How to basically solve Integer programming problems?

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I learnt to solve the task below Linear Programmming is employed. I have tried studying texts to better understand what methods to employ out of the following:



$(A) Gomory's-cut$



$(B) Mixed-Gomory's-cut $



$(C) Branch-and-Bound $



But I am finding it difficult to comprehend any of the three and all the example I see are some how more complex and non related.Is there a way to simplify the problem below given the constraint is just $a,b,c,d,e,fin 4,2 $



beginalign
a+b+c+d+e+f &= 18, tag1 \
b+d &= 4, tag2 \
e+f &= 8, tag3
endalign



find $a,b,c,d,e,f$ ?










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  • 1




    we like to use the first letters of the alphabet for constants, and the last letters for variables
    – LinAlg
    Sep 1 at 13:15










  • Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
    – David M.
    Sep 1 at 13:48














up vote
0
down vote

favorite












I learnt to solve the task below Linear Programmming is employed. I have tried studying texts to better understand what methods to employ out of the following:



$(A) Gomory's-cut$



$(B) Mixed-Gomory's-cut $



$(C) Branch-and-Bound $



But I am finding it difficult to comprehend any of the three and all the example I see are some how more complex and non related.Is there a way to simplify the problem below given the constraint is just $a,b,c,d,e,fin 4,2 $



beginalign
a+b+c+d+e+f &= 18, tag1 \
b+d &= 4, tag2 \
e+f &= 8, tag3
endalign



find $a,b,c,d,e,f$ ?










share|cite|improve this question



















  • 1




    we like to use the first letters of the alphabet for constants, and the last letters for variables
    – LinAlg
    Sep 1 at 13:15










  • Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
    – David M.
    Sep 1 at 13:48












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I learnt to solve the task below Linear Programmming is employed. I have tried studying texts to better understand what methods to employ out of the following:



$(A) Gomory's-cut$



$(B) Mixed-Gomory's-cut $



$(C) Branch-and-Bound $



But I am finding it difficult to comprehend any of the three and all the example I see are some how more complex and non related.Is there a way to simplify the problem below given the constraint is just $a,b,c,d,e,fin 4,2 $



beginalign
a+b+c+d+e+f &= 18, tag1 \
b+d &= 4, tag2 \
e+f &= 8, tag3
endalign



find $a,b,c,d,e,f$ ?










share|cite|improve this question















I learnt to solve the task below Linear Programmming is employed. I have tried studying texts to better understand what methods to employ out of the following:



$(A) Gomory's-cut$



$(B) Mixed-Gomory's-cut $



$(C) Branch-and-Bound $



But I am finding it difficult to comprehend any of the three and all the example I see are some how more complex and non related.Is there a way to simplify the problem below given the constraint is just $a,b,c,d,e,fin 4,2 $



beginalign
a+b+c+d+e+f &= 18, tag1 \
b+d &= 4, tag2 \
e+f &= 8, tag3
endalign



find $a,b,c,d,e,f$ ?







abstract-algebra linear-programming integer-programming






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edited Sep 1 at 9:30

























asked Sep 1 at 9:08









LiNKeR

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  • 1




    we like to use the first letters of the alphabet for constants, and the last letters for variables
    – LinAlg
    Sep 1 at 13:15










  • Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
    – David M.
    Sep 1 at 13:48












  • 1




    we like to use the first letters of the alphabet for constants, and the last letters for variables
    – LinAlg
    Sep 1 at 13:15










  • Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
    – David M.
    Sep 1 at 13:48







1




1




we like to use the first letters of the alphabet for constants, and the last letters for variables
– LinAlg
Sep 1 at 13:15




we like to use the first letters of the alphabet for constants, and the last letters for variables
– LinAlg
Sep 1 at 13:15












Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
– David M.
Sep 1 at 13:48




Any integer program can be solved using (C) branch-and-bound (though it might be very slow—like, thousands of years slow). Any integer program can also be solved using (A) Gomory’s cut—if you add enough rounds of cuts, then you will find the optimal solution. This technique is ALSO very slow. As it turns out, if you combine (A) and (C) together, the result can be very fast. This is (very, very roughly) how IPs are solved today. Look up “branch and cut”.
– David M.
Sep 1 at 13:48










2 Answers
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If all the variable takes value from $2,4$.



The constraints reduces to



$$a+c=6$$



$$b+d=4 implies b=d=2$$



$$e+f=8 implies e=f=4$$



Hence $(a,c) = (4,2)$ or $(a,c)=(2,4)$.






share|cite|improve this answer




















  • How can an IP have "gaps" like the missing $3$ in $2,4$?
    – Rodrigo de Azevedo
    Sep 9 at 12:41










  • his constraint has gap isn't it? Did I misread his question?
    – Siong Thye Goh
    Sep 9 at 12:55










  • It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
    – Rodrigo de Azevedo
    Sep 9 at 12:59






  • 1




    well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
    – Siong Thye Goh
    Sep 9 at 13:01

















up vote
0
down vote













In your case, there is no need to advanced methods, unless you want to practice how to use them. If you only want to solve this specific problem you can do this:



$a+b+c+d+e+f=18$



is



$a+(b+d)+c+(e+f) =18$



so



$a+4+c+8=18$



so



$a+c=6$



since $a,b,c,d,e,fin 4,2 $



you can easily determine integer values for $a,c$ from the last equation.






share|cite|improve this answer




















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    2 Answers
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    2 Answers
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    up vote
    0
    down vote













    If all the variable takes value from $2,4$.



    The constraints reduces to



    $$a+c=6$$



    $$b+d=4 implies b=d=2$$



    $$e+f=8 implies e=f=4$$



    Hence $(a,c) = (4,2)$ or $(a,c)=(2,4)$.






    share|cite|improve this answer




















    • How can an IP have "gaps" like the missing $3$ in $2,4$?
      – Rodrigo de Azevedo
      Sep 9 at 12:41










    • his constraint has gap isn't it? Did I misread his question?
      – Siong Thye Goh
      Sep 9 at 12:55










    • It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
      – Rodrigo de Azevedo
      Sep 9 at 12:59






    • 1




      well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
      – Siong Thye Goh
      Sep 9 at 13:01














    up vote
    0
    down vote













    If all the variable takes value from $2,4$.



    The constraints reduces to



    $$a+c=6$$



    $$b+d=4 implies b=d=2$$



    $$e+f=8 implies e=f=4$$



    Hence $(a,c) = (4,2)$ or $(a,c)=(2,4)$.






    share|cite|improve this answer




















    • How can an IP have "gaps" like the missing $3$ in $2,4$?
      – Rodrigo de Azevedo
      Sep 9 at 12:41










    • his constraint has gap isn't it? Did I misread his question?
      – Siong Thye Goh
      Sep 9 at 12:55










    • It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
      – Rodrigo de Azevedo
      Sep 9 at 12:59






    • 1




      well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
      – Siong Thye Goh
      Sep 9 at 13:01












    up vote
    0
    down vote










    up vote
    0
    down vote









    If all the variable takes value from $2,4$.



    The constraints reduces to



    $$a+c=6$$



    $$b+d=4 implies b=d=2$$



    $$e+f=8 implies e=f=4$$



    Hence $(a,c) = (4,2)$ or $(a,c)=(2,4)$.






    share|cite|improve this answer












    If all the variable takes value from $2,4$.



