How do you estimate the remaining degree distribution?












0












$begingroup$


Let $q_{j,k}$ be defined as the joint probability distribution of the remaining degrees of the two nodes at either end of a randomly chosen edge. Let $G=(V,E)$ be an undirected graph with nodes $V=(v_1,v_2,v_3,v_4)$, and edges $E=(e_1,e_2,e_3)$ where $e_1=(v_1,v_2)$,$e_2=(v_2,v_3)$ and $e_3=(v_3,v_4)$.



In other words a graph with the structure




o-o-o-o




Am I correct in assuming that $q_{j,k}$ can be calculated with the formula



$q_{j,k} = mu(j,k)frac{n(j,k)}{2|E|}$



where $n(j,k)$ is the number of edges connecting nodes with remaining degrees $j$ and $k$, and $mu(j,k) = begin{cases} 2 text{ if } j = k \ 1 text{ else} end{cases}$. In which case an estimation of $q_{j,k}$ based on graph $G$ would be the following:



$q_{0,1} = q_{1,0} = 1frac{2}{6} \ q_{1,1} = 2frac{1}{6}$



As you can see, all probabilities sum to 1. However online there is a slide show (page 9) that shows that the joint degree distribution, which is closely related to the remaining degree distribution, is apparently supposed to be calculated with a similar formula except $j$ and $k$ are now degrees rather than remaining degrees (subtract 1), and $mu(j,k) = begin{cases} 1 text{ if } j = k \ 2 text{ else} end{cases}$.



With the formula suggested in the slide show the calculation of $q_{j,k}$ wouldn't work even if $j$ and $k$ were degrees rather than remaining degrees because the probabilities wouldn't add up to 1. So am I missing something or has a mistake been made in those slides?










share|cite|improve this question











$endgroup$

















    0












    $begingroup$


    Let $q_{j,k}$ be defined as the joint probability distribution of the remaining degrees of the two nodes at either end of a randomly chosen edge. Let $G=(V,E)$ be an undirected graph with nodes $V=(v_1,v_2,v_3,v_4)$, and edges $E=(e_1,e_2,e_3)$ where $e_1=(v_1,v_2)$,$e_2=(v_2,v_3)$ and $e_3=(v_3,v_4)$.



    In other words a graph with the structure




    o-o-o-o




    Am I correct in assuming that $q_{j,k}$ can be calculated with the formula



    $q_{j,k} = mu(j,k)frac{n(j,k)}{2|E|}$



    where $n(j,k)$ is the number of edges connecting nodes with remaining degrees $j$ and $k$, and $mu(j,k) = begin{cases} 2 text{ if } j = k \ 1 text{ else} end{cases}$. In which case an estimation of $q_{j,k}$ based on graph $G$ would be the following:



    $q_{0,1} = q_{1,0} = 1frac{2}{6} \ q_{1,1} = 2frac{1}{6}$



    As you can see, all probabilities sum to 1. However online there is a slide show (page 9) that shows that the joint degree distribution, which is closely related to the remaining degree distribution, is apparently supposed to be calculated with a similar formula except $j$ and $k$ are now degrees rather than remaining degrees (subtract 1), and $mu(j,k) = begin{cases} 1 text{ if } j = k \ 2 text{ else} end{cases}$.



    With the formula suggested in the slide show the calculation of $q_{j,k}$ wouldn't work even if $j$ and $k$ were degrees rather than remaining degrees because the probabilities wouldn't add up to 1. So am I missing something or has a mistake been made in those slides?










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Let $q_{j,k}$ be defined as the joint probability distribution of the remaining degrees of the two nodes at either end of a randomly chosen edge. Let $G=(V,E)$ be an undirected graph with nodes $V=(v_1,v_2,v_3,v_4)$, and edges $E=(e_1,e_2,e_3)$ where $e_1=(v_1,v_2)$,$e_2=(v_2,v_3)$ and $e_3=(v_3,v_4)$.



      In other words a graph with the structure




      o-o-o-o




      Am I correct in assuming that $q_{j,k}$ can be calculated with the formula



      $q_{j,k} = mu(j,k)frac{n(j,k)}{2|E|}$



      where $n(j,k)$ is the number of edges connecting nodes with remaining degrees $j$ and $k$, and $mu(j,k) = begin{cases} 2 text{ if } j = k \ 1 text{ else} end{cases}$. In which case an estimation of $q_{j,k}$ based on graph $G$ would be the following:



      $q_{0,1} = q_{1,0} = 1frac{2}{6} \ q_{1,1} = 2frac{1}{6}$



      As you can see, all probabilities sum to 1. However online there is a slide show (page 9) that shows that the joint degree distribution, which is closely related to the remaining degree distribution, is apparently supposed to be calculated with a similar formula except $j$ and $k$ are now degrees rather than remaining degrees (subtract 1), and $mu(j,k) = begin{cases} 1 text{ if } j = k \ 2 text{ else} end{cases}$.



