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The Edexcel D1 (18/05/12 - AM) Revision Thread

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I think most topics will come up, especially linear programming. I just dislike Scheduling.

Linear programming is easy enough with enough practice at defining constraints and realising which part to shade
Original post by Quantus Life
How do you decide which vertex to start from on an initial matching? Sometimes there are two free on the left side and it's not always obvious which one to start from


Either, there are multiple ways to solve matchings :smile:
Original post by Jorgeyy
I think most topics will come up, especially linear programming. I just dislike Scheduling.

Linear programming is easy enough with enough practice at defining constraints and realising which part to shade


I hope scheduling doesnt come up, if im being honest i dont really know what it is D:
Original post by bethany18
Me too but i'd say its a 90% chance really they always have a question on linear programming i think, i really hope this ones the exception and doesnt have it on ha


I really really hope so LOL
& if it does I just hope it's not worth a lot of marks
Original post by bethany18
I hope scheduling doesnt come up, if im being honest i dont really know what it is D:


I don't think many applicants will be 100% comfortable with it, and that will be reflected in the grade boundaries.
When doing the early and late time, for the early time you pick the latest time and when doing a backward pass for the late time you pick the shortest late time, right?
Reply 286
Original post by bethany18

Original post by bethany18
When doing the early and late time, for the early time you pick the latest time and when doing a backward pass for the late time you pick the shortest late time, right?


Exactly!
Original post by Jorgeyy
Either, there are multiple ways to solve matchings :smile:


But for example, Jan 2009 Question 4a, you could start from B or F but the mark scheme wants the path from B, how would I know which to choose in that example?
Reply 288
I'm really nervous about this exam. ):
Hopefully it'll be a nice paper. Good luck everyone! :smile:
Original post by Quantus Life
But for example, Jan 2009 Question 4a, you could start from B or F but the mark scheme wants the path from B, how would I know which to choose in that example?


Someone correct me if I'm wrong but I think that's because F can only go to 6, and in the initial matching E is already at 6
Original post by Quantus Life
But for example, Jan 2009 Question 4a, you could start from B or F but the mark scheme wants the path from B, how would I know which to choose in that example?


it doesnt matter which one you start from, it mentions on the mark scheme that it accepts b to 5 with the correct path etc
Original post by Quantus Life
But for example, Jan 2009 Question 4a, you could start from B or F but the mark scheme wants the path from B, how would I know which to choose in that example?


The mark scheme gives an example of one of the solutions.

There are multiple answers. You are probably right with your solution, ask a teacher to check?
Original post by whatever_x
Someone correct me if I'm wrong but I think that's because F can only go to 6, and in the initial matching E is already at 6


I think thats the answer theyre looking for but i dont think you'll lose marks for starting with b.
Reply 293
Original post by Quantus Life
But for example, Jan 2009 Question 4a, you could start from B or F but the mark scheme wants the path from B, how would I know which to choose in that example?

If you connected F to 6, and then E to 1, then D would be left unmatched, which means that it is not an improved matching, so you have to start at B to get an improved matching.
Yeah I'll do that. Maybe the mark scheme I have isn't the complete one. The only solution it gives is from B to 5 and none from F. Normally they have eg next to them when theres more solutions elsewhere in the mark scheme. Thanks
Original post by Jullith
If you connected F to 6, and then E to 1, then D would be left unmatched, which means that it is not an improved matching, so you have to start at B to get an improved matching.


Ah right, got it now thanks!
its just the definitions that i havent learnt. no point revising them all if they will hardly come up. i only know the definition of tree, spanning tree, bipartite graph, connected graph, :tongue:
Original post by James A
its just the definitions that i havent learnt. no point revising them all if they will hardly come up. i only know the definition of tree, spanning tree, bipartite graph, connected graph, :tongue:


I hope they give a definition and you give the name rather than me try and remember the definitions haha
Reply 298
how much does the layout of the table matter when you fill it in on a flowchart question???!
Original post by Quantus Life
Ah right, got it now thanks!


Apologies if I misdirected you,

The majority of questions allow many solutions and I should have checked the question myself before advising.

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