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Posers and Puzzles

Posers and Puzzles

  1. Donation 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 > 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. Standard member 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. Donation Acolyte
    Now With Added BA
    02 Feb '05 19:06
    Originally posted by DoctorScribbles
    Introduction to Algorithm Analysis
    More specific.
  4. Standard member royalchicken
    CHAOS GHOST!!!
    02 Feb '05 19:08
    Originally posted by Acolyte
    More specific.
    Optimisation and Control
  5. Standard member DoctorScribbles
    BWA Soldier
    02 Feb '05 19:39
    Originally posted by Acolyte
    More specific.
    Introduction to Analysis of Discrete Algorithms of Decision Theory
  6. Donation 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. Standard member 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. Standard member DoctorScribbles
    BWA Soldier
    02 Feb '05 21:31 / 1 edit
    Originally posted by Acolyte
    woah woah woah... I was looking for one key word!
    Introduction to Sorting Algorithms
  9. Donation 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:

    http://www.redhotpawn.com/board/showthread.php?threadid=2303
  10. Standard member 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:

    http://www.redhotpawn.com/board/showthread.php?threadid=2303
    Something with the word 'Code' in it, then.
  11. Donation 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 "Coding and Cryptography". 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
  12. Standard member 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

    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. Standard member genius
    Wayward Soul
    03 Feb '05 10:20
    Originally posted by royalchicken
    Mmmm, biscuits

    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...