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# D1 (Decision 1) 17 May 2013 Official Thread Watch

1. (Original post by Arsey)
that was a strange question, no it is 5 iterations, I didn't include the final location as an iteration stupidly.

Also on the CPA question I put my 5.5 line on day 6 so B can actually escape.
You on that lurk time? Hehehe.
2. (Original post by Arsey)
that was a strange question, no it is 5 iterations, I didn't include the final location as an iteration stupidly.

Also on the CPA question I put my 5.5 line on day 6 so B can actually escape.
Oh great, thank you for confirming that appreciated.
3. (Original post by posthumus)
Oh great, thank you for confirming that appreciated.
I guess we should round up now.
4. What time is Arsey going to post the paper?, is it 12 at night? or Saturday during the day sometime?
5. Okay guessing time. Here is what I expect to come up in the exam tomorrow.

Definitions - they love the reason for a dummy definition but I would expect definition on algorithms on networks or matchings.

Kruskal's, that is pretty certain to come up. Make sure you know the differences between Prim's and Kruskal's.

Sorting algorithm, you will either get Bubble or Quick, probably numerical descending order, which is likely to lead into...

Bin Packing - Make sure you know how to find the lower bound / proving a solution is maximal.

CPA - Maybe drawing an activity network and my money would be on a Gantt. Make sure you know how to find a lower bound from the activity network AND from a Gantt.

Linear Programming - Hammer linear programming, it is on every paper and is often the poorest answered. Unless you know how to go from context to a restriction you could be absolutely stuffed. Also make sure you know the basics, y = mx + c, if you don't know how to draw a line, do a table of values! you only need 3 points. I wouldn't be surprised if you get a decimal point but require an integer solution, so practise these.
6. (Original post by Vaner)
I guess we should round up now.
So let me get this right, do we always round up? Or do we round up if it's .5 & above??

When it says I can start and end at any point in a Chinese postman question, how do you workout those points? and if it gives you a start and tells you to end at any point then what do you do? what if it gives you an end and tell you to choose a start?

8. (Original post by posthumus)
Oh great, thank you for confirming that appreciated.
oh so we round up everytime the book is correct? even if we have 5.02 do we round to 6
9. (Original post by Arsey)
Okay guessing time. Here is what I expect to come up in the exam tomorrow.

Definitions - they love the reason for a dummy definition but I would expect definition on algorithms on networks or matchings.

Kruskal's, that is pretty certain to come up. Make sure you know the differences between Prim's and Kruskal's.

Sorting algorithm, you will either get Bubble or Quick, probably numerical descending order, which is likely to lead into...

Bin Packing - Make sure you know how to find the lower bound / proving a solution is maximal.

CPA - Maybe drawing an activity network and my money would be on a Gantt. Make sure you know how to find a lower bound from the activity network AND from a Gantt.

Linear Programming - Hammer linear programming, it is on every paper and is often the poorest answered. Unless you know how to go from context to a restriction you could be absolutely stuffed. Also make sure you know the basics, y = mx + c, if you don't know how to draw a line, do a table of values! you only need 3 points. I wouldn't be surprised if you get a decimal point but require an integer solution, so practise these.

A quck question sir, why is it sometimes that the lower bound does not tell you how many workers cause sometimes when you use the chart you get 4 and lower bound gets 3 why does it not work all the time
10. so..how do you find a lower bound from the activity network AND from a Gantt?
11. (Original post by Fortitude)
So let me get this right, do we always round up? Or do we round up if it's .5 & above??
Not quite sure, but in exam I'd round up. ( personally )
12. (Original post by dh1995)
so..how do you find a lower bound from the activity network AND from a Gantt?
From an activity network, it is the total weight of all activities divided by the weight of the critical path, to give you the lower bound of workers and from gantt chart, you do the same i guess
13. (Original post by Arsey)

CPA - Maybe drawing an activity network and my money would be on a Gantt. Make sure you know how to find a lower bound from the activity network AND from a Gantt.
How do you find the lower bound from a Gantt??
14. (Original post by Skilled)
From an activity network, it is the total weight of all activities divided by the weight of the critical path, to give you the lower bound of workers and from gantt chart, you do the same i guess
But sometimes the lower bound gives a wrong indication of how many workers there should be and so you have to use the cascade
15. (Original post by otrivine)
But sometimes the lower bound gives a wrong indication of how many workers there should be and so you have to use the cascade
so how do you do it with the cascade?
16. (Original post by otrivine)
But sometimes the lower bound gives a wrong indication of how many workers there should be and so you have to use the cascade

When it says I can start and end at any point in a Chinese postman question, how do you workout those points? and if it gives you a start and tells you to end at any point then what do you do? what if it gives you an end and tell you to choose a start?

17. (Original post by Vaner)
I guess we should round up now.
(Original post by otrivine)
oh so we round up everytime the book is correct? even if we have 5.02 do we round to 6
Yup always round up guys, sorry for the confusion hope you understand I think like they've done in the book using ">" sign would make it a bit easier to follow

(Original post by Fortitude)
So let me get this right, do we always round up? Or do we round up if it's .5 & above??
Oh we are talking about finding number of iterations for binary search used log to the base 2. It came up in Jan 2013

If you have 26 variables (like we did in Jan) then do logbase2(26) which gives you 4.7 , always round up so number of iterations is 5

The common method is to keep halving :

26/2 = 13
13/2 = [6.5] = 7
7/2 = [3.5] = 4
4/2 = 2
2/1 = 1

You had to half 5 times to get to 1 so maximum number of iterations is 5
18. I remember that question... Can you remember the last part of the last question??? Finding the lower bound from the gantt.. how do you do it?
19. (Original post by otrivine)
But sometimes the lower bound gives a wrong indication of how many workers there should be and so you have to use the cascade
Cascade and gantt charts are the same thing ??? Did you mean scheduling
20. (Original post by posthumus)
Cascade and gantt charts are the same thing ??? Did you mean scheduling
No you sometimes they want you to find the number of minimum workers needed , sometime they say use your gantt chart to do that but sometimes even if u want to use the lower bound it does not give u the same number of workers sometimes when u use the gantt you need 4 workers and in lower bound you get 3 why the difference

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