HDTenEightyP/NetNews huggingface dataset:
From: bcash@crchh410.BNR.CA (Brian Cash)
Subject: Re: 1/2, 1/3, boy girl the answer to life & everything
Date: Wed, 27 Jan 1993 19:14:38 GMT
Reply-To: bcash@crchh410.BNR.CA (Brian Cash)
Organization: Bell-Northern Research Ltd.

>From: cooper@cbnewsg.cb.att.com (Ralph 'Hairy' Moonen)

Everything stated is corect, until this:
>   A coin is tossed twice. You are told that *at least* one of the tosses
>   produced heads. What is the probabilty that THE SECOND (and *not* the
>   first!) toss produced heads to make both tosses heads. In this case,
>   the permutations of HT and TH are distinhuished and different. the
>   answer now is 1/3. People read the original question and see the above
>   one, because it's easy to make this mistake. 

What is the prob. that the 2nd toss is heads and not the first, making
both tosses
heads?  Zero!  If the first toss is not heads, then they can't be both heads!
I think you want to re-state this.
I think this is what you mean:

A coin is tossed twice. You know that *at least* one of the tosses is heads.
What is the prob. that the second toss is heads?  Ans = 2/3.
What is the prob. that they are both heads? Ans = 1/3.



The main point with the sibling/coin problem is whether or not the the
probabilities are independent or not.  If you say "One is x, what is the
prob. that the other is also x?", then the probabilities are independent and
the fact that "One is x" doesn't change anything.  If you say "At least
one is x 
(out of two), what is the prob. that number 2 is x?" links the prob.s because
if the first is not-x, then the second _must_ be x, so the answer is different.

Does this sound reasonable?   (I got nailed for missing this on the
first pass :)

Brian /-|-\
Newsgroups: rec.puzzles
From: adams@mundoe.maths.mu.OZ.AU (Tim Adam (c/o Jacinta))
Subject: Re: Dividing apples (SPOILER)
Organization: Department of Mathematics, University of Melbourne
Date: Tue, 26 Jan 1993 12:48:04 GMT

>From: padmanab@ecs.umass.edu
>Here is a SIMPLE problem I came across long ago. 
>I am posting it because I think it has a wonderful 
>solution. 
>
>Suppose there are 25 identical apples. How many 
>ways can you divide them among three people? Also, 
>all the apples must be divided among them. 

In article <C1E5Du.D3B@news.rich.bnr.ca> bcash@crchh410.BNR.CA (Brian Cash) writes:
>Is it 351?  I figured it this way:
> (etc...)
>I'm rather math-impaired, so I would like to know 1) is this right? 2)
>what is a more "scientific" way of finding the answer.

The really nice way that I think the poser refers to is to think
of picking two distinct numbers from 0 to 26 inclusive.
Call the smaller x and the larger y.
Then the first person gets x apples, the second y-x-1 apples,
and the third 26-y.  Note the most anyone can get is 25, the least 0,
and the total is also 25.
The number of ways of doing each of these things is the same.
                    27
In this case, it is   C   or 27x26/2 or 351.
                        2
This also generalizes easily, e.g. dividing 30 apples among 5 can be
     34
done   C    ways.
         4
Incidentally, I first came across this problem when studying quantum
mechanics, which was the last place I expected to see combinatorics.
___________________________________________________________________
Tim Adam, B.Sc./B.E.(Elec) student, Melbourne University, Australia
Ph: (03) 807 3279   E-mail: tmadam@ee.mu.oz.au
Newsgroups: rec.puzzles
From: richard@skaro.demon.co.uk (Richard Develyn)
Subject: No subject
Organization: skaro
Date: Tue, 26 Jan 1993 14:36:30 +0000

Probability puzzle
This puzzle sounds similar to the two children one discussed here 
already but I've never heard a satisfactory explanation:

You and two other people (call them B and C) are locked, in separate 
cells, in a prison.  You are told that two of you are to be executed. 
So you calculate your chances of survival to be 1 in 3.

The gaoler wanders round and you say to him that, since clearly at 
least one of the two other chaps is going to die, he wouldn't be 
giving anything away by telling you which one. He does - say B. Now, 
amazingly, you calculate your chances of survival as 1 in 2 since it 
is clear that either C or you will be the other victim.

