Degrees in Monomials












1












$begingroup$


I am looking over the Joux-Vitse algorithm paper whereby they present an algorithm that seems to outperform exhaustive search and some state-of-the-art algorithms. However, it only works with polynomials in $B[X_0,...,X_{n-1}]$ whereby $B$ stands for boolean, meaning that we are working in $GF(2)$.



One of the steps is to calculate the total degree of a polynomial in $X_{k},...,X_{n-1}$. This is where my doubts arise.



Consider the following polynomial



$f = x_0x_4 + x_1x_4 + x_3$



whereby $n$, the number of variables = 5 and $k = 3$. This means that we want to calculate the total degree of $f$ in $x_3, x_4, x_5$.



My issue is that I am not sure whether the total degree of $f$ in these variables is equal to 3 (since $x_4$ occurs twice and $x_3$ occurs once) or whether it is 2 since the maximum degree of $x_4$ is 1 and $x_3$ is also 1.



My question boils down to: how would I count the total degree of a monomial in a specific set of variables?



Thank you for the help!










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    1












    $begingroup$


    I am looking over the Joux-Vitse algorithm paper whereby they present an algorithm that seems to outperform exhaustive search and some state-of-the-art algorithms. However, it only works with polynomials in $B[X_0,...,X_{n-1}]$ whereby $B$ stands for boolean, meaning that we are working in $GF(2)$.



    One of the steps is to calculate the total degree of a polynomial in $X_{k},...,X_{n-1}$. This is where my doubts arise.



    Consider the following polynomial



    $f = x_0x_4 + x_1x_4 + x_3$



    whereby $n$, the number of variables = 5 and $k = 3$. This means that we want to calculate the total degree of $f$ in $x_3, x_4, x_5$.



    My issue is that I am not sure whether the total degree of $f$ in these variables is equal to 3 (since $x_4$ occurs twice and $x_3$ occurs once) or whether it is 2 since the maximum degree of $x_4$ is 1 and $x_3$ is also 1.



    My question boils down to: how would I count the total degree of a monomial in a specific set of variables?



    Thank you for the help!










    share|cite|improve this question











    $endgroup$















      1












      1








      1


      0



      $begingroup$


      I am looking over the Joux-Vitse algorithm paper whereby they present an algorithm that seems to outperform exhaustive search and some state-of-the-art algorithms. However, it only works with polynomials in $B[X_0,...,X_{n-1}]$ whereby $B$ stands for boolean, meaning that we are working in $GF(2)$.



      One of the steps is to calculate the total degree of a polynomial in $X_{k},...,X_{n-1}$. This is where my doubts arise.



      Consider the following polynomial



      $f = x_0x_4 + x_1x_4 + x_3$



      whereby $n$, the number of variables = 5 and $k = 3$. This means that we want to calculate the total degree of $f$ in $x_3, x_4, x_5$.



      My issue is that I am not sure whether the total degree of $f$ in these variables is equal to 3 (since $x_4$ occurs twice and $x_3$ occurs once) or whether it is 2 since the maximum degree of $x_4$ is 1 and $x_3$ is also 1.



      My question boils down to: how would I count the total degree of a monomial in a specific set of variables?



      Thank you for the help!










      share|cite|improve this question











      $endgroup$




      I am looking over the Joux-Vitse algorithm paper whereby they present an algorithm that seems to outperform exhaustive search and some state-of-the-art algorithms. However, it only works with polynomials in $B[X_0,...,X_{n-1}]$ whereby $B$ stands for boolean, meaning that we are working in $GF(2)$.



      One of the steps is to calculate the total degree of a polynomial in $X_{k},...,X_{n-1}$. This is where my doubts arise.



      Consider the following polynomial



      $f = x_0x_4 + x_1x_4 + x_3$



      whereby $n$, the number of variables = 5 and $k = 3$. This means that we want to calculate the total degree of $f$ in $x_3, x_4, x_5$.