    The constraints reduces to



    $$a+c=6$$



    $$b+d=4 implies b=d=2$$



    $$e+f=8 implies e=f=4$$



    Hence $(a,c) = (4,2)$ or $(a,c)=(2,4)$.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered Sep 1 at 9:16









    Siong Thye Goh

    81.9k1456104




    81.9k1456104











    • How can an IP have "gaps" like the missing $3$ in $2,4$?
      – Rodrigo de Azevedo
      Sep 9 at 12:41










    • his constraint has gap isn't it? Did I misread his question?
      – Siong Thye Goh
      Sep 9 at 12:55










    • It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
      – Rodrigo de Azevedo
      Sep 9 at 12:59






    • 1




      well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
      – Siong Thye Goh
      Sep 9 at 13:01
















    • How can an IP have "gaps" like the missing $3$ in $2,4$?
      – Rodrigo de Azevedo
      Sep 9 at 12:41










    • his constraint has gap isn't it? Did I misread his question?
      – Siong Thye Goh
      Sep 9 at 12:55










    • It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
      – Rodrigo de Azevedo
      Sep 9 at 12:59






    • 1




      well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
      – Siong Thye Goh
      Sep 9 at 13:01















    How can an IP have "gaps" like the missing $3$ in $2,4$?
    – Rodrigo de Azevedo
    Sep 9 at 12:41




    How can an IP have "gaps" like the missing $3$ in $2,4$?
    – Rodrigo de Azevedo
    Sep 9 at 12:41












    his constraint has gap isn't it? Did I misread his question?
    – Siong Thye Goh
    Sep 9 at 12:55




    his constraint has gap isn't it? Did I misread his question?
    – Siong Thye Goh
    Sep 9 at 12:55












    It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
    – Rodrigo de Azevedo
    Sep 9 at 12:59




    It has a gap. But is it still an IP? Is the feasible region of an IP the intersection of a convex polytope with $mathbb Z^n$? Or can it be the union of convex polytopes intersected with $mathbb Z^n$? Am I missing anything obvious?
    – Rodrigo de Azevedo
    Sep 9 at 12:59




    1




    1




    well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
    – Siong Thye Goh
    Sep 9 at 13:01




    well, that depends on the definiton of IP. For this particular question, we can divide all the variables by $2$ and the gap is gone.
    – Siong Thye Goh
    Sep 9 at 13:01










    up vote
    0
    down vote













    In your case, there is no need to advanced methods, unless you want to practice how to use them. If you only want to solve this specific problem you can do this:



    $a+b+c+d+e+f=18$



    is



    $a+(b+d)+c+(e+f) =18$



    so



    $a+4+c+8=18$



    so



    $a+c=6$



    since $a,b,c,d,e,fin 4,2 $



    you can easily determine integer values for $a,c$ from the last equation.






    share|cite|improve this answer
























      up vote
      0
      down vote













      In your case, there is no need to advanced methods, unless you want to practice how to use them. If you only want to solve this specific problem you can do this:



      $a+b+c+d+e+f=18$



      is



      $a+(b+d)+c+(e+f) =18$



      so



      $a+4+c+8=18$



      so



      $a+c=6$



      since $a,b,c,d,e,fin 4,2 $



      you can easily determine integer values for $a,c$ from the last equation.






      share|cite|improve this answer






















        up vote
        0
        down vote










        up vote
        0
        down vote









        In your case, there is no need to advanced methods, unless you want to practice how to use them. If you only want to solve this specific problem you can do this:



        $a+b+c+d+e+f=18$



        is



        $a+(b+d)+c+(e+f) =18$



        so



        $a+4+c+8=18$



        so



        $a+c=6$



        since $a,b,c,d,e,fin 4,2 $



        you can easily determine integer values for $a,c$ from the last equation.






        share|cite|improve this answer












        In your case, there is no need to advanced methods, unless you want to practice how to use them. If you only want to solve this specific problem you can do this:



        $a+b+c+d+e+f=18$



        is



        $a+(b+d)+c+(e+f) =18$



        so



        $a+4+c+8=18$



        so



        $a+c=6$



        since $a,b,c,d,e,fin 4,2 $



        you can easily determine integer values for $a,c$ from the last equation.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Sep 1 at 10:14









        NoChance

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