Is it true $P(cap_{n=1}^infty cup_{m=n}^infty A_m)=lim_{n to infty}P(cup_{m=n}^infty A_m)$?












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I just need some confirmation on the truth of this since I didn't see it in a textbook so far. I think it is true by continuity of probability. Am I right?










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    I just need some confirmation on the truth of this since I didn't see it in a textbook so far. I think it is true by continuity of probability. Am I right?










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      I just need some confirmation on the truth of this since I didn't see it in a textbook so far. I think it is true by continuity of probability. Am I right?










      share|cite|improve this question









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      I just need some confirmation on the truth of this since I didn't see it in a textbook so far. I think it is true by continuity of probability. Am I right?







      probability measure-theory






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      asked Dec 6 '18 at 3:16









      Daniel LiDaniel Li

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          For each $n in mathbb N$, let $B_n=bigcup_{m=n}^infty A_m $. Clearly for each $n in mathbb N$ we have $B_n supseteq B_{n+1}$, and so ${B_n}_{n=1}^infty$ is a decreasing sequence of sets. Moreover, $P(B_1)<infty$ as a probability measure is finite. Therefore, $$Pleft(bigcap_{n=1}^infty B_nright)=lim_{nto infty} P(B_n)$$ by the continuity from above property of a measure which is $(3')$ here.






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            Let $B_n:=bigcup_{mge n}A_m$. Then $B_{n+1}subseteq B_n$ and by continuity from above,
            $$
            mathsf{P}left(bigcap_{nge 1} B_nright)=lim_{ntoinfty} mathsf{P}(B_n).
            $$






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              2 Answers
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              $begingroup$

              For each $n in mathbb N$, let $B_n=bigcup_{m=n}^infty A_m $. Clearly for each $n in mathbb N$ we have $B_n supseteq B_{n+1}$, and so ${B_n}_{n=1}^infty$ is a decreasing sequence of sets. Moreover, $P(B_1)<infty$ as a probability measure is finite. Therefore, $$Pleft(bigcap_{n=1}^infty B_nright)=lim_{nto infty} P(B_n)$$ by the continuity from above property of a measure which is $(3')$ here.






              share|cite|improve this answer











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                $begingroup$

                For each $n in mathbb N$, let $B_n=bigcup_{m=n}^infty A_m $. Clearly for each $n in mathbb N$ we have $B_n supseteq B_{n+1}$, and so ${B_n}_{n=1}^infty$ is a decreasing sequence of sets. Moreover, $P(B_1)<infty$ as a probability measure is finite. Therefore, $$Pleft(bigcap_{n=1}^infty B_nright)=lim_{nto infty} P(B_n)$$ by the continuity from above property of a measure which is $(3')$ here.






                share|cite|improve this answer











                $endgroup$
















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                  $begingroup$

                  For each $n in mathbb N$, let $B_n=bigcup_{m=n}^infty A_m $. Clearly for each $n in mathbb N$ we have $B_n supseteq B_{n+1}$, and so ${B_n}_{n=1}^infty$ is a decreasing sequence of sets. Moreover, $P(B_1)<infty$ as a probability measure is finite. Therefore, $$Pleft(bigcap_{n=1}^infty B_nright)=lim_{nto infty} P(B_n)$$ by the continuity from above property of a measure which is $(3')$ here.






                  share|cite|improve this answer











                  $endgroup$



                  For each $n in mathbb N$, let $B_n=bigcup_{m=n}^infty A_m $. Clearly for each $n in mathbb N$ we have $B_n supseteq B_{n+1}$, and so ${B_n}_{n=1}^infty$ is a decreasing sequence of sets. Moreover, $P(B_1)<infty$ as a probability measure is finite. Therefore, $$Pleft(bigcap_{n=1}^infty B_nright)=lim_{nto infty} P(B_n)$$ by the continuity from above property of a measure which is $(3')$ here.







                  share|cite|improve this answer














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                  edited Dec 6 '18 at 4:05

























                  answered Dec 6 '18 at 3:38









                  Matt A PeltoMatt A Pelto

                  2,537620




                  2,537620























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                      $begingroup$

                      Let $B_n:=bigcup_{mge n}A_m$. Then $B_{n+1}subseteq B_n$ and by continuity from above,
                      $$
                      mathsf{P}left(bigcap_{nge 1} B_nright)=lim_{ntoinfty} mathsf{P}(B_n).
                      $$






                      share|cite|improve this answer











                      $endgroup$


















                        3












                        $begingroup$

                        Let $B_n:=bigcup_{mge n}A_m$. Then $B_{n+1}subseteq B_n$ and by continuity from above,
                        $$
                        mathsf{P}left(bigcap_{nge 1} B_nright)=lim_{ntoinfty} mathsf{P}(B_n).
                        $$






                        share|cite|improve this answer











                        $endgroup$
















                          3












                          3








                          3





                          $begingroup$

                          Let $B_n:=bigcup_{mge n}A_m$. Then $B_{n+1}subseteq B_n$ and by continuity from above,
                          $$
                          mathsf{P}left(bigcap_{nge 1} B_nright)=lim_{ntoinfty} mathsf{P}(B_n).
                          $$






                          share|cite|improve this answer











                          $endgroup$



                          Let $B_n:=bigcup_{mge n}A_m$. Then $B_{n+1}subseteq B_n$ and by continuity from above,
                          $$
                          mathsf{P}left(bigcap_{nge 1} B_nright)=lim_{ntoinfty} mathsf{P}(B_n).
                          $$







                          share|cite|improve this answer














                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited Dec 6 '18 at 4:00

























                          answered Dec 6 '18 at 3:32









                          d.k.o.d.k.o.

                          9,145628




                          9,145628






























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