HDTenEightyP/NetNews huggingface dataset:
From: arromdee@jyusenkyou.cs.jhu.edu (Ken Arromdee)
Subject: Re: Spacewarp wonders 
Organization: Johns Hopkins University CS Dept.
Date: Thu, 23 Jul 1992 21:02:38 GMT

In article <1992Jul23.133333.4885@hellgate.utah.edu> tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:
>  Your spaceship has been sucked through a spacewarp, and then crashed
>onto a place.  The place is foggy, so one can not see more than a few
>kilometers clearly.  There is always a fairly bright light here.
>Also, you have access to whatever science gear you might like, as it
>was aboard your craft.  There are lots of life forms, all of them huge.
>1) How would you be able to tell if the planet was a sphere, or a nearly flat
>   plane extending in all directions?

Get a gyroscope, and start travelling.  If your gyroscope appears to
"change direction", you're on a sphere.

>2) How would you be able to tell if you had travelled forwards or backwards
>   through time 5 billion years or more?

Check the 3 degree K background radiation.

>3) How would you be able to tell if you and your space ship were somehow
>   shrunken in passage?

This question cannot be answered; it's not clear what it means for something
to be shrunken.  For instance, if a shrunken object is one which is smaller
in size, but retains the same mass, there are certain obvious answers.  If
it's smaller in size but retains the same X, the answer differs depending on
the value of X.

For instance, one might try to measure the time it takes for light to get
from one end of something of known length to the other.  However, this
assumes that "shrunken light" moves as fast as unshrunken light.  If it
doesn't, the experiment is different: compare the speed of outside light
to that of spaceship light.
--
Hi! Ani mutacia shel virus .signature. Ha`atek oti letoch .signature shelcha!

Ken Arromdee (UUCP: ....!jhunix!arromdee; BITNET: arromdee@jhuvm;
     INTERNET: arromdee@jyusenkyou.cs.jhu.edu)
Newsgroups: rec.puzzles
From: tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman)
Subject: Frog and Turtle play 20
Date: 29 Jul 92 11:59:10 MDT
Organization: University of Utah, CompSci Dept

Frog:(eager for retribution) Lets play twenty questions!

Turtle: Okay, pick anything you like.

Frog:  Anything?  Alright, lets go.  It will be impossible for you to get it
       now in 20 questions.

Turtle: Uh Oh.  That is not possible to do, is it?

Frog: Yes, 19 left.

Turtle: It is not my 21st question is it that I have to guess?

Frog: No.  18 left.

What was it that Frog picked?  

Newsgroups: rec.puzzles
From: yoo@well.sf.ca.us (Young-Kyu Yoo)
Subject: Re: Proof of -1 = 1
Organization: Whole Earth 'Lectronic Link
Date: Wed, 29 Jul 1992 19:24:30 GMT


>                               sin x
>                                _____  = 6
>                                  n
>
>Prove it.

Spoiler follows...


The n's cancel leaving you with   si x = 6.
Newsgroups: rec.puzzles
From: russotto@eng.umd.edu (Matthew T. Russotto)
Subject: Re: Different objects
Date: Sun, 26 Jul 92 19:57:45 GMT
Organization: College of Engineering, University of Maryland, College Park

In article <24JUL199219321012@zeus.tamu.edu> dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:
>>>>wjcastre@magnus.acs.ohio-state.edu (W.Jose Castrellon G.) writes:
>>>>>>How about constructing two different objects that cannot be distinguished
>>>>>>by reasoning within well-established theories (plus lab data -- references to
>
>>In article <1992Jul19.192213.10027@eng.umd.edu>, russotto@eng.umd.edu (Matthew T. Russotto) writes...
>>>Hmm...  I suppose it would.   Neutrons and anti-neutrons should work,
>>>but I can't think of a way of holding them, and besides, they are
>>>unstable.  
>
>Okay, how about optical trapping of atoms? Hydrogen and anti hydrogen for
>example. Or probably any different atoms would be hard to tell apart. Any
>experts out there?

I don't think neutral atoms will do it-- remember that we are assuming
infinitely sensitive instruments, and it ought to be possible to
determine if the massive particle is positive or negative.  There
would probably be the same problem with neutrons-- you'd have to stick
with neutrinos, but I don't know how to enclose them...

