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Sequences that converge to the same point


Cauchy Sequences and Analysistopology - triangle inequalityConvergence and metric - Proof?Complete metric on the space of sequencesConverge in mean square of sum of random variablesProve that if two sequences converge to the same value but their image sequences converge to different values, then the limit DNEProve that either both sequences converge to the same limit or both diverge.Completion of metric space (via formal limits of Cauchy sequences)Proving completeness of space of converging sequencesFind non convergent Cauchy sequence













0












$begingroup$


In $(X,d)$ metric space, If $x_n_ninBbb N$ and $y_n_ninBbb N$ are two sequences which converge to the same point, then prove that



$$lim_ntoinfty d(x_n,y_n)=0$$



This question is found in the chapter of completeness, but I could not figure out where to use completeness for this question.










share|cite|improve this question











$endgroup$











  • $begingroup$
    You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
    $endgroup$
    – user228113
    May 11 '17 at 13:27
















0












$begingroup$


In $(X,d)$ metric space, If $x_n_ninBbb N$ and $y_n_ninBbb N$ are two sequences which converge to the same point, then prove that



$$lim_ntoinfty d(x_n,y_n)=0$$



This question is found in the chapter of completeness, but I could not figure out where to use completeness for this question.










share|cite|improve this question











$endgroup$











  • $begingroup$
    You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
    $endgroup$
    – user228113
    May 11 '17 at 13:27














0












0








0





$begingroup$


In $(X,d)$ metric space, If $x_n_ninBbb N$ and $y_n_ninBbb N$ are two sequences which converge to the same point, then prove that



$$lim_ntoinfty d(x_n,y_n)=0$$



This question is found in the chapter of completeness, but I could not figure out where to use completeness for this question.










share|cite|improve this question











$endgroup$




In $(X,d)$ metric space, If $x_n_ninBbb N$ and $y_n_ninBbb N$ are two sequences which converge to the same point, then prove that



$$lim_ntoinfty d(x_n,y_n)=0$$



This question is found in the chapter of completeness, but I could not figure out where to use completeness for this question.







convergence metric-spaces complete-spaces






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited May 11 '17 at 13:25







user228113

















asked May 11 '17 at 13:14









Jonathan S.Jonathan S.

82




82











  • $begingroup$
    You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
    $endgroup$
    – user228113
    May 11 '17 at 13:27

















  • $begingroup$
    You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
    $endgroup$
    – user228113
    May 11 '17 at 13:27
















$begingroup$
You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
$endgroup$
– user228113
May 11 '17 at 13:27





$begingroup$
You do not need to use completeness in any shape or form. The result is true regardless of even mentioning it.
$endgroup$
– user228113
May 11 '17 at 13:27











3 Answers
3






active

oldest

votes


















0












$begingroup$

let $X_nrightarrow X$ thus $Y_n$ converges to Y as well. Given $epsilon>0$, $exists min N$ such that $forall n>m$ $d(X_n,X)<epsilon /2$ and $d(Y_n,X)<epsilon /2$ Then $forall n>m $ we have $d(X_n,Y_n)<d(X-n,X)+d(Y_n,X)<epsilon$. Thus $d(X_n,Y_n)rightarrow 0$






share|cite|improve this answer









$endgroup$




















    0












    $begingroup$

    Hint:



    If $x$ is the limit of $x_n$ and $y$ is the limit of $y_n$, then



    $$d(x_n, y_n) leq d(x_n, x) + d(x, y) + d(y, y_n)$$



    You can use this to prove (using the $epsilon$ -definition) that $$lim_ntoinfty d(x_n, y_n) = 0$$






    share|cite|improve this answer









    $endgroup$




















      0












      $begingroup$

      Let $l$ be the limit of the sequences $(x_n), (y_n)$ by definition Note that $d(x_n,y_n) leq d(x_n,l) + d(l, y_n)$ for all $n$. If $varepsilon > 0$, then there are $N_1,N_2$, by assumption, giving $d(x_n,l), d(l,y_n) < varepsilon/2$ for all $n geq N_1$ and $geq N_2$. So $d(x_n,l) + d(l,y_n) < varepsilon$ for all $n geq max N_1,N_2 $; so $d(x_n,y_n) < varepsilon$ for all $n geq max N_1,N_2 $.






      share|cite|improve this answer









      $endgroup$












        Your Answer





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        3 Answers
        3






        active

        oldest

        votes








        3 Answers
        3






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes









        0












        $begingroup$

        let $X_nrightarrow X$ thus $Y_n$ converges to Y as well. Given $epsilon>0$, $exists min N$ such that $forall n>m$ $d(X_n,X)<epsilon /2$ and $d(Y_n,X)<epsilon /2$ Then $forall n>m $ we have $d(X_n,Y_n)<d(X-n,X)+d(Y_n,X)<epsilon$. Thus $d(X_n,Y_n)rightarrow 0$






        share|cite|improve this answer









        $endgroup$

















          0












          $begingroup$

          let $X_nrightarrow X$ thus $Y_n$ converges to Y as well. Given $epsilon>0$, $exists min N$ such that $forall n>m$ $d(X_n,X)<epsilon /2$ and $d(Y_n,X)<epsilon /2$ Then $forall n>m $ we have $d(X_n,Y_n)<d(X-n,X)+d(Y_n,X)<epsilon$. Thus $d(X_n,Y_n)rightarrow 0$






          share|cite|improve this answer









          $endgroup$















            0












            0








            0





            $begingroup$

            let $X_nrightarrow X$ thus $Y_n$ converges to Y as well. Given $epsilon>0$, $exists min N$ such that $forall n>m$ $d(X_n,X)<epsilon /2$ and $d(Y_n,X)<epsilon /2$ Then $forall n>m $ we have $d(X_n,Y_n)<d(X-n,X)+d(Y_n,X)<epsilon$. Thus $d(X_n,Y_n)rightarrow 0$






            share|cite|improve this answer









            $endgroup$



            let $X_nrightarrow X$ thus $Y_n$ converges to Y as well. Given $epsilon>0$, $exists min N$ such that $forall n>m$ $d(X_n,X)<epsilon /2$ and $d(Y_n,X)<epsilon /2$ Then $forall n>m $ we have $d(X_n,Y_n)<d(X-n,X)+d(Y_n,X)<epsilon$. Thus $d(X_n,Y_n)rightarrow 0$







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered May 11 '17 at 13:20







            user379195




























                0












                $begingroup$

                Hint:



                If $x$ is the limit of $x_n$ and $y$ is the limit of $y_n$, then



                $$d(x_n, y_n) leq d(x_n, x) + d(x, y) + d(y, y_n)$$



                You can use this to prove (using the $epsilon$ -definition) that $$lim_ntoinfty d(x_n, y_n) = 0$$






                share|cite|improve this answer









                $endgroup$

















                  0












                  $begingroup$

                  Hint:



                  If $x$ is the limit of $x_n$ and $y$ is the limit of $y_n$, then



                  $$d(x_n, y_n) leq d(x_n, x) + d(x, y) + d(y, y_n)$$



                  You can use this to prove (using the $epsilon$ -definition) that $$lim_ntoinfty d(x_n, y_n) = 0$$






                  share|cite|improve this answer









                  $endgroup$















                    0












                    0








                    0





                    $begingroup$

                    Hint:



                    If $x$ is the limit of $x_n$ and $y$ is the limit of $y_n$, then



                    $$d(x_n, y_n) leq d(x_n, x) + d(x, y) + d(y, y_n)$$



                    You can use this to prove (using the $epsilon$ -definition) that $$lim_ntoinfty d(x_n, y_n) = 0$$






                    share|cite|improve this answer









                    $endgroup$



                    Hint:



                    If $x$ is the limit of $x_n$ and $y$ is the limit of $y_n$, then



                    $$d(x_n, y_n) leq d(x_n, x) + d(x, y) + d(y, y_n)$$



                    You can use this to prove (using the $epsilon$ -definition) that $$lim_ntoinfty d(x_n, y_n) = 0$$







                    share|cite|improve this answer












                    share|cite|improve this answer



                    share|cite|improve this answer










                    answered May 11 '17 at 13:16









                    5xum5xum

                    91.4k394161




                    91.4k394161





















                        0












                        $begingroup$

                        Let $l$ be the limit of the sequences $(x_n), (y_n)$ by definition Note that $d(x_n,y_n) leq d(x_n,l) + d(l, y_n)$ for all $n$. If $varepsilon > 0$, then there are $N_1,N_2$, by assumption, giving $d(x_n,l), d(l,y_n) < varepsilon/2$ for all $n geq N_1$ and $geq N_2$. So $d(x_n,l) + d(l,y_n) < varepsilon$ for all $n geq max N_1,N_2 $; so $d(x_n,y_n) < varepsilon$ for all $n geq max N_1,N_2 $.






                        share|cite|improve this answer









                        $endgroup$

















                          0












                          $begingroup$

                          Let $l$ be the limit of the sequences $(x_n), (y_n)$ by definition Note that $d(x_n,y_n) leq d(x_n,l) + d(l, y_n)$ for all $n$. If $varepsilon > 0$, then there are $N_1,N_2$, by assumption, giving $d(x_n,l), d(l,y_n) < varepsilon/2$ for all $n geq N_1$ and $geq N_2$. So $d(x_n,l) + d(l,y_n) < varepsilon$ for all $n geq max N_1,N_2 $; so $d(x_n,y_n) < varepsilon$ for all $n geq max N_1,N_2 $.






                          share|cite|improve this answer









                          $endgroup$















                            0












                            0








                            0





                            $begingroup$

                            Let $l$ be the limit of the sequences $(x_n), (y_n)$ by definition Note that $d(x_n,y_n) leq d(x_n,l) + d(l, y_n)$ for all $n$. If $varepsilon > 0$, then there are $N_1,N_2$, by assumption, giving $d(x_n,l), d(l,y_n) < varepsilon/2$ for all $n geq N_1$ and $geq N_2$. So $d(x_n,l) + d(l,y_n) < varepsilon$ for all $n geq max N_1,N_2 $; so $d(x_n,y_n) < varepsilon$ for all $n geq max N_1,N_2 $.






                            share|cite|improve this answer









                            $endgroup$



                            Let $l$ be the limit of the sequences $(x_n), (y_n)$ by definition Note that $d(x_n,y_n) leq d(x_n,l) + d(l, y_n)$ for all $n$. If $varepsilon > 0$, then there are $N_1,N_2$, by assumption, giving $d(x_n,l), d(l,y_n) < varepsilon/2$ for all $n geq N_1$ and $geq N_2$. So $d(x_n,l) + d(l,y_n) < varepsilon$ for all $n geq max N_1,N_2 $; so $d(x_n,y_n) < varepsilon$ for all $n geq max N_1,N_2 $.







                            share|cite|improve this answer












                            share|cite|improve this answer



                            share|cite|improve this answer










                            answered May 11 '17 at 13:37









                            Gary MooreGary Moore

                            17.3k21546




                            17.3k21546



























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