x Turn on thread page Beta
 You are Here: Home >< Maths

# D2 6th June 2013 watch

1. Actually so worried for this exam! Has anyone got any revision tips for it? Not many people seem to be sitting it for some reason?
2. Hooray someone else sitting this exam! lol we're a rare breed out here
3. (Original post by Lilmzbest)
Hooray someone else sitting this exam! lol we're a rare breed out here
Definitely, unfortunately :/ how've you been preparing for it? The simplex is just horrendous

Posted from TSR Mobile
4. (Original post by kashagupta)
Definitely, unfortunately :/ how've you been preparing for it? The simplex is just horrendous

Posted from TSR Mobile
Aah simplex, it just makes you want to cry tbh i just practiced simplex a lot and i'm fairly confident in it now, i just make sure to double check all my answers as soon as i get to the row operations bit, like most of D2 i find that you are more likely to lose marks from wrong calculation than by not knowing what you're doing

I'm just getting lots of practice (doing all the exercises in the book) and trying to keep the algorithms fresh in my head, so the exam should be okay i hope
5. Hey, it's nice to find other people doing D2; I'm sitting this exam as well. Is your school making you guys sit this exam or are you guys self-teaching it?
6. (Original post by Epic Flawless)
Hey, it's nice to find other people doing D2; I'm sitting this exam as well. Is your school making you guys sit this exam or are you guys self-teaching it?
Nah D2 is part of my further maths A2 so my whole class is doing it i personally love it but literally the rest of the class hates it
7. How do you know the inequality signs for this? I know which 2 are best upper/lower bound but why the less than or equal to inequality sign for upper bound and not lower bound?????
Attached Images

8. (Original post by Knoyle quiah)
How do you know the inequality signs for this? I know which 2 are best upper/lower bound but why the less than or equal to inequality sign for upper bound and not lower bound?????

The thing to understand is that when you calculated the upper bound you calculated and actual route so it is a feasible solution

The method to find the lower bound simply gives a value for the lower bound, it doesn't actually give a feasible solution, if you draw out the network you got after adding back C in part (e) of the question then you'll notice that it doesn't actually give you a feasible route, therefore the inequality sign is just a more than sign

N.B If you delete a vertex and then add it back in and you get a tour, then this is the optimal solution ... but that doesn't usually happen
9. (Original post by Lilmzbest)
The thing to understand is that when you calculated the upper bound you calculated and actual route so it is a feasible solution

The method to find the lower bound simply gives a value for the lower bound, it doesn't actually give a feasible solution, if you draw out the network you got after adding back C in part (e) of the question then you'll notice that it doesn't actually give you a feasible route, therefore the inequality sign is just a more than sign

N.B If you delete a vertex and then add it back in and you get a tour, then this is the optimal solution ... but that doesn't usually happen
Ahh that makes sense, I understand, thank you , how did you know this?
10. (Original post by Knoyle quiah)
Ahh that makes sense, I understand, thank you , how did you know this?
Oh ... i guess i just figured it out, lol D2 is the only maths module i actually understand
11. How do i find the minimum cut on this diagram (capacitated) ???
Attached Images

12. (Original post by Knoyle quiah)
How do i find the minimum cut on this diagram (capacitated) ???
Afaik the minimum cut is one that goes through only saturated arcs (conditions are p193 in the textbook). Therefore you need the flows to see which cut is a minimum
13. (Original post by Lilmzbest)
Afaik the minimum cut is one that goes through only saturated arcs (conditions are p193 in the textbook). Therefore you need the flows to see which cut is a minimum
It can also go through empty arcs as well but these would not contribute to the value of the min cut (as they are 'out of cut').
14. (Original post by Epic Flawless)
It can also go through empty arcs as well but these would not contribute to the value of the min cut (as they are 'out of cut').
Lol yeah i know just need to get the flow values first, but thanks for pointing that out, its something that people often miss
15. Oh LORD! i haven't started D2 yet... so many exams T.T
16. (Original post by bonjour04)
Oh LORD! i haven't started D2 yet... so many exams T.T
I wouldn't panic if I were you, just start now, it's fairly easy to get your head around and there's still 3 weeks left
17. (Original post by Lilmzbest)
I wouldn't panic if I were you, just start now, it's fairly easy to get your head around and there's still 3 weeks left
Aha hopefully. Just realised we have game theory too *face palm*
18. Can someone please explain to me the answer to Edexcel D2 examination style paper Q 2e?

Is there any flow-augmenting route?

Thank you
19. (Original post by imasha.sj)
Can someone please explain to me the answer to Edexcel D2 examination style paper Q 2e?

Is there any flow-augmenting route?

Thank you
I'm afraid i have no idea which paper that is...is there a link to it, or could you scan the question in?
20. (Original post by imasha.sj)
Can someone please explain to me the answer to Edexcel D2 examination style paper Q 2e?

Is there any flow-augmenting route?

Thank you
Oh you meant the one in the book! My bad i got SCBEDT, its a confusing one because both arcs BC and DE have backflow

Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 11, 2013
Today on TSR

### Loughborough better than Cambridge

Loughborough at number one

Poll
Useful resources

## Make your revision easier

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE