D2 6th June 2013

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

A revision thread I started last year. Contains lots of papers etc.

Here is a sheet of definitions; however, don't forget any definition from D1 'could' be asked.

absolutely hammer the 3 different LP questions; Allocation, Transportation, Game theory. One is guaranteed to come up and it is gift marks if revised properly.

Why would player Y never play Y1??? says on mark scheme it shouldnt, im trying to do part B of question

Not through domination. So it must be obvious from well graph. Lines l2 and l3 will always be the best option for Y


Posted from TSR Mobile

Sorry I dont understand, do I draw another graph for player Y? i have attached the mark scheme, i couldnt find because of domination so didnt know why else

The required intersection for X's optimal strategy is Y2 = Y3.
Therefore, if X is playing his optimal mixed strategy, Y should never play Y1.

Game theory looks scary but actually isn't, it's just about learning how to set out a mixed strategy answer and then just practicing

Sorry I dont understand, do I draw another graph for player Y? i have attached the mark scheme, i couldnt find because of domination so didnt know why else

it is because if player X? is playing safe then his best option is to pick the highest point of the lowest lines, which in this case is where Y2 and Y3 meet. Therefore, Y should not play Y1.

Where is this question from?

Yeah makes sense, thanks. From the D2 solomon papers, but they dont have the new spec questions with network flows/simplex linear programming, where could I get some more of those questions? Seen some in the old D1 papers but what about OCR D2 would you say they are related to edexcel spec? (only network flows/simplex)

You could always do the D2 Solomon paper and take the simplex and network flow question from the corresponding D1 paper. I imagine the OCR questions would be fine as well for network flows and simplex.

Why would player Y never play Y1??? says on mark scheme it shouldnt, im trying to do part B of question

Not through domination. So it must be obvious from well graph. Lines l2 and l3 will always be the best option for Y


Posted from TSR Mobile

Surely it is through domination? Y2 is always better than Y1 because the numbers are always smaller. From our perspective, Y's losses are shown, and Y2 is always less than Y1 so Y2 dominated Y1.

I suppose that can also be seen from the graph too.

-----------------------------

Anyway guys, I'm having trouble and I was wondering if you could help me.

Dynamic programming is fine when in graph form. But when it comes to these tables it is an absolute nightmare! Can anyone perhaps give me some strategies on how to identify what the stage, state, action and destination are?

Also there are some typical questions where some guy is travelling between countries, and the value is the profit subtract the travel costs or something.

However, which "end" do we add the profit on to?

Eg. Say I'm a singer on tour or something and I have to travel from A-B, then from B-C. Now say A-B and B-C both have travel costs of 10, but by visiting B I will make 100 from ticket prices.

My question is, when would I consider the ticket price in B? Would I say, A-B is -10 due to travel costs, +100 from the funds raised at B.

Or would I say, B-C is -10 due to travel costs, +100 raised from the funds at B. Do I consider the start vertex or end vertex?

Oh god I haven't explained myself well here, hopefully someone can still help, thanks.

Surely it is through domination? Y2 is always better than Y1 because the numbers are always smaller. From our perspective, Y's losses are shown, and Y2 is always less than Y1 so Y2 dominated Y1.

I suppose that can also be seen from the graph too.

-----------------------------

Anyway guys, I'm having trouble and I was wondering if you could help me.

Dynamic programming is fine when in graph form. But when it comes to these tables it is an absolute nightmare! Can anyone perhaps give me some strategies on how to identify what the stage, state, action and destination are?

Also there are some typical questions where some guy is travelling between countries, and the value is the profit subtract the travel costs or something.

However, which "end" do we add the profit on to?

Eg. Say I'm a singer on tour or something and I have to travel from A-B, then from B-C. Now say A-B and B-C both have travel costs of 10, but by visiting B I will make 100 from ticket prices.

My question is, when would I consider the ticket price in B? Would I say, A-B is -10 due to travel costs, +100 from the funds raised at B.

Or would I say, B-C is -10 due to travel costs, +100 raised from the funds at B. Do I consider the start vertex or end vertex?

Oh god I haven't explained myself well here, hopefully someone can still help, thanks.

I'm afraid i'm terrible lazy so just sorta skimmed through that (too many words )

I assume your asking about the dynamic programming questions where people travel between places and make money but then have to spend money on travelling and it all gets confusing

It doesn't matter which end (?) of the arc you consider, just choose one way and be consistent in your working, i personally add profits from the one you're leaving (in my head people get paid after doing work)

Since last year's dynamic programming was "make sth each month" and in 2011 was "traveling spent ". This this means they won't ask these two kinds of question this year?

Since last year's dynamic programming was "make sth each month" and in 2011 was "traveling spent ". This this means they won't ask these two kinds of question this year?