Let $Y$ and $Z$ be completions of $X$, then there exists an isometry from $Y$ onto $Z$.

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Proof Attempt: Let $X$ be dense on metric spaces $Y$ and $Z$.
Let $overlineX=Y$ and $overlineX=Z$. Suppose that $a_n$ is a sequence in $A$ such that $a_nrightarrow y,z$ such that $yin Y$ and $zin Z$. Let $MinBbbN$ be such that $forall igeq M$, we have $d_Y(y,a_i),d_Z(z,a_i)ltepsilon/2$. Then, we extend the identity mapping on $X$, by defining $i(y)=z$. Hence, we have
beginalign
vert d_Y(y,a_i)-d_Z(i(y),i(a_i))vert=vert d_Y(y,a_i)-d_Z(z,a_i)vertltepsilon
endalign
This means $forall yin Y$, $forall zin Z$, and for all sequences $a_nrightarrow y,z$ in $X$, we have $d_Y(y,a_i)=d_Z(z,a_i)$ - an isometry.







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  • How do you define $overline X = Y$?
    – Kenny Lau
    Aug 1 at 9:07










  • I just edited. I meant closure of the metric space.
    – TheLast Cipher
    Aug 1 at 9:09










  • How do you define closure?
    – Kenny Lau
    Aug 1 at 9:09










  • set of all limit points of the space.
    – TheLast Cipher
    Aug 1 at 9:11










  • I don't think that is quite well-defined.
    – Kenny Lau
    Aug 1 at 9:11














up vote
0
down vote

favorite












Proof Attempt: Let $X$ be dense on metric spaces $Y$ and $Z$.
Let $overlineX=Y$ and $overlineX=Z$. Suppose that $a_n$ is a sequence in $A$ such that $a_nrightarrow y,z$ such that $yin Y$ and $zin Z$. Let $MinBbbN$ be such that $forall igeq M$, we have $d_Y(y,a_i),d_Z(z,a_i)ltepsilon/2$. Then, we extend the identity mapping on $X$, by defining $i(y)=z$. Hence, we have
beginalign
vert d_Y(y,a_i)-d_Z(i(y),i(a_i))vert=vert d_Y(y,a_i)-d_Z(z,a_i)vertltepsilon
endalign
This means $forall yin Y$, $forall zin Z$, and for all sequences $a_nrightarrow y,z$ in $X$, we have $d_Y(y,a_i)=d_Z(z,a_i)$ - an isometry.







share|cite|improve this question





















  • How do you define $overline X = Y$?
    – Kenny Lau
    Aug 1 at 9:07










  • I just edited. I meant closure of the metric space.
    – TheLast Cipher
    Aug 1 at 9:09










  • How do you define closure?
    – Kenny Lau
    Aug 1 at 9:09










  • set of all limit points of the space.
    – TheLast Cipher
    Aug 1 at 9:11










  • I don't think that is quite well-defined.
    – Kenny Lau
    Aug 1 at 9:11












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Proof Attempt: Let $X$ be dense on metric spaces $Y$ and $Z$.
Let $overlineX=Y$ and $overlineX=Z$. Suppose that $a_n$ is a sequence in $A$ such that $a_nrightarrow y,z$ such that $yin Y$ and $zin Z$. Let $MinBbbN$ be such that $forall igeq M$, we have $d_Y(y,a_i),d_Z(z,a_i)ltepsilon/2$. Then, we extend the identity mapping on $X$, by defining $i(y)=z$. Hence, we have
beginalign
vert d_Y(y,a_i)-d_Z(i(y),i(a_i))vert=vert d_Y(y,a_i)-d_Z(z,a_i)vertltepsilon
endalign
This means $forall yin Y$, $forall zin Z$, and for all sequences $a_nrightarrow y,z$ in $X$, we have $d_Y(y,a_i)=d_Z(z,a_i)$ - an isometry.







share|cite|improve this question













Proof Attempt: Let $X$ be dense on metric spaces $Y$ and $Z$.
Let $overlineX=Y$ and $overlineX=Z$. Suppose that $a_n$ is a sequence in $A$ such that $a_nrightarrow y,z$ such that $yin Y$ and $zin Z$. Let $MinBbbN$ be such that $forall igeq M$, we have $d_Y(y,a_i),d_Z(z,a_i)ltepsilon/2$. Then, we extend the identity mapping on $X$, by defining $i(y)=z$. Hence, we have
beginalign
vert d_Y(y,a_i)-d_Z(i(y),i(a_i))vert=vert d_Y(y,a_i)-d_Z(z,a_i)vertltepsilon
endalign
This means $forall yin Y$, $forall zin Z$, and for all sequences $a_nrightarrow y,z$ in $X$, we have $d_Y(y,a_i)=d_Z(z,a_i)$ - an isometry.









share|cite|improve this question












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edited Aug 1 at 9:13
























asked Aug 1 at 9:07









TheLast Cipher

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538414











  • How do you define $overline X = Y$?
    – Kenny Lau
    Aug 1 at 9:07










  • I just edited. I meant closure of the metric space.
    – TheLast Cipher
    Aug 1 at 9:09










  • How do you define closure?
    – Kenny Lau
    Aug 1 at 9:09










  • set of all limit points of the space.
    – TheLast Cipher
    Aug 1 at 9:11










  • I don't think that is quite well-defined.
    – Kenny Lau
    Aug 1 at 9:11
















  • How do you define $overline X = Y$?
    – Kenny Lau
    Aug 1 at 9:07










  • I just edited. I meant closure of the metric space.
    – TheLast Cipher
    Aug 1 at 9:09










  • How do you define closure?
    – Kenny Lau
    Aug 1 at 9:09










  • set of all limit points of the space.
    – TheLast Cipher
    Aug 1 at 9:11










  • I don't think that is quite well-defined.
    – Kenny Lau
    Aug 1 at 9:11















How do you define $overline X = Y$?
– Kenny Lau
Aug 1 at 9:07




How do you define $overline X = Y$?
– Kenny Lau
Aug 1 at 9:07












I just edited. I meant closure of the metric space.
– TheLast Cipher
Aug 1 at 9:09




I just edited. I meant closure of the metric space.
– TheLast Cipher
Aug 1 at 9:09












How do you define closure?
– Kenny Lau
Aug 1 at 9:09




How do you define closure?
– Kenny Lau
Aug 1 at 9:09












set of all limit points of the space.
– TheLast Cipher
Aug 1 at 9:11




set of all limit points of the space.
– TheLast Cipher
Aug 1 at 9:11












I don't think that is quite well-defined.
– Kenny Lau
Aug 1 at 9:11




I don't think that is quite well-defined.
– Kenny Lau
Aug 1 at 9:11















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