Sigma notation for iterating through number of members of a set with constant expression












1












$begingroup$


Say I have a graph G and I want to sum some constant C (like the minimum degree of the graph) for every vertex. Can I use the following notation?
$$sum_{x in V(G)}C $$



Is this an appropriate way to use sigma notation?
There is a similar question here Notation of the summation of a set of numbers
but it doesn't account for the fact that the expression could be a constant. A person I am working with questioned it and I couldn't find any resources where it is used in this manner. I don't see why it would be improper because you could have an expression like $sum_{i=1}^{n}C$.
Thank you










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  • $begingroup$
    It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
    $endgroup$
    – David K
    Dec 6 '18 at 22:03












  • $begingroup$
    We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
    $endgroup$
    – rachelhoward
    Dec 6 '18 at 22:09












  • $begingroup$
    OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
    $endgroup$
    – David K
    Dec 6 '18 at 22:16
















1












$begingroup$


Say I have a graph G and I want to sum some constant C (like the minimum degree of the graph) for every vertex. Can I use the following notation?
$$sum_{x in V(G)}C $$



Is this an appropriate way to use sigma notation?
There is a similar question here Notation of the summation of a set of numbers
but it doesn't account for the fact that the expression could be a constant. A person I am working with questioned it and I couldn't find any resources where it is used in this manner. I don't see why it would be improper because you could have an expression like $sum_{i=1}^{n}C$.
Thank you










share|cite|improve this question











$endgroup$












  • $begingroup$
    It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
    $endgroup$
    – David K
    Dec 6 '18 at 22:03












  • $begingroup$
    We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
    $endgroup$
    – rachelhoward
    Dec 6 '18 at 22:09












  • $begingroup$
    OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
    $endgroup$
    – David K
    Dec 6 '18 at 22:16














1












1








1





$begingroup$


Say I have a graph G and I want to sum some constant C (like the minimum degree of the graph) for every vertex. Can I use the following notation?
$$sum_{x in V(G)}C $$



Is this an appropriate way to use sigma notation?
There is a similar question here Notation of the summation of a set of numbers
but it doesn't account for the fact that the expression could be a constant. A person I am working with questioned it and I couldn't find any resources where it is used in this manner. I don't see why it would be improper because you could have an expression like $sum_{i=1}^{n}C$.
Thank you










share|cite|improve this question











$endgroup$




Say I have a graph G and I want to sum some constant C (like the minimum degree of the graph) for every vertex. Can I use the following notation?
$$sum_{x in V(G)}C $$



Is this an appropriate way to use sigma notation?
There is a similar question here Notation of the summation of a set of numbers
but it doesn't account for the fact that the expression could be a constant. A person I am working with questioned it and I couldn't find any resources where it is used in this manner. I don't see why it would be improper because you could have an expression like $sum_{i=1}^{n}C$.
Thank you







graph-theory summation proof-writing notation






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edited Dec 6 '18 at 22:09









Asaf Karagila

304k32430763




304k32430763










asked Dec 6 '18 at 21:59









rachelhowardrachelhoward

748




748












  • $begingroup$
    It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
    $endgroup$
    – David K
    Dec 6 '18 at 22:03












  • $begingroup$
    We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
    $endgroup$
    – rachelhoward
    Dec 6 '18 at 22:09












  • $begingroup$
    OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
    $endgroup$
    – David K
    Dec 6 '18 at 22:16


















  • $begingroup$
    It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
    $endgroup$
    – David K
    Dec 6 '18 at 22:03












  • $begingroup$
    We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
    $endgroup$
    – rachelhoward
    Dec 6 '18 at 22:09












  • $begingroup$
    OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
    $endgroup$
    – David K
    Dec 6 '18 at 22:16
















$begingroup$
It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
$endgroup$
– David K
Dec 6 '18 at 22:03






$begingroup$
It looks logically correct, but why wouldn't you just write $lvert V(G)rvert cdot C$?
$endgroup$
– David K
Dec 6 '18 at 22:03














$begingroup$
We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
$endgroup$
– rachelhoward
Dec 6 '18 at 22:09






$begingroup$
We do at some point in our proof. We actually use this notation and the equation that @gt6989b posted.
$endgroup$
– rachelhoward
Dec 6 '18 at 22:09














$begingroup$
OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
$endgroup$
– David K
Dec 6 '18 at 22:16




$begingroup$
OK, I could imagine your notation as an intermediate step while simplifying some other sum where you can separate out a constant term. Some authors would skip that intermediate step and go straight to the the multiplication but I think that is something you can decide not do to if you think it's helpful to show the intermediate step explicitly.
$endgroup$
– David K
Dec 6 '18 at 22:16










1 Answer
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$begingroup$

Indeed, you are correct, you can use $sum_{x in S} C$ for any set $S$ and constant $C$, and since $C$ does not depend on $x$, this simplifies to
$$
sum_{x in S} C = C cdot |S|,
$$

for any finite set $S$.






share|cite|improve this answer









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    1 Answer
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    1 Answer
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    $begingroup$

    Indeed, you are correct, you can use $sum_{x in S} C$ for any set $S$ and constant $C$, and since $C$ does not depend on $x$, this simplifies to
    $$
    sum_{x in S} C = C cdot |S|,
    $$

    for any finite set $S$.






    share|cite|improve this answer









    $endgroup$


















      2












      $begingroup$

      Indeed, you are correct, you can use $sum_{x in S} C$ for any set $S$ and constant $C$, and since $C$ does not depend on $x$, this simplifies to
      $$
      sum_{x in S} C = C cdot |S|,
      $$

      for any finite set $S$.






      share|cite|improve this answer









      $endgroup$
















        2












        2








        2





        $begingroup$

        Indeed, you are correct, you can use $sum_{x in S} C$ for any set $S$ and constant $C$, and since $C$ does not depend on $x$, this simplifies to
        $$
        sum_{x in S} C = C cdot |S|,
        $$

        for any finite set $S$.






        share|cite|improve this answer









        $endgroup$



        Indeed, you are correct, you can use $sum_{x in S} C$ for any set $S$ and constant $C$, and since $C$ does not depend on $x$, this simplifies to
        $$
        sum_{x in S} C = C cdot |S|,
        $$

        for any finite set $S$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 6 '18 at 22:06









        gt6989bgt6989b

        34k22455




        34k22455






























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