[Search for users]
[Overall Top Noters]
[List of all Conferences]
[Download this site]
Title: | Mathematics at DEC |
|
Moderator: | RUSURE::EDP |
|
Created: | Mon Feb 03 1986 |
Last Modified: | Fri Jun 06 1997 |
Last Successful Update: | Fri Jun 06 1997 |
Number of topics: | 2083 |
Total number of notes: | 14613 |
522.0. "missing number can be anything!" by RDGE28::FLASH (project account) Wed Jun 25 1986 11:29
(Simon Clinch)
You will probably be familiar with IQ-test problems of the kind,
"Find the next number in the sequence..." Can you disprove the
validity of such problems by the following means:
Let T1,T2,...,Tn-1 be the terms of the sequence you are given
and Tn be the "next number in the sequence".
Find a generating function y=g(x,T1,...,Tn) that for any given
values of T1,...,Tn-1 will generate the equation y=f(x,Tn) that
satisfies the following conditions:
a) f(i) = Ti for 1 <= i <= n-1, and
b) f(n) = Tn for all Tn in R.
Thus proving for example that if you are asked to find the next
number in the sequence:
1,2,3,4,5,6
that the answer is -1.1, because your generating function
y=g(x,1,2,3,4,5,6,-1.1,0,0,...) will result in the particular
equation y=f(x) where f(1)=1, f(2)=2, ..., f(6)=6 and f(7) = -1.1 (!)
T.R | Title | User | Personal Name | Date | Lines |
---|
522.1 | | AURORA::HALLYB | Free the quarks! | Wed Jun 25 1986 13:20 | 12 |
| The standard answer to this kind of argument runs along the lines
that, sure, you can produce generating functions all over the place
but the "right answer" is the one the smart people come up with.
If you are given the sequence: 1,2,3,4,5,6,__ it is natural to
assume that most people will answer 7. Anybody answering "-1.1"
is clearly just being precocious, and deserves to get docked.
Another argument holds that Occam's Razor applies, i.e., among all
the right answers, the simplest is best.
John
|
522.2 | | CLT::GILBERT | Juggler of Noterdom | Wed Jun 25 1986 17:21 | 4 |
| This type of number sequence problem was discussed at length in
a "Mathematical Games" (or "Metamagical Themas"?) column of
"Scientific American" earlier this year. Can someone provide
a tighter bound?
|
522.3 | 1,2,3,5,7,...? | TAV02::NITSAN | Nitsan Duvdevani, Digital Israel | Thu Jun 26 1986 04:53 | 4 |
| This CAN be defined mathematically (sometimes!) as finding the next
number, using such a "g" function with the minimal complexity...
ND
|
522.4 | ...or you could have a go at the problem! | RDGE28::FLASH | project account | Thu Jun 26 1986 08:53 | 31 |
| re .1 -- Yes, if there is a simple answer or you can find a definition
of simple that applies to all possible problems. In my opinion the
notion of simple is relative and therefore such an argument is
inapplicable to testing intelligence which is also relative. For
example the test compiler's idea of simple may be different to that
of the lesser able candidate, but more importantly, it may be
different to that of the candidate of very high intelligence. As
a result the intelligent persons idea of a simple answer will include
a larger range of valid answers.
Occam's razor was originally applied to Natural law hypotheses, many
of which were discovered to be too simple. Indeed, we have the
more advanced razor of Einstein which, translated into English,
would be, "The Creator is subtle but not mischievous."
The other point is that the notion of obvious, apart from being
relative, is context driven. In fact I deliberately placed this
problem after the previous one to enable the reader to benefit
from a contextual path to an answer that, although this path is
subtle, is definitely there. What is obvious will generally
depend upon what previous questions have just been answered.
As de Bono pointed out, the state of the brain is not analagous
to a towel on which ink spots may be dropped in any sequence but
in the same quantities at the same points to produce the same
pattern, but is more analagous to a jelly on which you drop hot
ink, so that the flow of ink will create channels dependent on
the order in which you made the previous drops. (Ref. "PO: Beyond
Yes and No", Edward de Bono)
But my aim was in fact to present a mathematical problem for which
I do have an answer, rather than provoke philosophical discussion
alone!
|
522.5 | Spoiler (SDC) | RDGE28::FLASH | project account | Thu Jun 26 1986 13:30 | 15 |
| Spoiler follows:
n i-1 n
--- --- ---
\ | | | |
/ T ( | | (x-j) | | (x-j)
--- i
i=1 j=1 j=i+1
y = ------------------------
n i-1 n
--- --- ---
\ | | | |
/ ( | | (x-j) | | (x-j)
---
i=1 j=1 j=i+1
|