So, you think to yourself, you fooled the gaoler. His information was 
(somehow) able to improve your chances of survival. Then you wake up 
and realise that you never had that conversation at all. However, you 
pretend that you do have this conversation. Whichever other prisoner 
he tells you is for the chop your chances are still 1 in 2. So in fact 
your chances of survival were 1 in 2 all along ...

Errrmmmm.

Richard
--

Richard Develyn from Hastings, Sussex, England ( rad@cix.compulink.co.uk ).
Software engineer (datacomms) for Cray Network Systems. Married to Caroline.
Baby daughter Sophie (b. 3/11/92). Hobbies: Dr Who, FRPG, SF, Curry,
quality computer games, philanthropic discussions.
From: adculha@afterlife.ncsc.mil (Andrew Culhane)
Newsgroups: rec.puzzles
Subject: Re: 27+2=30
Date: 26 Jan 93 16:51:54 GMT
Organization: The Great Beyond

In article <1k2sfkINN9pf@sipi.usc.edu> haddadi@sipi.usc.edu (Navid Haddadi) writes:
>Here is a very old puzzle:
>Three men rent a room for $30. The inn keeper decides that he has
>over charged them and gives the bellboy $5 to give back to the men.
>The bellboy decides to keep $2 and give each man $1. 
>So, each man has paid $9 (3x9=27) plus the $2 that the boy kept.
>Hence, 27+2=30.
>
>It is actually more funny than silly!

I am sure you'll get a million replies, but I am  posting because for
some bizarre reason, I couldn't get this old one out of my head as I
fell asleep last night.

The $2 that the bellboy kept is part of the $27, so it makes no
sense to add it to a sum it's already included in.

You can say: $30 paid = $25 charged + $3 refunded + $2 stolen, or
              $27 paid = $25 charged + $2 stolen.

--- adc
Newsgroups: rec.puzzles
From: karr@cs.cornell.edu (David Karr)
Subject: Re: No subject
Organization: Cornell Univ. CS Dept, Ithaca NY 14853
Date: Thu, 28 Jan 1993 20:02:13 GMT

In article <93027.161640RVESTERM@vma.cc.nd.edu> <RVESTERM@vma.cc.nd.edu> writes:
>you, eduardo, and annette are prisoners, and the warden says,
>"two of you, chosen at random, are going to be executed tomorrow."
>clearly, you have a 1/3 chance of living.  at least one of annette
>and eduardo will die, so you ask the warden to tell you the name of
>a person, besides yourself, who will be executed.  "annette's gonna
>bite it," he says.
>
>now, what's the chance of your survival? it is the chance that eduardo
>will be executed, given that annette will be executed.  that is equal
>to the chance that both eduardo and annette will be executed, divided
>by the chance that annette will be executed.  that's 1/3 divided by
>2/3.  that's 1/2.
 ^^^

The 2/3 should be 1, since the warden has told you that Annette *will*
be executed.  So your odds of survival compute to 1/3.  No paradox.

The way you have set this up, it is *exactly* analogous to the Monty
Hall puzzle.

-- David Karr (karr@cs.cornell.edu)
From: micha@prosun.first.gmd.de (Michael Nitsche)
Newsgroups: rec.puzzles
Subject: Re: Need puzzle help: eye colour enigma
Date: 26 Jan 93 17:05:04 GMT
Organization: GMD-FIRST, D-1000 Berlin 10


|> > There is an island,on which there are 100 blue eyed people and 100 brown
|> > eyed people.  The people, however, do not know the number of people with
|> > each eye colouring.  No-one knows their own eye colour, as there is no means
|> > of reflection, and no-one will tell anyone else their eye colour, since as
|> > soon as someone knows their own eye colour, they kill themselves 24 hours
|> > later. 
|> > Once every 100 years, a green-eyed guru speaks to the populus, and today's
|> > the day (quite by chance).  S/he stands on a rise, looking out over all these
|> > people (who don't know their own eyecolour), and announces:  "I can see
|> > someone with blue eyes"
|> > 
|> >     Who kills themselves, and when???

Unfortunately, I have just joined the group so I did not catch the original article.
But the solution to the puzzle is ... <SPOILER>




































Suppose there was just one blue-eyed person. This person can only see brown-eyed people.
If the guru says "I can see someone with blue eyes", this person knows immediately that s/he has blue eyes and kills himself on the next day (call this day 1 AG - "after guru").

All the other people (with brown eyes) can tell from the suicide of the blue-eyed person
that this person has not seen anybody else with blue eyes (otherwise s/he would not have been able to conclude that s/he has blue eyes and killed himself on day 1 AG). So all brown-eyed people know on day 1 AG that they have brown eyes and kill themselves on day 2 AG.