      My issue is that I am not sure whether the total degree of $f$ in these variables is equal to 3 (since $x_4$ occurs twice and $x_3$ occurs once) or whether it is 2 since the maximum degree of $x_4$ is 1 and $x_3$ is also 1.



      My question boils down to: how would I count the total degree of a monomial in a specific set of variables?



      Thank you for the help!







      abstract-algebra polynomials commutative-algebra finite-fields






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      edited Dec 3 '18 at 20:41









      user26857

      39.3k124183




      39.3k124183










      asked Dec 3 '18 at 19:04









      João DuarteJoão Duarte

      63




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          1 Answer
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          1












          $begingroup$

          The degree of the polynomial you've given in the variables you care about, $x_3,x_4,x_5$ is 1. Though the presence of $x_0$ is confusing given that you indicate variable indices start at 1 earlier.



          Here's a slightly more general definition of degree for polynomials that should be helpful to you.



          Given a weighting of the variables, which assigns to each variable $x_i$ a (lets say nonnegative) integer, $|x_i|$, (notation more or less unrelated to absolute values) called its weight. The degree of a monomial $prod_i x_i^{k_i}$ with respect to this weighting is $sum_i k_i|x_i|$. Then we define the degree of a polynomial with respect to this weighting to be the maximum degree of the monomials in the polynomial.



          Hence in your situation, you have $|x_0|=|x_1|=|x_2|=0$ and $|x_3|=|x_4|=|x_5|=1$. Thus the degree of $x_0x_4+x_1x_4+x_3$ is
          $$max {0+1,0+1,1}=1.$$



          Edit



          To be a bit more clear, if $S$ is a set of indices indicating variables that you care about, then you have a weighting of the variables with $|x_i|=0$ if $inotin S$ and $|x_i|=1$ if $iin S$. Then the degree of a monomial/polynomial in these variables with respect to this weighting is calculated as above.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:35












          • $begingroup$
            However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:41











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          $begingroup$

          The degree of the polynomial you've given in the variables you care about, $x_3,x_4,x_5$ is 1. Though the presence of $x_0$ is confusing given that you indicate variable indices start at 1 earlier.



          Here's a slightly more general definition of degree for polynomials that should be helpful to you.



          Given a weighting of the variables, which assigns to each variable $x_i$ a (lets say nonnegative) integer, $|x_i|$, (notation more or less unrelated to absolute values) called its weight. The degree of a monomial $prod_i x_i^{k_i}$ with respect to this weighting is $sum_i k_i|x_i|$. Then we define the degree of a polynomial with respect to this weighting to be the maximum degree of the monomials in the polynomial.



          Hence in your situation, you have $|x_0|=|x_1|=|x_2|=0$ and $|x_3|=|x_4|=|x_5|=1$. Thus the degree of $x_0x_4+x_1x_4+x_3$ is
          $$max {0+1,0+1,1}=1.$$



          Edit



          To be a bit more clear, if $S$ is a set of indices indicating variables that you care about, then you have a weighting of the variables with $|x_i|=0$ if $inotin S$ and $|x_i|=1$ if $iin S$. Then the degree of a monomial/polynomial in these variables with respect to this weighting is calculated as above.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:35












          • $begingroup$
            However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:41
















          1












          $begingroup$

          The degree of the polynomial you've given in the variables you care about, $x_3,x_4,x_5$ is 1. Though the presence of $x_0$ is confusing given that you indicate variable indices start at 1 earlier.



          Here's a slightly more general definition of degree for polynomials that should be helpful to you.



          Given a weighting of the variables, which assigns to each variable $x_i$ a (lets say nonnegative) integer, $|x_i|$, (notation more or less unrelated to absolute values) called its weight. The degree of a monomial $prod_i x_i^{k_i}$ with respect to this weighting is $sum_i k_i|x_i|$. Then we define the degree of a polynomial with respect to this weighting to be the maximum degree of the monomials in the polynomial.



