The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

D2 6th June 2013

Scroll to see replies

Reply 100
Avatar for smith50
smith50
6
Original post by mathswiz:)
Glad i could help :biggrin: I have done the dynamic programming question but the file is too big :frown:
e done the dynamic programming question but the file is too big :frown:




Oh that's a shame could you print screen your table i just want to compare tables please :biggrin:
Thanks,
Smith
Original post by smith50
e done the dynamic programming question but the file is too big :frown:





Oh that's a shame could you print screen your table i just want to compare tables please :biggrin:
Thanks,
Smith

Finally found a way to save them as pictures, hope they open :biggrin:
Dynamic programming1.png203.7KB
Dynamic programming 2.png71.8KB
Can someone possibly explain why the June 2009 paper has such low boundaries? 65/75 for an A*, and 73/75 for 100 UMS.

I just did it and it seemed ridiculously easy: no simplex at all and half of the dynamic programming is done for you. What gives? :s
Reply 103
Avatar for smith50
smith50
6
Original post by mathswiz:)
Oh that's a shame could you print screen your table i just want to compare tables please :biggrin:
Thanks,
Smith


Finally found a way to save them as pictures, hope they open :biggrin:

Thank you so much:wink:
Smith
Reply 104
Avatar for sl96
sl96
does anyone have a copy of definitions and jus writing stuff which is worth like a mark, i knw it hasnt come up recently but jus to be sfe :smile:
Reply 105
Avatar for smith50
smith50
6
Could you guys help me with this question D2 practise paper A.PNG please
Thanks,
Smith
Original post by smith50
Could you guys help me with this question D2 practise paper A.PNG please
Thanks,
Smith


Draw on the arc EJ with capacity 5, then look for how much spare capacity you can have going along this arc. Remember that everything going into an arc must equal everything coming out of the arc. You want to work out what is the maximum flow you can get through the arc EJ and then the same for the arc FH. :smile:


Posted from TSR Mobile
Original post by sl96
does anyone have a copy of definitions and jus writing stuff which is worth like a mark, i knw it hasnt come up recently but jus to be sfe :smile:


http://www.thestudentroom.co.uk/showthread.php?t=2013301 :smile:


Posted from TSR Mobile
Reply 108
Avatar for smith50
smith50
6
Could anyone help me on this :biggrin:
QP:Fw.PNG
MS:FW2.PNG
Thanks,
Smith
Guys can anyone tell me if we ever work with the classical problem?

I was doing a past paper and there was a short-cuts question. I got worried because I thought we weren't allowed to visit already used vertices, but it turns out it was the practical problem thankfully.

Is this always the case in D2 problems? Thanks :smile:
Reply 110
Avatar for smith50
smith50
6
Original post by Hamburglar
Guys can anyone tell me if we ever work with the classical problem?

I was doing a past paper and there was a short-cuts question. I got worried because I thought we weren't allowed to visit already used vertices, but it turns out it was the practical problem thankfully.

Is this always the case in D2 problems? Thanks :smile:


Use the classical problem for complete graphs satisfying the triangle inequality.
Smith
Original post by smith50
Use the classical problem for complete graphs satisfying the triangle inequality.
Smith


Oh, yeah but that is just finding least distances and stuff isn't it?

I'm mainly on about the three algorithms: nearest neighbour, RMST and MST + Shortcuts.

I think nearest neighbour is always classical because you always visit unique vertices.

I'm mainly worried about finding a spanning tree and shortcuts, because I hope that is always practical. If it was classical then that would be a bit of a mess...
Guys, just want to ask something real quick.

You know when you're working with the hungarian algorithm in a maximising problem, does it matter what number you pick to subtract the other elements from? I pick the largest number, but often mark schemes pick a number that is 1 larger and all my numbers are different by 1.

Does this matter? I'm worried it'll get marked wrong or something - thanks.

Also, is it just me or is the mock mark scheme a bit dodgy? :s The simplex question in particular
(edited 10 years ago)
Original post by Hamburglar
Guys, just want to ask something real quick.

You know when you're working with the hungarian algorithm in a maximising problem, does it matter what number you pick to subtract the other elements from? I pick the largest number, but often mark schemes pick a number that is 1 larger and all my numbers are different by 1.

Does this matter? I'm worried it'll get marked wrong or something - thanks.

Also, is it just me or is the mock mark scheme a bit dodgy? :s The simplex question in particular


For the Hungarian algorithm, I think you can choose any number, as long as it is at least as big as the largest number in the matrix. You basically want the initially largest number to be the smallest one, and the initially smallest one to be the largest. Do you usually get the correct numbers after you have reduced the rows and columns?
Original post by brittanna
For the Hungarian algorithm, I think you can choose any number, as long as it is at least as big as the largest number in the matrix. You basically want the initially largest number to be the smallest one, and the initially smallest one to be the largest. Do you usually get the correct numbers after you have reduced the rows and columns?


I think my final allocation was correct, and I feel as though my tables were correct too :smile: It's just the mark scheme seems to be a bit dodgy for the mock paper :s

But okay cool, thanks!

I was just wondering if you might be able to quickly answer this one too? When you're doing simplex and they say you should use the smallest positive value of theta for the pivot row - well, does this include zero as well?
Original post by Hamburglar
I think my final allocation was correct, and I feel as though my tables were correct too :smile: It's just the mark scheme seems to be a bit dodgy for the mock paper :s

But okay cool, thanks!

I was just wondering if you might be able to quickly answer this one too? When you're doing simplex and they say you should use the smallest positive value of theta for the pivot row - well, does this include zero as well?


I'm not sure. I always thought it had to be positive (so greater than zero), and the textbook also says positive as well. But then when you're doing game theory ones, you have to use a zero. So i'm guessing that you don't use zero, unless you're solving a game theory simplex question.
Original post by brittanna
I'm not sure. I always thought it had to be positive (so greater than zero), and the textbook also says positive as well. But then when you're doing game theory ones, you have to use a zero. So i'm guessing that you don't use zero, unless you're solving a game theory simplex question.


Ah I see in the book now, they do use zero in the game theory questions. Thanks

I would assume this means that you use zero in any other linear programming question too though? It's basically the same thing :s
Original post by smith50
Could anyone help me on this :biggrin:
QP:Fw.PNG
MS:FW2.PNG
Thanks,
Smith


Hello just wondering where these questions are from , the old edexcel d1? solomon?
Anybody have any advice on flow diagrams in terms of presentation?

Usually there's a question which says, start the procedure by entering values at these points. But then you have to use this diagram to find a flow and the original values get lost, in a giant sea of numbers and commas. How on earth is the examiner supposed to see what is going on? xD
Reply 119
Avatar for JayJay95
JayJay95
Original post by Hamburglar
Anybody have any advice on flow diagrams in terms of presentation?

Usually there's a question which says, start the procedure by entering values at these points. But then you have to use this diagram to find a flow and the original values get lost, in a giant sea of numbers and commas. How on earth is the examiner supposed to see what is going on? xD


Feel exactly the same way. When i use the flow augmenting procedure I have to change the flow values accordingly for every route i use and if i initaially had to label the diagram the original values are lost. Getting paranoid about this :s-smilie:

Posted from TSR Mobile

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you