-- 
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
Some news readers expect "Disclaimer:" here.
Just say NO to police searches and seizures.  Make them use force.
(not responsible for bodily harm resulting from following above advice)
Newsgroups: rec.puzzles
From: pauln@cbnewsi.cb.att.com (paul.h.nelson)
Subject: Re: carrying the torch (HINT)
Organization: AT&T
Date: Mon, 27 Jul 1992 17:19:32 GMT

1.  Turn on #1 and #2.

2.  Wait 5 minutes or so.

3.  Just before going into the room, turn off #1.


#1 bulb will be off and hot
#2 will be on by itself.
#3 will be off and cold.


Paul Nelson
Bell Labs
Naperville, IL
Newsgroups: rec.puzzles
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: carrying the torch
News-Software: VAX/VMS VNEWS 1.41    
Keywords:  *** SPOILERS ***
Organization: Texas A&M University, Academic Computing Services
Distribution: rec
Date: Sat, 25 Jul 1992 05:04:00 GMT

ph@venturi.ama.caltech.edu (Paul Hardy) writes...
>You are in a room with three switches.  Each switch controls a light bulb
>in another room; that room is not visible to you.  You know which position
>is on and which is off for the three switches, and may throw them in any
>order you like, then go into the other room, where you must determine which
>switch was connected to which light.  How can this be done?

>3 6 9 27 ?

*** SPOILER ALERT ***




















Set them to 'on' 'off' and 'hot'.

3^3^3, whatever that means.

Dave Ring
dwr2560@zeus.tamu.edu
From: jsb@panix.com (J. S. B'ach)
Newsgroups: rec.puzzles
Subject: Re: The Frog Puzzle
Date: 30 Jul 92 22:10:09 GMT
Organization: Panix, NYC

In article <1992Jul30.153923.2088@gmuvax2.gmu.edu> kaufman@gmuvax2.gmu.edu (Ken Kaufman) writes:
)In article <1992Jul30.054932.14400@athena.mit.edu> jimhsu@athena.mit.edu (Jimmy M.D. Hsu) writes:
)
)
)> What if Frog is referring to a 21-digit number generated by the answers
)> to each of the twenty questions?  Have the nth digit of the number
)> correspond to the answer of the nth question like so:
)
)Big problem here.  Presumably, the 21st digit (and any beyond) must be
)determined by something as well - whether by Frog's preselection,
)Turtle's questioning, or some other factor, it can presumably be
)guessed.  The 20th question: "Is it the number generated by my questions
)followed by a 1?" *could* be right.

If it could be stated, it could be guessed (if it is determinate before the
questions are asked).
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Newsgroups: rec.puzzles
Subject: Re: 3 puzzles
Date: 23 Jul 1992 23:43:00 GMT
Distribution: rec.puzzles
Organization: Texas A&M University, Academic Computing Services
News-Software: VAX/VMS VNEWS 1.41

markc@eomer.sw.stratus.com (Mark Christensen) writes...
>	What is the first number, when spelled out (e.g. O-N-E) is
>in alphabetical order?

Eight or forty, depending on which grammatical mistake was made.

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: rec.puzzles
From: tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman)
Subject: Frog's tea party
Date: 24 Jul 92 16:47:42 MDT
Organization: University of Utah, CompSci Dept

The Frog was having his friend Turtle over for tea.  He got out his tea,
sugar, and cookies on his silver platter with silver spoons, and his
nicest pot and cups. At 1:00 Frog poured one cup, then decided to wait, 
although his friend was seldom late.  At 1:30 he poured the next, and Turtle
came in....

Turtle: Sorry I am late, got bogged down...

Frog:   That's okay, but since you are late, one of these cups are cold, and
   the other hot.  Neither have visible steam, and you may not touch directly
   or indirectly either one, you pick which you like....

Turtle: Hmmmmm.... (how did the Turtle figure out which cup was hot?)

Frog: I have 5 cookies.  These two are for you, and these two for me.  Whoever
      finishes off their cookies last gets the extra one.  Please be fair.

