src/HOL/Limits.thy
changeset 63548 6c2c16fef8f1
parent 63546 5f097087fa1e
child 63556 36e9732988ce
equal deleted inserted replaced
63547:00521f181510 63548:6c2c16fef8f1
  2078   with \<open>decseq X\<close> show "\<exists>L. X \<longlonglongrightarrow> L \<and> (\<forall>i. L \<le> X i)"
  2078   with \<open>decseq X\<close> show "\<exists>L. X \<longlonglongrightarrow> L \<and> (\<forall>i. L \<le> X i)"
  2079     by (auto intro!: exI[of _ L] decseq_le)
  2079     by (auto intro!: exI[of _ L] decseq_le)
  2080 qed
  2080 qed
  2081 
  2081 
  2082 
  2082 
  2083 subsubsection \<open>Cauchy Sequences are Bounded\<close>
       
  2084 
       
  2085 text \<open>
       
  2086   A Cauchy sequence is bounded -- this is the standard
       
  2087   proof mechanization rather than the nonstandard proof.
       
  2088 \<close>
       
  2089 
       
  2090 lemma lemmaCauchy: "\<forall>n \<ge> M. norm (X M - X n) < (1::real) \<Longrightarrow>
       
  2091   \<forall>n \<ge> M. norm (X n :: 'a::real_normed_vector) < 1 + norm (X M)"
       
  2092   apply clarify
       
  2093   apply (drule spec)
       
  2094   apply (drule (1) mp)
       
  2095   apply (simp only: norm_minus_commute)
       
  2096   apply (drule order_le_less_trans [OF norm_triangle_ineq2])
       
  2097   apply simp
       
  2098   done
       
  2099 
       
  2100 
       
  2101 subsection \<open>Power Sequences\<close>
  2083 subsection \<open>Power Sequences\<close>
  2102 
  2084 
  2103 text \<open>
  2085 text \<open>
  2104   The sequence @{term "x^n"} tends to 0 if @{term "0\<le>x"} and @{term
  2086   The sequence @{term "x^n"} tends to 0 if @{term "0\<le>x"} and @{term
  2105   "x<1"}.  Proof will use (NS) Cauchy equivalence for convergence and
  2087   "x<1"}.  Proof will use (NS) Cauchy equivalence for convergence and