If there are two people with blue eyes, each of them can see one person with blue eyes.
If this person does not kill himself on day 1 AG (s. above), each of them knows that there must be someone else with blue eyes. Therefore each of them knows on day 1 AG that s/he
has blue eyes and kills himself on day 2 AG.

The brown-eyed people can tell from the double-suicide on day 2 AG that each blue-eyed person
has seen only one other blue eyed person. Thus they know on day 2 AG that they have brown eyes and kill themselves on day 3 AG.

...

If there are 100 blue-eyed people, each of them can see 99 people with blue eyes. If these people do not commit suicide on day 99 AG, there must be someone else with blue eyes. Thus every blue-eyed person knows his eye colour on day 99 AG and kills himself on day 100 AG.

The brown-eyed people can tell from the 100-fold suicide on day 100 AG that there were exactly 100 people with blue eyes and that they all have brown eyes. Therefore they commit collective suicide on day 101 AG.


Note: The number of people with brown eyes does not matter in this tragedy.


Enjoy your life and eye colours -

Michael


============================================================
Michael Nitsche			Email: micha@first.gmd.de
GMD FIRST
Rudower Chaussee 5
Gebaeude 13.7
O - 1199 Berlin
============================================================

Newsgroups: rec.puzzles
From: nevin@apple.com (Nevin ":-]" Liber)
Subject: Re: RAAARRGGHH!!!!!  not again! (was:Re: Are you sure?)
Date: Thu, 28 Jan 1993 04:07:07 GMT
Organization: Apple Computer, Inc.
Followup-To: rec.puzzles

In article <1993Jan26.095218.17387@cbfsb.cb.att.com>,
cooper@cbnewsg.cb.att.com (Ralph 'Hairy' Moonen) wrote:
>Try this analogy, and you'll see
> what's wrong with your answer.
> 
> You are throwing 2 consecutive dice. The first one turns up a six. What is
> the chance of the second also being a six. It's easy to see that because dice
> have no memory, the chance is also 1/6. Now, following your line of reasoning,
> there are 36 different ways to throw the dice. Because 1 six already has
> been thrown this leaves 11 combinations, one of which is a double six.
> So, according to you, you only have 1/11 chance of throwing a second six.
> Clearly this is dead wrong.

Yes, your analogy is dead wrong.  The analogy for the original problem is:

You are throwing two dice, and at least one of them turns up a six.  What
are the chances that you rolled a total of twelve?  If you believe that the
answer is 1/6 and not 1/11, please come over and bet me anytime. :-)
NEVIN ":-)" LIBER, RISC Meanie, Mac System Software
 email:     nevin@apple.com        paper:  Apple Computer, Inc.
 voice:     (408) 974-MIX1                 20525 Mariani Avenue, MS: 81-GC
 AppleLink: BADENOV                        Cupertino, CA 95014
From: jay@tweekco.uucp (Jay Whitley)
Newsgroups: rec.games.chess
Subject: Drugs in Chess?
Date: 22 Jan 93 05:14:01 GMT
Organization: Tweek-Com Systems BBS, Moraga, CA (510) 631-0615

I've read allegations about drugs in chess (allegations about
Karpov in K-K World Championship, etc.)  Should drug use be
banned from chess play as it is in athletic events? Should there
be drug testing?  Or, is this even an issue in chess?
Newsgroups: rec.games.chess
From: palane@iastate.edu (Paul A. Lane)
Subject: Re: ClassC to B ratings question. provisional? etc?
Organization: Iowa State University, Ames IA
Distribution: usa
Date: Tue, 26 Jan 1993 06:29:56 GMT

In <1993Jan25.194319.22682@news.weeg.uiowa.edu> elowther@news.weeg.uiowa.edu (Edward Lowther) writes:

>   Beating a 7XX rated (10 year old) as my 20th game doesn't make the
>thing go down, does it? I hope not.

Well, it probably will. The game would count as 11XX towards your average
of the first twenty games. Assuming this is appr. 400 points below your
rated play, this would cost you ~20 rating points. Don't sweat it. The
win should get you into stronger brackets where you hopefully move up.

> My question is basically: Does a C-player about to be B'd get it if
>one of the three games that could bump him up is still provisional, and
>400+700 looks to me to bring it down a little. (?)

