0 0], assumption, simp)
paulson@14334
   612
paulson@14334
   613
lemma real_le_add_order: "[| 0 \<le> x; 0 \<le> y |] ==> (0::real) \<le> x + y"
paulson@14334
   614
apply (drule order_le_imp_less_or_eq)+
paulson@14334
   615
apply (auto intro: real_add_order order_less_imp_le)
paulson@14334
   616
done
paulson@14334
   617
paulson@14365
   618
lemma real_inverse_unique: "x*y = (1::real) ==> y = inverse x"
paulson@14365
   619
apply (case_tac "x \<noteq> 0")
paulson@14365
   620
apply (rule_tac c1 = x in real_mult_left_cancel [THEN iffD1], auto)
paulson@14365
   621
done
paulson@14334
   622
paulson@14365
   623
lemma real_inverse_gt_one: "[| (0::real) < x; x < 1 |] ==> 1 < inverse x"
paulson@14365
   624
by (auto dest: less_imp_inverse_less)
paulson@14334
   625
paulson@14365
   626
lemma real_mult_self_sum_ge_zero: "(0::real) \<le> x*x + y*y"
paulson@14365
   627
proof -
paulson@14365
   628
  have "0 + 0 \<le> x*x + y*y" by (blast intro: add_mono zero_le_square)
paulson@14365
   629
  thus ?thesis by simp
paulson@14365
   630
qed
paulson@14365
   631
paulson@14334
   632
paulson@14365
   633
subsection{*Embedding the Integers into the Reals*}
paulson@14365
   634
paulson@14378
   635
defs (overloaded)
paulson@14378
   636
  real_of_nat_def: "real z == of_nat z"
paulson@14378
   637
  real_of_int_def: "real z == of_int z"
paulson@14365
   638
paulson@14365
   639
lemma real_of_int_zero [simp]: "real (0::int) = 0"  
paulson@14378
   640
by (simp add: real_of_int_def) 
paulson@14365
   641
paulson@14365
   642
lemma real_of_one [simp]: "real (1::int) = (1::real)"
paulson@14378
   643
by (simp add: real_of_int_def) 
paulson@14334
   644
paulson@14365
   645
lemma real_of_int_add: "real (x::int) + real y = real (x + y)"
paulson@14378
   646
by (simp add: real_of_int_def) 
paulson@14365
   647
declare real_of_int_add [symmetric, simp]
paulson@14365
   648
paulson@14365
   649
lemma real_of_int_minus: "-real (x::int) = real (-x)"
paulson@14378
   650
by (simp add: real_of_int_def) 
paulson@14365
   651
declare real_of_int_minus [symmetric, simp]
paulson@14365
   652
paulson@14365
   653
lemma real_of_int_diff: "real (x::int) - real y = real (x - y)"
paulson@14378
   654
by (simp add: real_of_int_def) 
paulson@14365
   655
declare real_of_int_diff [symmetric, simp]
paulson@14334
   656
paulson@14365
   657
lemma real_of_int_mult: "real (x::int) * real y = real (x * y)"
paulson@14378
   658
by (simp add: real_of_int_def) 
paulson@14365
   659
declare real_of_int_mult [symmetric, simp]
paulson@14365
   660
paulson@14365
   661
lemma real_of_int_zero_cancel [simp]: "(real x = 0) = (x = (0::int))"
paulson@14378
   662
by (simp add: real_of_int_def) 
paulson@14365
   663
paulson@14365
   664
lemma real_of_int_inject [iff]: "(real (x::int) = real y) = (x = y)"
paulson@14378
   665
by (simp add: real_of_int_def) 
paulson@14365
   666
paulson@14365
   667
lemma real_of_int_less_iff [iff]: "(real (x::int) < real y) = (x < y)"
paulson@14378
   668
by (simp add: real_of_int_def) 
paulson@14365
   669
paulson@14365
   670
lemma real_of_int_le_iff [simp]: "(real (x::int) \<le> real y) = (x \<le> y)"
paulson@14378
   671
by (simp add: real_of_int_def) 
paulson@14365
   672
paulson@14365
   673
paulson@14365
   674
subsection{*Embedding the Naturals into the Reals*}