Turtle ended up getting the extra cookie- without too much delay.  How?

Newsgroups: rec.puzzles
From: mmdh@cbnewsf.cb.att.com (Mazen Mokhtar)
Subject: Re: Ten equals 9.9999....
Organization: AT&T
Date: Tue, 28 Jul 1992 13:49:24 GMT

In article <1992Jul27.150032.12515@phillip.edu.au> t9114145@phillip.edu.au writes:
>Alright, if 9.999... = 10, then why isn't .33333... exactly 1/3?

  Who said it is not? 0.333... is exactly 1/3.

>I don't see how they are equal. I know that 9.999... with infinite 9's is
>very close to 10, but that .0000...0001 is what you need to make exactly 10.

  There is no number such as 0.00...0001, is this a terminating decimal? You
are refering to is zero.

                       1
  0.00...001 is lim  -----, which is easily found to be zero.
                x->oo   x
                      10

  Two real numbers are equal or one is greater than the other.
  Consider:                         0.00...001,
            is it less than         0.00...002 ?
            How about               0.00...010 ?
            but this is the same as 0.00...001 .

  Now, 10 * 0.00...001 = 0.00...010 = 0.00...001, but solve:
       10 * x = x ==> x = 0  This is the unique solution.

  Therefore, 0.00...001 = 0.

Regards,

Mazen Mokhtar
From: steppe@ccwf.cc.utexas.edu (Top Changwatchai)
Newsgroups: rec.puzzles
Subject: mini-mysteries
Date: 31 Jul 92 07:38:00 GMT

Can someone please send me a list of FAQ's for rec.puzzles, or let me know
where I can find such a list?  Specifically, I'm looking for a list of those
mini-mysteries, where the storyteller gives a short mysterious story, and
the audience tries to figure it out, via yes-no questions.  For example,
there's one where a woman reads in the newspaper about a man whose wife has
just died.  Immediately, the woman exclaims, "He killed her!"  The woman
had never met the man or his wife.  The audience is supposed to discover how
the woman knew that the man had killed his wife.

Thanks,

Top
 


Newsgroups: rec.puzzles
From: otten@icase.edu (John Otten)
Subject: Re: Crossing a river
Organization: ICASE/NASA Langley
Date: Fri, 31 Jul 1992 12:47:17 GMT

In article <1992Jul30.234624.21370@fid.morgan.com>, sethb@fid.morgan.com (Seth Breidbart) writes:
>In article <1992Jul30.173556.5883@iscsvax.uni.edu>
>althof5805@iscsvax.uni.edu writes:
>>Three kings are travelling with three thieves.  The kings know that if, at any
>>time, thieves outnumber kings (e.g. if one king leaves to take a leak behind an
>>accacia tree), the thieves will kill this outnumbered kings.  The kings may
>>outnumber the thieves, and the number may be equal for both sides (one king and
>>one thief may go to take a leak together), but the thieves must *never*
>>outnumber the kings.
>>
>>They come to a larger river which curves to the south.  The kings realize that
>>they must cross this river (going around the bend) to reach the path they seek. 
>>The only problem is this:  there is a boat available which only carries two
>>people.  Thus, they will have to play "ferry" to get all of them across.
>>
>>How can the kings arrange things so that there are never more thieves than
>>kings on either side of the river?  Swimming is out (unless they decide to pick
>>up a few pet alligators), and each time the boat returns to the starting point
>>there will be an uneven number of people on each side of the river.
>>
>>Whatcha gonna do?
>
>0. KKKTTT
>1. Two thieves row across.  KKKT   TT
>2. One thief rows back.  KKKTT     T
>3. Two thieves row across.  KKK    TTT 

4. The three thieves leave the boat on their side of the river and run away.
   (well, that is what *I* would do if I was one of the thieves :-)