I wouldn't worry too much about exactly when you'll make it. Assuming you're
playing well, you'll make class B. It took me a year or so of rated play
before I got a little philosophical about matters. I established a provi-
sional rating a shade under 1500 and was confident of moving up. My next
three tournaments were all disasters and I dropped down to 1419.

Talk about discouraged. Here I'd been diligently studying and my rating was
going DOWN! Fortunately, I kept working (My System was a big help) on my
game and assumed good results would come. My performance rating has been
quite strong the last several tournaments and I've recovered my drop and
more.

The storal of my mory: (with apologies to the Capital Steps) don't worry 
so much about the class ratings. If you're playing class B chess (or better),
the rating points will come. 

>	Aha! Faked you out! I've been working on the French! 1.e4 e6
>2.d4 d5 3.e5 c5 4.c3 Qc7 (?!)   and since this is mysterious, and I am
>now smirking, he believes I know what I am doing.  This is the wrong 
>square, sure, but it was close enough at the time.  N-e7-f5 was accomplished,
>and I got the tempo back sort of. Later, when I looked like I was losing, I
>offered a draw.  This made him think he had a quicker win than he really
>had, so blew it.  *I don't deserve it!* grin, grin, grin. Same Bishop
>endgame won by Black!  

3. Nc3 Have at you!

Paul
From: maillet@moose.usmcs.maine.edu (Edward G. Maillet)
Newsgroups: rec.games.chess
Subject: Fish Analysis
Date: 22 Jan 1993 19:01:12 -0600
Organization: UTexas Mail-to-News Gateway
NNTP-Posting-Host: cs.utexas.edu


(Ok. Here it is. My one shot at immortality and I'm stuck with
  an ASCII board at 2400 baud)
 [White vs. scratchy --- Wednesday January 20, 09:11 PM EST, 1993]
 [Unrated blitz match, initial time: 10 minutes, increment: 0 seconds.]
 1. e4 c5 2. d4
(Smith-Morra Gambit. The only reply to the silician I know. )
 2. ... cxd4 3. c3
(Well Well Scratchy is out of its book.)
 3. ... dxc3 4. Nxc3 Nc6 5. Nf3 e6 6. Bg5 Be7
(I was hoping for Nf6 here to avoid exchanging Bishops)
 7. Bxe7
(To keep tempo? Pulling the bishop back loses time.)
 7. ... Ngxe7 8. Bc4 O-O 9. O-O d6
(Now I start thinking.)
 10. Rc1 a6 11. a4
(Preventing b5)
 11. ... b6 12. e5?
(I want to get the Q's off the board, hoping for Nxe5 13. Nxe5 e5
14. Qxd8 Rxd8 15. Rfd1 Rxd1 16. Rxd1 giving me the file.)
 12. ... dxe5 13. Qxd8 Rxd8 14. Rfd1 Bb7 15. Ne4 Na5
(Hmm. No big deal.)
 16. Nd6 Bxf3 17. gxf3 Nf5 18. b4 Rxd6 19. Rxd6??
(ASCII boards really suck. 19. bxa5 leaves me ok. I was thinking
 19. Rxd6 Nxd6 20. bxa5 oh well.)
 19. ... Nxc4 20. Rc6
(Ok. I can get the knight or the win.)
 20. ... b5
(NOT! All hope now vanishes.)
 21. axb5 axb5
(ok now I'm stuck down 2 N's to an R with an ASCII board. I'm going to feel
  like a pin cushion.)
 22. Rc5 Nd4 23. Kg2?? h6!
(not 23. ... Nb3? 24. Rxb5 Nxc1 25. Rc5!! Winning a N+P for an R)
 24. Rc7 Ra4 25. Rb1 g5 26. Rc8+
(Not much else to do)
 26. ... Kg7 27. Kg3 Nd2 28. Rbc1?? Ne2
(Mommy)
----- Ed Maillet (White)
ip05872@portland.maine.edu
Werner Heisenberg should read 101 uses for Schrodinger's DEAD cat.
From: jeff@econBerkeley.EDU (Jeffrey C. Ely)
Newsgroups: rec.games.chess
Subject: Re: touch-move etiquette
Date: 28 Jan 1993 00:14:02 GMT
Organization: Econometrics Laboratory, U. C. Berkeley
Distribution: usa
NNTP-Posting-Host: emily9.berkeley.edu

Here's a subject I've never seen addressed in this recurring thread:  Suppose
you are promoting a pawn and you grab a piece for promotion.  At what point
do you lose the option to change your mind about which piece to promote to?
Is it after you touch a particular piece, or after that piece touches the
board, or after you release it?

