src/HOL/RComplete.thy
changeset 51520 e9b361845809
parent 51519 2831ce75ec49
equal deleted inserted replaced
51519:2831ce75ec49 51520:e9b361845809
     6 *)
     6 *)
     7 
     7 
     8 header {* Completeness of the Reals; Floor and Ceiling Functions *}
     8 header {* Completeness of the Reals; Floor and Ceiling Functions *}
     9 
     9 
    10 theory RComplete
    10 theory RComplete
    11 imports Conditional_Complete_Lattices RealDef
    11 imports RealDef
    12 begin
    12 begin
    13 
       
    14 lemma real_sum_of_halves: "x/2 + x/2 = (x::real)"
       
    15   by simp
       
    16 
       
    17 lemma abs_diff_less_iff:
       
    18   "(\<bar>x - a\<bar> < (r::'a::linordered_idom)) = (a - r < x \<and> x < a + r)"
       
    19   by auto
       
    20 
    13 
    21 subsection {* Completeness of Positive Reals *}
    14 subsection {* Completeness of Positive Reals *}
    22 
    15 
    23 text {*
    16 text {*
    24   \medskip Completeness properties using @{text "isUb"}, @{text "isLub"} etc.
    17   \medskip Completeness properties using @{text "isUb"}, @{text "isLub"} etc.
    25 *}
    18 *}
    26 
       
    27 lemma real_isLub_unique: "[| isLub R S x; isLub R S y |] ==> x = (y::real)"
       
    28   apply (frule isLub_isUb)
       
    29   apply (frule_tac x = y in isLub_isUb)
       
    30   apply (blast intro!: order_antisym dest!: isLub_le_isUb)
       
    31   done
       
    32 
       
    33 
    19 
    34 text {*
    20 text {*
    35   \medskip reals Completeness (again!)
    21   \medskip reals Completeness (again!)
    36 *}
    22 *}
    37 
    23