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@@ -577,24 +577,24 @@ The definition derives the ordering on morphisms of each hom-set $\Hom(X,\sub Y)
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\end{cases}
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\end{gather*}
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First, we need to prove that $\mu'$ is a subdistribution.
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For every $x \in X$, $\mu'(x) \ge 0$. The total mass of $\mu'$ is
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For every $x \in X$, $\mu'(x) \ge 0$. We have:
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\begin{align*}
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\sum_{x \in X} \mu'(x)&\\
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=& \sum_{x \in X} \frac{\nu(g(x))}{Sg(\mu)(g(x))} \comp \mu(x)\\
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=& \sum_{y \in Y} \sum_{x \in g^{\mone}(y)} \frac{\nu(y)}{Sg(\mu)(y)} \comp \mu(x)\\
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=& \sum_{y \in Y} \frac{\nu(y)}{Sg(\mu)(y)} \comp \sum_{x \in g^{\mone}(y)} \mu(x)\\
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=& \sum_{y \in Y} \frac{\nu(y)}{Sg(\mu)(y)} \comp Sg(\mu)(y)\\
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=& \sum_{x \in X} \frac{\nu(g(x))}{Sg(\mu)(g(x))} \comp \mu(x)&(Sg(\mu)(g(x))\neq 0)\\
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=& \sum_{y \in Y} \sum_{x \in g^{\mone}(y)} \frac{\nu(y)}{Sg(\mu)(y)} \comp \mu(x)&(Sg(\mu)(g(x))\neq 0)\\
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=& \sum_{y \in Y} \frac{\nu(y)}{Sg(\mu)(y)} \comp \sum_{x \in g^{\mone}(y)} \mu(x)&(Sg(\mu)(g(x))\neq 0)\\
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=& \sum_{y \in Y} \frac{\nu(y)}{Sg(\mu)(y)} \comp Sg(\mu)(y)&(Sg(\mu)(g(x))\neq 0)\\
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=& \sum_{y \in Y} \nu(y)\\
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\leq& 1
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\end{align*}
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Thus $\mu'$ is a subdistribution. Now, we prove $Sg(\mu') = \nu$.
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As for every $x\in X$ that $Sg(\mu)(g(x))=0$, $\mu'(x)=0$, it does not have effect the inequality. Thus $\mu'$ is a subdistribution. Now, we prove $Sg(\mu') = \nu$.
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For any $y \in Y$, we have:
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\begin{align*}
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Sg(\mu')(y)&\\
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= &\sum_{x \in g^{\mone}(y)} \mu'(x)\\
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= &\sum_{x \in g^{\mone}(y)} \frac{\nu(y)}{Sg(\mu)(y)} \comp \mu(x)\;\;(Sg(\mu)(y)\neq 0)\\
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= &\frac{\nu(y)}{Sg(\mu)(y)} \comp \sum_{x \in g^{\mone}(y)} \mu(x)\;\;(Sg(\mu)(y)\neq 0)\\
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= &\frac{\nu(y)}{Sg(\mu)(y)} \comp Sg(\mu)(y)\;\;(Sg(\mu)(y)\neq 0)\\
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= &\sum_{x \in g^{\mone}(y)} \frac{\nu(y)}{Sg(\mu)(y)} \comp \mu(x)&(Sg(\mu)(y)\neq 0)\\
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= &\frac{\nu(y)}{Sg(\mu)(y)} \comp \sum_{x \in g^{\mone}(y)} \mu(x)&(Sg(\mu)(y)\neq 0)\\
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= &\frac{\nu(y)}{Sg(\mu)(y)} \comp Sg(\mu)(y)&(Sg(\mu)(y)\neq 0)\\
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= &\mu(y)
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\end{align*}
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(If $Sg(\mu)(y) = 0$, then $\nu(y) = 0$, and the sum is $0$ as well, so the equality still holds.) \\
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