# Everyone's favourite problem

Acolyte
Posers and Puzzles 02 Feb '05 14:56
1. Acolyte
Now With Added BA
02 Feb '05 14:56
The following is a question from one of my example sheets, ie questions for the purpose of practising material covered in lectures:

You are given m apparently indentical coins, one of which may be a forgery. Forged coins are either too light or too heavy. You are also given a balance, on which you may place any of the coins you like. The coins placed in either pan may be together heavier or lighter than those in the other pan, or the pans may balance.
You are allowed at most 3 uses of the balance. Show that if m &gt; 13 then you cannot be sure of detecting the forgery and its nature.

Sound familiar? Well, I'm not asking you to do my homework: your challenge is not to solve the problem above (which has already appeared in P+P more than any other problem, I suspect). Your challenge is to answer the following: what is the name of the lecture course for which the problem has been set? The metaphorical biscuit will go to the first guess that is sufficiently close to the answer. As a hint: you might find it helpful to look at one of my earlier posts on the RHP forums, in which I give a fairly thorough analysis of the balance problem, long before I started attending this particular lecture course.
2. DoctorScribbles
BWA Soldier
02 Feb '05 15:35
Originally posted by Acolyte
The following is a question from one of my example sheets, ie questions for the purpose of practising material covered in lectures:

You are given m apparently indentical coins, one of which may be a forgery. Forged coins are either too light or too heavy. You are also given a balance, on which you may place any of the coins you like. The coins place ...[text shortened]... analysis of the balance problem, long before I started attending this particular lecture course.
Introduction to Algorithm Analysis
3. Acolyte
Now With Added BA
02 Feb '05 19:06
Originally posted by DoctorScribbles
Introduction to Algorithm Analysis
More specific.
4. royalchicken
CHAOS GHOST!!!
02 Feb '05 19:08
Originally posted by Acolyte
More specific.
Optimisation and Control
5. DoctorScribbles
BWA Soldier
02 Feb '05 19:39
Originally posted by Acolyte
More specific.
Introduction to Analysis of Discrete Algorithms of Decision Theory
6. Acolyte
Now With Added BA
02 Feb '05 20:55
Originally posted by DoctorScribbles
Introduction to Analysis of Discrete Algorithms of Decision Theory
woah woah woah... I was looking for one key word! RC's suggestion is sensible (have you been reading 'Courses in the Mathematical Tripos', Mark?) but incorrect.
7. royalchicken
CHAOS GHOST!!!
02 Feb '05 21:24
Originally posted by Acolyte
woah woah woah... I was looking for one key word! RC's suggestion is sensible (have you been reading 'Courses in the Mathematical Tripos', Mark?) but incorrect.
I have as much Google skill as the next flu-ridden, smelly, unshaven mathmo.
8. DoctorScribbles
BWA Soldier
02 Feb '05 21:311 edit
Originally posted by Acolyte
woah woah woah... I was looking for one key word!
Introduction to Sorting Algorithms
9. Acolyte
Now With Added BA
02 Feb '05 23:58
Originally posted by DoctorScribbles
Introduction to Sorting Algorithms
Nope. It seems my hint wasn't very helpful, as the forum searcher isn't as effective as it could be. Here is the relevant thread:

10. royalchicken
CHAOS GHOST!!!
03 Feb '05 00:03
Originally posted by Acolyte
Nope. It seems my hint wasn't very helpful, as the forum searcher isn't as effective as it could be. Here is the relevant thread:

Something with the word 'Code' in it, then.
11. Acolyte
Now With Added BA
03 Feb '05 00:40
Originally posted by royalchicken
Something with the word 'Code' in it, then.
That's biscuit-worthy: the course is called &quot;Coding and Cryptography&quot;. The strange thing is, I gave that solution involving 'weighing codes' more than two years ago, when I wasn't even a student, and yet I'm pretty sure that my lecturer wants me to use my 3rd year Tripos maths knowledge to answer the question in exactly the same way. Maybe they don't teach us that much after all ðŸ˜‰
12. royalchicken
CHAOS GHOST!!!
03 Feb '05 01:02
Originally posted by Acolyte
I'm pretty sure that my lecturer wants me to use my 3rd year Tripos maths knowledge to answer the question in exactly the same way.
Mmmm, biscuits ðŸ™‚

Come to think of it, I once confused your avatar with a coin, so you can impress your lecturer by working it out in terms of biscuits instead, or cookies if your lecturer is EDG.
13. genius
Wayward Soul
03 Feb '05 10:20
Originally posted by royalchicken
Mmmm, biscuits ðŸ™‚

Come to think of it, I once confused your avatar with a coin, so you can impress your lecturer by working it out in terms of biscuits instead, or cookies if your lecturer is EDG.
i think it used to be a coin, or someone elses was/is a coin.

i thought it was a coin too...ðŸ˜›