>4. One thief rows back.     KKKT   TT
>5. Two kings row across     KT     KKTT
>6. One king & one thief row back.   KKTT    KT
>7. Two kings row across.      TT    KKKT
>8. Thief rows back.        TTT    KKK
>9. Two thieves row across.   T    KKKTT
>10. One thief rows back.     TT   KKKT
>11. Two thieves row across.        KKKTTT
>
>Alternatively, steps 1 and 2 can be king and thief row across, king
>rows back.
>
>Seth		sethb@fid.morgan.com
>
John
otten@icase.edu
Newsgroups: rec.puzzles
From: killer@niksula.hut.fi (Kalle Kivimaa)
Subject: Re: Ten equals 9.9999....
Organization: Helsinki University of Technology, Finland
	<1992Jul29.000030.4839@fid.morgan.com>
	<1992Jul28.232532.3577@hellgate.utah.edu>
Date: Wed, 29 Jul 1992 16:46:32 GMT

In article <1992Jul28.232532.3577@hellgate.utah.edu> tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:

   >If two numbers are different, then there's another number between
   >them.  (Actually, a lot of such numbers.)

     41.999999.... and 42

Now, to all those r.p readers who agree with Kenneth I quote:

"[Theorem:] Between any two real numbers there is a rational number and an
irrational number."

Unfortunately, it is not proven in the text, but if you want to
disagree, please contact the author Stanley I. Grossman, Univ. of
Montana and tell him that he is wrong.  If you can convince HIM then
come back and post.

--
************************************************************************
* The night sky over the planet Krikkit is the least interesting sight *
* in the entire Universe.  -- Douglas Adams, HHGTG                     *
************************************************************************
From: filfeit@rael.Tymnet.COM (Fil Feit)
Newsgroups: rec.puzzles
Subject: Re: preposition proposition
Date: 30 Jul 92 12:44:05 GMT
Reply-To: filfeit@rael.Tymnet.COM
Organization: Sun Microsystems

In article 14286@husc3.harvard.edu, wald2@husc9.harvard.edu (Kevin Wald) writes:
>
>Actually, in English it is possible to get sentences ending in abitrary
>numbers of prepositions which actually function as prepositions(of course,
>if they have to be *different* prepositions, eventually you run out of
>vocabulary). All you have to do is take the rule that a noun phrase
>can be of the form "the OBJECT_OF_PREPOSITION SUBJECT VERB DIRECT_OBJECT
>PREPOSITION," and note that since the DIRECT_OBJECT is itself a noun 
>phrase, we can expand recursively, adding one preposition with each 
>iteration. Thus, starting with the simple sentence "Which bed is the
>mouse under?" we can get
>
> [clear examples deleted]

Excellent description of the general solution!  And an inadvertant
explanation of why it's so #$%^ difficult to make machines parse
(nothing close to understand) a language as bizarre as English.

Remember those sentence generators that floated around on PDP-x machines
many years ago?  They'd follow rules, much like Mr. Wald's example, but take
recursivity (?sp ?word??) to an absurd limit.  A rule for "subject" like
ADJECTIVE SUBJECT could turn out a sentence like:

The blue blue orange small bright thoughtful man is yellow.

which brings me back to my .sig
--f2
--------------------------
  Time flies like an arrow.
  Fruit flies like a banana.
From: Virginia.A.Reed@dartmouth.edu (Virginia A. Reed)
Newsgroups: rec.puzzles
Subject: Re: Ten equals 9.9999....
Date: 31 Jul 92 16:31:46 GMT
Organization: Dartmouth College, Hanover, NH

If 9.9999... + 0.00...01=10, and 0.00...01 is infinitely small(which it
is), then it can be assumed as zero.
therefore:

9.9999...- 0.000..01 = 9.999...

It was stated before that
                             x=9.999...
                           10x=99.999...
                           9x=90
                             x=10=9.999...

If 9.999...=10, then
9.9999...-0.000...01=10
add 0.000...01 to both sides:
9.9999...=10.000...01
-0.000...01=0.000...01

taken to its extreme, you could prove that 7=-7, or that 2341=-2341
Newsgroups: rec.puzzles
From: de@cray.com (Duane Eitzen)
Subject: Re: Frog and Turtle play 20
Organization: Cray Research, Inc.
Date: 29 Jul 92 18:20:27 CDT

In article <1992Jul29.115911.9375@hellgate.utah.edu> tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:
>Frog:(eager for retribution) Lets play twenty questions!
>
>Turtle: Okay, pick anything you like.
>
>Frog:  Anything?  Alright, lets go.  It will be impossible for you to get it
>       now in 20 questions.
>
>Turtle: Uh Oh.  That is not possible to do, is it?
>
>Frog: Yes, 19 left.
>
>Turtle: It is not my 21st question is it that I have to guess?
>
>Frog: No.  18 left.
>
>What was it that Frog picked?  
>
If Frog was telling the truth when he said it was gauranteed to take more
than twenty questions, then clearly I have insufficient information to
answer your question (i.e. naming the "thing" after two questions would 
invalidate the assertion that Frog was telling the truth).