          Hence in your situation, you have $|x_0|=|x_1|=|x_2|=0$ and $|x_3|=|x_4|=|x_5|=1$. Thus the degree of $x_0x_4+x_1x_4+x_3$ is
          $$max {0+1,0+1,1}=1.$$



          Edit



          To be a bit more clear, if $S$ is a set of indices indicating variables that you care about, then you have a weighting of the variables with $|x_i|=0$ if $inotin S$ and $|x_i|=1$ if $iin S$. Then the degree of a monomial/polynomial in these variables with respect to this weighting is calculated as above.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:35












          • $begingroup$
            However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:41














          1












          1








          1





          $begingroup$

          The degree of the polynomial you've given in the variables you care about, $x_3,x_4,x_5$ is 1. Though the presence of $x_0$ is confusing given that you indicate variable indices start at 1 earlier.



          Here's a slightly more general definition of degree for polynomials that should be helpful to you.



          Given a weighting of the variables, which assigns to each variable $x_i$ a (lets say nonnegative) integer, $|x_i|$, (notation more or less unrelated to absolute values) called its weight. The degree of a monomial $prod_i x_i^{k_i}$ with respect to this weighting is $sum_i k_i|x_i|$. Then we define the degree of a polynomial with respect to this weighting to be the maximum degree of the monomials in the polynomial.



          Hence in your situation, you have $|x_0|=|x_1|=|x_2|=0$ and $|x_3|=|x_4|=|x_5|=1$. Thus the degree of $x_0x_4+x_1x_4+x_3$ is
          $$max {0+1,0+1,1}=1.$$



          Edit



          To be a bit more clear, if $S$ is a set of indices indicating variables that you care about, then you have a weighting of the variables with $|x_i|=0$ if $inotin S$ and $|x_i|=1$ if $iin S$. Then the degree of a monomial/polynomial in these variables with respect to this weighting is calculated as above.






          share|cite|improve this answer









          $endgroup$



          The degree of the polynomial you've given in the variables you care about, $x_3,x_4,x_5$ is 1. Though the presence of $x_0$ is confusing given that you indicate variable indices start at 1 earlier.



          Here's a slightly more general definition of degree for polynomials that should be helpful to you.



          Given a weighting of the variables, which assigns to each variable $x_i$ a (lets say nonnegative) integer, $|x_i|$, (notation more or less unrelated to absolute values) called its weight. The degree of a monomial $prod_i x_i^{k_i}$ with respect to this weighting is $sum_i k_i|x_i|$. Then we define the degree of a polynomial with respect to this weighting to be the maximum degree of the monomials in the polynomial.



          Hence in your situation, you have $|x_0|=|x_1|=|x_2|=0$ and $|x_3|=|x_4|=|x_5|=1$. Thus the degree of $x_0x_4+x_1x_4+x_3$ is
          $$max {0+1,0+1,1}=1.$$



          Edit



          To be a bit more clear, if $S$ is a set of indices indicating variables that you care about, then you have a weighting of the variables with $|x_i|=0$ if $inotin S$ and $|x_i|=1$ if $iin S$. Then the degree of a monomial/polynomial in these variables with respect to this weighting is calculated as above.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 3 '18 at 19:31









          jgonjgon

          13.5k22041




          13.5k22041












          • $begingroup$
            Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:35












          • $begingroup$
            However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:41


















          • $begingroup$
            Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:35












          • $begingroup$
            However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
            $endgroup$
            – João Duarte
            Dec 3 '18 at 20:41
















          $begingroup$
          Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
          $endgroup$
          – João Duarte
          Dec 3 '18 at 20:35






          $begingroup$
          Hi! That makes sense, thank you very much. And yes, sorry, I meant to write $X_0$ till $X_{n-1}$.
          $endgroup$
          – João Duarte
          Dec 3 '18 at 20:35














          $begingroup$
          However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
          $endgroup$
          – João Duarte
          Dec 3 '18 at 20:41




          $begingroup$
          However, this does seem weird in the context of the paper, so maybe they are looking for a different way of doing things. I'll just have to have another look
          $endgroup$
          – João Duarte
          Dec 3 '18 at 20:41


















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