src/HOL/Library/Indicator_Function.thy
changeset 67683 817944aeac3f
parent 64966 d53d7ca3303e
child 69313 b021008c5397
equal deleted inserted replaced
67682:00c436488398 67683:817944aeac3f
     7 theory Indicator_Function
     7 theory Indicator_Function
     8 imports Complex_Main Disjoint_Sets
     8 imports Complex_Main Disjoint_Sets
     9 begin
     9 begin
    10 
    10 
    11 definition "indicator S x = (if x \<in> S then 1 else 0)"
    11 definition "indicator S x = (if x \<in> S then 1 else 0)"
       
    12 
       
    13 text\<open>Type constrained version\<close>
       
    14 abbreviation indicat_real :: "'a set \<Rightarrow> 'a \<Rightarrow> real" where "indicat_real S \<equiv> indicator S"
    12 
    15 
    13 lemma indicator_simps[simp]:
    16 lemma indicator_simps[simp]:
    14   "x \<in> S \<Longrightarrow> indicator S x = 1"
    17   "x \<in> S \<Longrightarrow> indicator S x = 1"
    15   "x \<notin> S \<Longrightarrow> indicator S x = 0"
    18   "x \<notin> S \<Longrightarrow> indicator S x = 0"
    16   unfolding indicator_def by auto
    19   unfolding indicator_def by auto