If Frog was lying when he said this, then clearly the answer is "avacado
fridge magnet".

Duane.
Newsgroups: rec.puzzles
From: rabino@eng.umd.edu (Michael Rabinovitz)
Subject: Re: Proof of -1 = 1
Date: Fri, 24 Jul 92 15:56:39 GMT
Organization: University of Maryland, College Park, College of Engineering

In article <chan.711960216@s1.elec.uq.oz.au> chan@elec.uq.oz.au (Chuen Wen Chan) writes:
>
>>	sqrt(-1) = sqrt(-1)
>
>>	sqrt( -1 / 1 ) = sqrt( 1 / -1 )
>
>>	sqrt(-1)    sqrt(1)
>>	-------- = ---------
>>	sqrt(1)     sqrt(-1)
>
>>	now cross multiply and we get:
>
>>	-1 = 1  QED
>
>Regarding the above problem, I DO know that the third line is 
>wrong (ie: i != 1/i).  The point is the derivation up to that
>point looks legal.
>
	IMHO, the reason line 3 is wrong is the expansion of line 2
assumes 
		sqrt(a/b) = sqrt(a) / sqrt(b) 
rather than
		sqrt(a/b) = sqrt(a) * sqrt(1/b).

	Using this form to evaluate line 2 makes the "paradox" go away.

					Mike Rabinovitz
					rabino@eng.umd.edu

Anybody wanna see a calculus based "proof" that 1=2 ?

-- 
         	                        Mike Rabinovitz 
					rabino@eng.umd.edu
Newsgroups: rec.puzzles
From: radcliff@csd4.csd.uwm.edu (David G Radcliffe)
Subject: Re: Ten equals 9.9999....
Organization: University of Wisconsin - Milwaukee
Date: Wed, 29 Jul 1992 06:19:54 GMT

tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:
: >If two numbers are different, then there's another number between
: >them.  (Actually, a lot of such numbers.)
: 
: >If you can't give an example of a number between 9.99999... and 10,
: >please don't post anymore to this thread.
: 
: 
: SAY WHAT?  This is the silliest bit of nonsense ever.  "If two numbers are
: different, then there's another number between them".  Let's consider the
: integers, and I will give you 2 and 3.  Now, if they are different, there
: must be an integer between them.  Well, what is it?

While were at it, why don't we consider the quaternions?

: 
: Now, if you assert that the above is true for REAL's then you better have
: some reason, for I can just as easily assert the opposite.  As a matter of
: fact, I can show you two numbers which are different, which do not have any
: number between them...
:   41.999999.... and 42

Theorem.  If a < b and c = (a + b)/2 then a < c < b.

Proof:
	      a    <      b
            a + a  <    a + b
       (a + a) / 2 < (a + b) / 2
              a    <      c

              a    <      b             
            a + b  <    b + b 
       (a + b) / 2 < (b + b) / 2 
	      c    <      b

Therefore, a < c < b.

--
David Radcliffe                                
radcliff@csd4.csd.uwm.edu            
Newsgroups: rec.puzzles
From: tjoa@cory.Berkeley.EDU (Richard Tjoa)
Subject: Re: carrying the torch
Summary: The lightbub problem, and a sequence problem thrown in for fun!
Keywords: sequence light bulb switches on off numbers sex
Organization: You see--Burke Lee
Distribution: usa
Date: Sat, 25 Jul 1992 08:09:34 GMT

In article <PH.92Jul24183436@venturi.ama.caltech.edu> ph@venturi.ama.caltech.edu (Paul Hardy) writes:
>You are in a room with three switches.  Each switch controls a light bulb
>in another room; that room is not visible to you.  You know which position
>is on and which is off for the three switches, and may throw them in any
>order you like, then go into the other room, where you must determine which
>switch was connected to which light.  How can this be done?