paulson@14365
   675
paulson@14334
   676
lemma real_of_nat_zero [simp]: "real (0::nat) = 0"
paulson@14365
   677
by (simp add: real_of_nat_def)
paulson@14334
   678
paulson@14334
   679
lemma real_of_nat_one [simp]: "real (Suc 0) = (1::real)"
paulson@14365
   680
by (simp add: real_of_nat_def)
paulson@14334
   681
paulson@14365
   682
lemma real_of_nat_add [simp]: "real (m + n) = real (m::nat) + real n"
paulson@14378
   683
by (simp add: real_of_nat_def)
paulson@14334
   684
paulson@14334
   685
(*Not for addsimps: often the LHS is used to represent a positive natural*)
paulson@14334
   686
lemma real_of_nat_Suc: "real (Suc n) = real n + (1::real)"
paulson@14378
   687
by (simp add: real_of_nat_def)
paulson@14334
   688
paulson@14334
   689
lemma real_of_nat_less_iff [iff]: 
paulson@14334
   690
     "(real (n::nat) < real m) = (n < m)"
paulson@14365
   691
by (simp add: real_of_nat_def)
paulson@14334
   692
paulson@14334
   693
lemma real_of_nat_le_iff [iff]: "(real (n::nat) \<le> real m) = (n \<le> m)"
paulson@14378
   694
by (simp add: real_of_nat_def)
paulson@14334
   695
paulson@14334
   696
lemma real_of_nat_ge_zero [iff]: "0 \<le> real (n::nat)"
paulson@14378
   697
by (simp add: real_of_nat_def zero_le_imp_of_nat)
paulson@14334
   698
paulson@14365
   699
lemma real_of_nat_Suc_gt_zero: "0 < real (Suc n)"
paulson@14378
   700
by (simp add: real_of_nat_def del: of_nat_Suc)
paulson@14365
   701
paulson@14334
   702
lemma real_of_nat_mult [simp]: "real (m * n) = real (m::nat) * real n"
paulson@14378
   703
by (simp add: real_of_nat_def)
paulson@14334
   704
paulson@14334
   705
lemma real_of_nat_inject [iff]: "(real (n::nat) = real m) = (n = m)"
paulson@14378
   706
by (simp add: real_of_nat_def)
paulson@14334
   707
paulson@14387
   708
lemma real_of_nat_zero_iff [iff]: "(real (n::nat) = 0) = (n = 0)"
paulson@14378
   709
by (simp add: real_of_nat_def)
paulson@14334
   710
paulson@14365
   711
lemma real_of_nat_diff: "n \<le> m ==> real (m - n) = real (m::nat) - real n"
paulson@14378
   712
by (simp add: add: real_of_nat_def) 
paulson@14334
   713
paulson@14365
   714
lemma real_of_nat_gt_zero_cancel_iff [simp]: "(0 < real (n::nat)) = (0 < n)"
paulson@14378
   715
by (simp add: add: real_of_nat_def) 
paulson@14365
   716
paulson@14365
   717
lemma real_of_nat_le_zero_cancel_iff [simp]: "(real (n::nat) \<le> 0) = (n = 0)"
paulson@14378
   718
by (simp add: add: real_of_nat_def)
paulson@14334
   719
paulson@14365
   720
lemma not_real_of_nat_less_zero [simp]: "~ real (n::nat) < 0"
paulson@14378
   721
by (simp add: add: real_of_nat_def)
paulson@14334
   722
paulson@14365
   723
lemma real_of_nat_ge_zero_cancel_iff [simp]: "(0 \<le> real (n::nat)) = (0 \<le> n)"
paulson@14378
   724
by (simp add: add: real_of_nat_def)
paulson@14334
   725
paulson@14365
   726
lemma real_of_int_real_of_nat: "real (int n) = real n"
paulson@14378
   727
by (simp add: real_of_nat_def real_of_int_def int_eq_of_nat)
paulson@14378
   728
paulson@14426
   729
lemma real_of_int_of_nat_eq [simp]: "real (of_nat n :: int) = real n"
paulson@14426
   730
by (simp add: real_of_int_def real_of_nat_def)
paulson@14334
   731
paulson@14387
   732
paulson@14387
   733
paulson@14387
   734
subsection{*Numerals and Arithmetic*}
paulson@14387
   735
paulson@14387
   736
instance real :: number ..