      With the formula suggested in the slide show the calculation of $q_{j,k}$ wouldn't work even if $j$ and $k$ were degrees rather than remaining degrees because the probabilities wouldn't add up to 1. So am I missing something or has a mistake been made in those slides?










      share|cite|improve this question











      $endgroup$




      Let $q_{j,k}$ be defined as the joint probability distribution of the remaining degrees of the two nodes at either end of a randomly chosen edge. Let $G=(V,E)$ be an undirected graph with nodes $V=(v_1,v_2,v_3,v_4)$, and edges $E=(e_1,e_2,e_3)$ where $e_1=(v_1,v_2)$,$e_2=(v_2,v_3)$ and $e_3=(v_3,v_4)$.



      In other words a graph with the structure




      o-o-o-o




      Am I correct in assuming that $q_{j,k}$ can be calculated with the formula



      $q_{j,k} = mu(j,k)frac{n(j,k)}{2|E|}$



      where $n(j,k)$ is the number of edges connecting nodes with remaining degrees $j$ and $k$, and $mu(j,k) = begin{cases} 2 text{ if } j = k \ 1 text{ else} end{cases}$. In which case an estimation of $q_{j,k}$ based on graph $G$ would be the following:



      $q_{0,1} = q_{1,0} = 1frac{2}{6} \ q_{1,1} = 2frac{1}{6}$



      As you can see, all probabilities sum to 1. However online there is a slide show (page 9) that shows that the joint degree distribution, which is closely related to the remaining degree distribution, is apparently supposed to be calculated with a similar formula except $j$ and $k$ are now degrees rather than remaining degrees (subtract 1), and $mu(j,k) = begin{cases} 1 text{ if } j = k \ 2 text{ else} end{cases}$.



      With the formula suggested in the slide show the calculation of $q_{j,k}$ wouldn't work even if $j$ and $k$ were degrees rather than remaining degrees because the probabilities wouldn't add up to 1. So am I missing something or has a mistake been made in those slides?







      probability probability-distributions graph-theory estimation network






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 12 at 21:19







      Jonathan

















      asked Jan 12 at 20:38









      JonathanJonathan

      1957




      1957






















          1 Answer
          1






          active

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          2












          $begingroup$

          You are right - either way, no matter if you want the joint degree distribution or the remaining degree distribution, you want the diagonal terms $q_{j,j}$ to be the ones multiplied by $2$, not the other ones.



          We sample from either distribution by picking an edge, then picking which endpoint is first and which is second. If the degrees of its endpoints are both $j$, then the edge contributes to $q_{j,j}$ no matter what. If the degrees of its endpoints are $j ne k$, then the edge has a $frac12$ chance of contributing to $q_{j,k}$ and a $frac12$ chance of contributing to $q_{k,j}$.



          You might write down the same function as $frac{m(j,k)}{nu(j,k) cdot m}$ where $m$ is the number of edges and $nu(j,k) = begin{cases}1 & j=k \ 2 & text{else}end{cases}$, and it's possible that here is where the mistake comes from.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
            $endgroup$
            – Jonathan
            Jan 13 at 2:04








          • 1




            $begingroup$
            Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:12






          • 1




            $begingroup$
            Anyway, you're completely right that this has to be a mistake.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:16










          • $begingroup$
            Thanks so much for the quick response, very helpful answer.
            $endgroup$
            – Jonathan
            Jan 13 at 2:23











          Your Answer





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          2












          $begingroup$

          You are right - either way, no matter if you want the joint degree distribution or the remaining degree distribution, you want the diagonal terms $q_{j,j}$ to be the ones multiplied by $2$, not the other ones.



          We sample from either distribution by picking an edge, then picking which endpoint is first and which is second. If the degrees of its endpoints are both $j$, then the edge contributes to $q_{j,j}$ no matter what. If the degrees of its endpoints are $j ne k$, then the edge has a $frac12$ chance of contributing to $q_{j,k}$ and a $frac12$ chance of contributing to $q_{k,j}$.



          You might write down the same function as $frac{m(j,k)}{nu(j,k) cdot m}$ where $m$ is the number of edges and $nu(j,k) = begin{cases}1 & j=k \ 2 & text{else}end{cases}$, and it's possible that here is where the mistake comes from.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
            $endgroup$
            – Jonathan
            Jan 13 at 2:04








          • 1




            $begingroup$
            Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:12






          • 1




            $begingroup$
            Anyway, you're completely right that this has to be a mistake.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:16










          • $begingroup$
            Thanks so much for the quick response, very helpful answer.
            $endgroup$
            – Jonathan
            Jan 13 at 2:23
















          2












          $begingroup$

          You are right - either way, no matter if you want the joint degree distribution or the remaining degree distribution, you want the diagonal terms $q_{j,j}$ to be the ones multiplied by $2$, not the other ones.



          We sample from either distribution by picking an edge, then picking which endpoint is first and which is second. If the degrees of its endpoints are both $j$, then the edge contributes to $q_{j,j}$ no matter what. If the degrees of its endpoints are $j ne k$, then the edge has a $frac12$ chance of contributing to $q_{j,k}$ and a $frac12$ chance of contributing to $q_{k,j}$.



