Magicwand started Masters degree in Operations Research

[TheBigH]

Yeah, the problem as stated doesn't make a lot of sense. If they meant to say the antibiotics can't be stored for more than a year, then it makes more sense. It becomes a question of balancing the $10 fixed ordering cost against the 20% holding cost. You don't want to order too often, or you'll be hit by the ordering cost. But you don't want to place large, infrequent orders because then you have to store many bottles and pay a large holding cost.

[cyclops]

Excel is free software?

[TheBigH]

No, excel is not free. But there are free alternatives like openoffice which do most of the same things. Contrary to popular belief, you don't even need a huge bushy Linux beard to use them.

[Bonobo]

[..] free alternatives like openoffice which do most of the same things. Contrary to popular belief, you don't even need a huge bushy Linux beard to use them.

OpenOffice is obsolete, AFAIK, and its successor is LibreOffice, available for free for OS X, Windows, and Linux.

/me strokes his huge bushy OS X beard

[tj86430]

OpenOffice is obsolete

StarOffice is even more obsolete, yet I use it every day on my Mac (which also has a paid-for MS Office)

[Bonobo]

OpenOffice is obsolete

StarOffice is even more obsolete, yet I use it every day on my Mac (which also has a paid-for MS Office)

Cool

(BTW I also have the commercial MS Office for OS X since for my job I sadly find that most other programs don’t know to handle buggy RTF files well, and I often need to to/from RTF)

Also, I didn’t intend to put TheBigH down or criticize their mention of OpenOffice, just wanted to mention that there’s a successor to it that’s actually being worked on

Greetings, Tom


<edit>

Trivia (should it not be “trivium” since it’s just one?): StarOffice was originally developed by Marco Börries and his company, Star Division, just 35 km to the East of my place, in Lüneburg, Germany

</edit>

[Magicwand]

i tried this on my own for past 7 hours..
i know i am wrong on decision tree.
can someone help me with decision tree?
for problem #5 i know that answer is indifferent about hiring and i dont know how they got that.
for problem #4 EVPI can not be less than EVSI so i assume that my tree is wrong.

thank you in advance.

Solved it on my own...took me 10 hours to solve.
yea..i suck at math.

[Magicwand]

no taker for previous question..

now i have simpler problem..(i think)

max v
st
v ≤ 1/2 x1 - x2 - x3

v ≤ -x1 + 1/2 x2 - x3

v ≤ -x1 -x2 + x3

x1 , x2 , x3 ≥ 0

how do i solve above LP?
It has been so long i forgot how to solve.
thank you in advance..

[emeraldemon]

Did your instructor suggest a method for solving linear programs? This problem is small enough that you should be able to test every vertex by hand, if that's all that's necessary.

[Magicwand]

Did your instructor suggest a method for solving linear programs? This problem is small enough that you should be able to test every vertex by hand, if that's all that's necessary.

can you guide me on how i can test every vertex?

i have similar example that is much simpler(with 2 variable) which was easily solved. one more variable throw me off.

[Magicwand]

Did your instructor suggest a method for solving linear programs? This problem is small enough that you should be able to test every vertex by hand, if that's all that's necessary.

can you guide me on how i can test every vertex?

i have similar example that is much simpler(with 2 variable) which was easily solved. one more variable throw me off.

I already have answer as [4/11,4/11,3/11] and try to figure how to derive that answer.
it shouldnt take this long for this simple problem but i am failing ....may be it is lack of sleep
i thought simple linear program i learned in college should do the trick...and done below using excel.

1/2 -1 -1 1
-1 1/2 -1 1
-1 -1 1 1

1 -2 -2 2
-1 1/2 -1 1
-1 -2 1 1

1 -2 -2 2
0 -1 1/2 -3 3
0 -4 -1 3

1 -2 -2 2
0 1 2 -2
0 -4 -1 3

1 0 2 -2
0 1 2 -2
0 0 7 -5

1 0 2 -2
0 1 2 -2
0 0 1 5/7

1 0 0 -3 3/7
0 1 0 -3 3/7
0 0 1 5/7

now that is not the answer i was looking for...
may be there is a mistake in my work or i am doing it totally wrong..
i would appreciate if someone can find my mistake.

v/r

[emeraldemon]

Looking more closely at your problem and what you call the solution, I think something is wrong, probably something is missing from your problem description. Was v defined in terms of x1,x2,x3 ? The values of x1,x2,x3 you suggest (if I'm interpreting you right) are [4/11,4/11,3/11], which gives v = -0.45455. But I can trivially come up with a better solution: x1 = x2 = x3 = 0, v = 0.

I don't really understand what you put with the grids of numbers, but it looks like maybe you are trying to solve a system of linear equations with Gaussian elimination? Linear programming is a different problem from solving linear systems, and it's harder. Was there a linear programming prerequisite for this class? You might not have the necessary background to do these, you may need to take some other class first.

[Magicwand]

Looking more closely at your problem and what you call the solution, I think something is wrong, probably something is missing from your problem description. Was v defined in terms of x1,x2,x3 ? The values of x1,x2,x3 you suggest (if I'm interpreting you right) are [4/11,4/11,3/11], which gives v = -0.45455. But I can trivially come up with a better solution: x1 = x2 = x3 = 0, v = 0.

I don't really understand what you put with the grids of numbers, but it looks like maybe you are trying to solve a system of linear equations with Gaussian elimination? Linear programming is a different problem from solving linear systems, and it's harder. Was there a linear programming prerequisite for this class? You might not have the necessary background to do these, you may need to take some other class first.

your trivial solution is not possible because this is LP for zero-sum game.
x1+x2+x3 have to equal to 1
if i solve that LP correctly answer would me 4/11,4/11,3/11
i want to know how.

i guess i will need to study linear programming all over again.
if you have any suggestion or even study materials so i can study... i would appreciate.
thank you for trying...

i have been at this for 3 nights straight...and no more strength left so i submitted it.

again thank you.

[Uzziel]

http://www.youtube.com/watch?v=3dUphCwFDJA

[Magicwand]

http://www.youtube.com/watch?v=3dUphCwFDJA

i saw couple of his video.... didnt learn anything new.
although i majored in math in college i realized that my understanding on math is so limited
i will attack that problem again after i finish STAT homework over the weekend...and another OR homework to stay ahead of the game.

Thank you all for your help.

i had enough of OR. now bash my brain with STAT