paulson@14387
   737
paulson@15013
   738
defs (overloaded)
paulson@15013
   739
  real_number_of_def: "(number_of w :: real) == of_int (Rep_Bin w)"
paulson@15013
   740
    --{*the type constraint is essential!*}
paulson@14387
   741
paulson@14387
   742
instance real :: number_ring
paulson@15013
   743
by (intro_classes, simp add: real_number_of_def) 
paulson@14387
   744
paulson@14387
   745
paulson@14387
   746
text{*Collapse applications of @{term real} to @{term number_of}*}
paulson@14387
   747
lemma real_number_of [simp]: "real (number_of v :: int) = number_of v"
paulson@14387
   748
by (simp add:  real_of_int_def of_int_number_of_eq)
paulson@14387
   749
paulson@14387
   750
lemma real_of_nat_number_of [simp]:
paulson@14387
   751
     "real (number_of v :: nat) =  
paulson@14387
   752
        (if neg (number_of v :: int) then 0  
paulson@14387
   753
         else (number_of v :: real))"
paulson@14387
   754
by (simp add: real_of_int_real_of_nat [symmetric] int_nat_number_of)
paulson@14387
   755
 
paulson@14387
   756
paulson@14387
   757
use "real_arith.ML"
paulson@14387
   758
paulson@14387
   759
setup real_arith_setup
paulson@14387
   760
paulson@14387
   761
subsection{* Simprules combining x+y and 0: ARE THEY NEEDED?*}
paulson@14387
   762
paulson@14387
   763
text{*Needed in this non-standard form by Hyperreal/Transcendental*}
paulson@14387
   764
lemma real_0_le_divide_iff:
paulson@14387
   765
     "((0::real) \<le> x/y) = ((x \<le> 0 | 0 \<le> y) & (0 \<le> x | y \<le> 0))"
paulson@14387
   766
by (simp add: real_divide_def zero_le_mult_iff, auto)
paulson@14387
   767
paulson@14387
   768
lemma real_add_minus_iff [simp]: "(x + - a = (0::real)) = (x=a)" 
paulson@14387
   769
by arith
paulson@14387
   770
paulson@15085
   771
lemma real_add_eq_0_iff: "(x+y = (0::real)) = (y = -x)"
paulson@14387
   772
by auto
paulson@14387
   773
paulson@15085
   774
lemma real_add_less_0_iff: "(x+y < (0::real)) = (y < -x)"
paulson@14387
   775
by auto
paulson@14387
   776
paulson@15085
   777
lemma real_0_less_add_iff: "((0::real) < x+y) = (-x < y)"
paulson@14387
   778
by auto
paulson@14387
   779
paulson@15085
   780
lemma real_add_le_0_iff: "(x+y \<le> (0::real)) = (y \<le> -x)"
paulson@14387
   781
by auto
paulson@14387
   782
paulson@15085
   783
lemma real_0_le_add_iff: "((0::real) \<le> x+y) = (-x \<le> y)"
paulson@14387
   784
by auto
paulson@14387
   785
paulson@14387
   786
paulson@14387
   787
(*
paulson@14387
   788
FIXME: we should have this, as for type int, but many proofs would break.
paulson@14387
   789
It replaces x+-y by x-y.