          You might write down the same function as $frac{m(j,k)}{nu(j,k) cdot m}$ where $m$ is the number of edges and $nu(j,k) = begin{cases}1 & j=k \ 2 & text{else}end{cases}$, and it's possible that here is where the mistake comes from.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
            $endgroup$
            – Jonathan
            Jan 13 at 2:04








          • 1




            $begingroup$
            Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:12






          • 1




            $begingroup$
            Anyway, you're completely right that this has to be a mistake.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:16










          • $begingroup$
            Thanks so much for the quick response, very helpful answer.
            $endgroup$
            – Jonathan
            Jan 13 at 2:23














          2












          2








          2





          $begingroup$

          You are right - either way, no matter if you want the joint degree distribution or the remaining degree distribution, you want the diagonal terms $q_{j,j}$ to be the ones multiplied by $2$, not the other ones.



          We sample from either distribution by picking an edge, then picking which endpoint is first and which is second. If the degrees of its endpoints are both $j$, then the edge contributes to $q_{j,j}$ no matter what. If the degrees of its endpoints are $j ne k$, then the edge has a $frac12$ chance of contributing to $q_{j,k}$ and a $frac12$ chance of contributing to $q_{k,j}$.



          You might write down the same function as $frac{m(j,k)}{nu(j,k) cdot m}$ where $m$ is the number of edges and $nu(j,k) = begin{cases}1 & j=k \ 2 & text{else}end{cases}$, and it's possible that here is where the mistake comes from.






          share|cite|improve this answer











          $endgroup$



          You are right - either way, no matter if you want the joint degree distribution or the remaining degree distribution, you want the diagonal terms $q_{j,j}$ to be the ones multiplied by $2$, not the other ones.



          We sample from either distribution by picking an edge, then picking which endpoint is first and which is second. If the degrees of its endpoints are both $j$, then the edge contributes to $q_{j,j}$ no matter what. If the degrees of its endpoints are $j ne k$, then the edge has a $frac12$ chance of contributing to $q_{j,k}$ and a $frac12$ chance of contributing to $q_{k,j}$.



          You might write down the same function as $frac{m(j,k)}{nu(j,k) cdot m}$ where $m$ is the number of edges and $nu(j,k) = begin{cases}1 & j=k \ 2 & text{else}end{cases}$, and it's possible that here is where the mistake comes from.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 13 at 2:16

























          answered Jan 13 at 0:04









          Misha LavrovMisha Lavrov

          47.7k657107




          47.7k657107












          • $begingroup$
            Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
            $endgroup$
            – Jonathan
            Jan 13 at 2:04








          • 1




            $begingroup$
            Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:12






          • 1




            $begingroup$
            Anyway, you're completely right that this has to be a mistake.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:16










          • $begingroup$
            Thanks so much for the quick response, very helpful answer.
            $endgroup$
            – Jonathan
            Jan 13 at 2:23


















          • $begingroup$
            Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
            $endgroup$
            – Jonathan
            Jan 13 at 2:04








          • 1




            $begingroup$
            Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:12






          • 1




            $begingroup$
            Anyway, you're completely right that this has to be a mistake.
            $endgroup$
            – Misha Lavrov
            Jan 13 at 2:16










          • $begingroup$
            Thanks so much for the quick response, very helpful answer.
            $endgroup$
            – Jonathan
            Jan 13 at 2:23
















          $begingroup$
          Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
          $endgroup$
          – Jonathan
          Jan 13 at 2:04






          $begingroup$
          Thanks very much for the answer but unfortunately this does not answer my question. I am already aware of how the two distributions are related. I wanted to make sure my formula for calculating the distribution was correct. The source of confusion was about function $mu(j,k)$. To reiterate, in the learning material I linked to, the $mu(j,k)$ function appears to be wrong precisely because using their version of the function causes the probabilities to not add up. But mine appears to be right. So I just wanted to clarify if I'm right or the learning material is right and I've missed something.
          $endgroup$
          – Jonathan
          Jan 13 at 2:04






          1




          1




          $begingroup$
          Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
          $endgroup$
          – Misha Lavrov
          Jan 13 at 2:12




          $begingroup$
          Oh, I see - I missed completely the fact that in your second definition of $mu$, the $1$ and $2$ are switched.
          $endgroup$
          – Misha Lavrov
          Jan 13 at 2:12




          1




          1




          $begingroup$
          Anyway, you're completely right that this has to be a mistake.
          $endgroup$
          – Misha Lavrov
          Jan 13 at 2:16




          $begingroup$
          Anyway, you're completely right that this has to be a mistake.
          $endgroup$
          – Misha Lavrov
          Jan 13 at 2:16












          $begingroup$
          Thanks so much for the quick response, very helpful answer.
          $endgroup$
          – Jonathan
          Jan 13 at 2:23




          $begingroup$
          Thanks so much for the quick response, very helpful answer.
          $endgroup$
          – Jonathan
          Jan 13 at 2:23


















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