Remove the panel covering the switches and wire different ohmage resistors in
series with the switches.  Turn them all on, run into the other room and
check the brightness.  If they are not noticibly different, remove the bulbs,
whip out your ammeter and check the amperage.


-Richard
Non-"The Cuckoo's Egg" readers:  What's the next number in the series...
1 11 21 1211 ...
(And why?)
Newsgroups: rec.puzzles
From: tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman)
Subject: Alien colonization
Date: 22 Jul 92 15:34:16 MDT
Organization: University of Utah, CompSci Dept


  The alien Ddiv lives in a universe which is three dimensional, and has
the planets evenly spaced throughout as in a 3D grid.
Ddiv is planning to have children- each child will require one full planet
to live on.  Ddiv is also immortal, and wishes to keep living forever.
He wishes to be fair to his children- so he will only have as many 
children as each of his children can have.  He would not have any children
if any single one of his offspring could not have any children, so
his grandkids, great grandkids, and so on must be able to have as many
children as he has. 


  How many children can Ddiv have? (Ddiv has children by dividing)
Newsgroups: rec.puzzles
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: HAD x 11 (spoiler?)
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Tue, 21 Jul 1992 21:31:00 GMT

filfeit@rael.Tymnet.COM writes...
>Had had had "had".  Had Had had "had, had", Had had more of a chance to win.
>or something like that.
>--f2

jaw@cs.arizona.edu writes...
>   Jack, while Jill had had "had," had had "had had."  "Had had" had had 
>   a better effect on the teacher.

Hmmm...

Jim, while Fil had had "Had had had 'had'.  Had Had had 'had, had', Had
had... ," had had "had had 'had,' had had 'had had.'  'Had had' had had... ."
"Had had 'had,' had had 'had had.'  'Had had' had had..." was the more natural
of the two. :-)

Dave Ring
dwr2560@zeus.tamu.edu
From: markc@eomer.hw.stratus.com (Mark Christensen)
Newsgroups: rec.puzzles
Subject: Re: 3 puzzles
Date: 23 Jul 92 17:15:23 GMT
Article-I.D.: transfer.5083
Reply-To: markc@eomer.sw.stratus.com (Mark Christensen)
Distribution: rec.puzzles
Organization: Stratus Computer, Hardware Engineering

In article <1992Jul23.142526.9834@cs.cornell.edu> karr@cs.cornell.edu (David Karr) writes:
><SPOILERS ahead>
>
>In article <5071@transfer.stratus.com> markc@eomer.sw.stratus.com (Mark Christensen) writes:
>
>
>>[1]
>>	What is the first number, when spelled out (e.g. O-N-E) is
>>in alphabetical order?
>
>eight

Ummm!  Not quite.  The letter "h" comes before "i".  Try
again.


>
>>[2]
>>	A man walks into a hardware store and goes to the clerk
>>and says he wants an item.  "I'll take one", he says. The clerk
>>says that that will be $1.  "How much for 12", the man asks?
>>That will be $2 the clerk respond.  "OK, I'll take 125", the
>>man says, to which the clerk responds, "That will be $3 please".
>>What is the item that the man is buying.
>
>Stick-on numbers (e.g. for his mailbox).  $1 per digit.
>125 -> 3 digits -> $3.

Exactamundo!


>
>>[3]
>>The first prisoner took his blindfold off, looked at the other
>>two prisoner's hats and said, "I can't tell what color my hat is".
>
>(N,COLOR) = "The Nth prisoner is wearing a COLOR hat"
>There are only two white hats, so if (2,white) and (3,white) then
>1 knows that (1,red).  So (2,red) or (3,red).
>
>>The second prisoner also responded as the first prisoner.
>
>If (3,white) then (2,red) and prisoner 2 would know (2,red).
>So the third prisoner's hat is red, and he or she doesn't even
>need to look.

Correct.  It is red.

>
>-- David Karr (karr@cs.cornell.edu)
Newsgroups: rec.puzzles