paulson@15086
   790
declare real_diff_def [symmetric, simp]
paulson@14387
   791
*)
paulson@14387
   792
paulson@14387
   793
paulson@14387
   794
subsubsection{*Density of the Reals*}
paulson@14387
   795
paulson@14387
   796
lemma real_lbound_gt_zero:
paulson@14387
   797
     "[| (0::real) < d1; 0 < d2 |] ==> \<exists>e. 0 < e & e < d1 & e < d2"
paulson@14387
   798
apply (rule_tac x = " (min d1 d2) /2" in exI)
paulson@14387
   799
apply (simp add: min_def)
paulson@14387
   800
done
paulson@14387
   801
paulson@14387
   802
paulson@14387
   803
text{*Similar results are proved in @{text Ring_and_Field}*}
paulson@14387
   804
lemma real_less_half_sum: "x < y ==> x < (x+y) / (2::real)"
paulson@14387
   805
  by auto
paulson@14387
   806
paulson@14387
   807
lemma real_gt_half_sum: "x < y ==> (x+y)/(2::real) < y"
paulson@14387
   808
  by auto
paulson@14387
   809
paulson@14387
   810
paulson@14387
   811
subsection{*Absolute Value Function for the Reals*}
paulson@14387
   812
paulson@14387
   813
lemma abs_minus_add_cancel: "abs(x + (-y)) = abs (y + (-(x::real)))"
paulson@15003
   814
by (simp add: abs_if)
paulson@14387
   815
paulson@14387
   816
lemma abs_interval_iff: "(abs x < r) = (-r < x & x < (r::real))"
paulson@14387
   817
by (force simp add: Ring_and_Field.abs_less_iff)
paulson@14387
   818
paulson@14387
   819
lemma abs_le_interval_iff: "(abs x \<le> r) = (-r\<le>x & x\<le>(r::real))"
obua@14738
   820
by (force simp add: OrderedGroup.abs_le_iff)
paulson@14387
   821
paulson@14484
   822
(*FIXME: used only once, in SEQ.ML*)
paulson@14387
   823
lemma abs_add_one_gt_zero [simp]: "(0::real) < 1 + abs(x)"
paulson@15003
   824
by (simp add: abs_if)
paulson@14387
   825
paulson@14387
   826
lemma abs_real_of_nat_cancel [simp]: "abs (real x) = real (x::nat)"
paulson@15229
   827
by (simp add: real_of_nat_ge_zero)
paulson@14387
   828
paulson@14387
   829
lemma abs_add_one_not_less_self [simp]: "~ abs(x) + (1::real) < x"
paulson@14387
   830
apply (simp add: linorder_not_less)
paulson@14387
   831
apply (auto intro: abs_ge_self [THEN order_trans])
paulson@14387
   832
done
paulson@14387
   833
 
paulson@14387
   834
text{*Used only in Hyperreal/Lim.ML*}
paulson@14387
   835
lemma abs_sum_triangle_ineq: "abs ((x::real) + y + (-l + -m)) \<le> abs(x + -l) + abs(y + -m)"
paulson@14387
   836
apply (simp add: real_add_assoc)
paulson@14387
   837
apply (rule_tac a1 = y in add_left_commute [THEN ssubst])
paulson@14387
   838
apply (rule real_add_assoc [THEN subst])
paulson@14387
   839
apply (rule abs_triangle_ineq)
paulson@14387
   840
done
paulson@14387
   841
paulson@14387
   842
paulson@14387
   843
paulson@14334
   844
ML
paulson@14334
   845
{*
paulson@14387
   846
val real_lbound_gt_zero = thm"real_lbound_gt_zero";
paulson@14387
   847
val real_less_half_sum = thm"real_less_half_sum";
paulson@14387
   848
val real_gt_half_sum = thm"real_gt_half_sum";
paulson@14341
   849
paulson@14387
   850
val abs_interval_iff = thm"abs_interval_iff";
paulson@14387
   851
val abs_le_interval_iff = thm"abs_le_interval_iff";
paulson@14387
   852
val abs_add_one_gt_zero = thm"abs_add_one_gt_zero";
paulson@14387
   853
val abs_add_one_not_less_self = thm"abs_add_one_not_less_self";
paulson@14387
   854
val abs_sum_triangle_ineq = thm"abs_sum_triangle_ineq";
paulson@14334
   855
*}
paulson@10752
   856
paulson@14387
   857
paulson@5588
   858
end