+++++++++++++++++++++++++++++++++|+++++++++++++++++++++++++++++++++++++++++
Jeff Ely                         |    "He said the Sun's not yellow...  
Department of Economics          |     It's Chicken!" 
UC Berkeley                      |
jeff@econ.berkeley.edu           |
From: drchip@cup.portal.com (MYRON A LIEBERMAN)
Newsgroups: rec.games.chess
Subject: Re: Clubs in S.F. Bay Area ?ok
Date: Sun, 24 Jan 93 00:57:36 PST
Organization: The Portal System (TM)

In SF try the Mechanics' Institute Chess Club.
Newsgroups: rec.games.chess
From: hyatt@cis.uab.edu (Robert Hyatt)
Subject: Re: Parallel Chess Programs?
Organization: University of Alabama at Birmingham
Date: Mon, 25 Jan 1993 22:07:16 GMT

In article <C1Errs.DC@dcs.ed.ac.uk> pds@epcc.ed.ac.uk (Patrick Surry) writes:
>Can anyone give me any information on chess programs that have been
>implemented on parallel machines and/or techniques for same?  We are 
>interested in developing a very simple such program as a learning
>experience.
>
>Thanks for your help,
>Patrick
>
>---------------------------------------------------------------------------
> Engineers  think that theory  approximates reality | Mathematicians never
> Physicists think that reality approximates theory  | make the connection
>---------------------------------------------------------------------------
> Patrick Surry, JCMB 2254, Edinburgh, Scotland   e||)   Edinburgh Parallel  
> EMail: pds@epcc.ed.ac.uk  Tel: (031) 650-5960   c||c   Computing Centre    
>---------------------------------------------------------------------------
>
>  


The ones I'm familiar with:

1.  Cray Blitz.  Runs on shared memory parallel machines like the ones from
Cray Research.  Several publications describe it's parallel search.

2.  Sun Phoenix.  Runs on a distributed network of sun workstations and does
not require shared memory, but does need fast network interconnections like
ethernet or better.  Again, several publications exist.  Jonathan Schaeffer
is the contact here, although they have stopped work on the chess program
to pursue development on Chinook...

3.  Deep Thought/Deep Blue.  This is based on a symbiosis of a fast host
computer with multiple special-purpose chess processors to assist it in
carrying out the tree search.  Might not be as applicable to your needs.

4.  CalTech developed a chess program for the hypercube machine.  Don't recall
the name, but it was designed for a specific architecture and might not be
applicable to your needs.

5.  Bert Wendroff at Los Alamos worked on a parallel version of his LaChex
program, but later discontinued the parallel search due to the difficulties
of finding time on a parallel supercomputer to play chess...

6.  Monty Newborn tried a couple of parallel search strategies, and again there
are publications to describe his work (ostrich).

As a final note, "beware" of trying to play around with parallel chess search
strategies.  They are both addictive and difficult to debug.

-- 
!Robert Hyatt                    Computer and Information Sciences   !
!hyatt@cis.uab.edu               University of Alabama at Birmingham !
From: ralf@ark.abg.sub.org (Ralf Stephan)
Newsgroups: rec.games.chess
Subject: Some chess program/computer news
Date: 25 Jan 93 13:17
Organization: Not Very Ltd.

Hi, I thought I would mention some news that I have out of the new MODUL:

- Ed Schroeder is rumored to be working on a PC version of the Chessmachine
  program  [With this, all well-known commercial chess programmers would
  be present in the PC market].

- The first PC program to feature the Fischer clock is HIARCS which is
  available in Britain for BP 70, and is estimated at or above the
  RexChess level.

- G"oran Grottling, the maintainer of the Swedish Computer Chess Rating List,
  has opened a BBS:  Grottan BBS (Sweden+31992301, V.32bis)
  Available:  news, mail, games, programs, tools etc.

- The magazine MODUL is specializing on PC programs.  Chess computers are dead.

ralf
--
************************************
One program's worth a thousand words.
Newsgroups: rec.games.chess
From: rryan@panix.com (Rob Ryan)
Subject: Re: If Short-Timman Match Ties
Organization: Panix, NYC
Date: Thu, 21 Jan 1993 08:21:35 GMT

In <1jknl1INNc2b@elroy.jpl.nasa.gov> tjt@Jpl.Nasa.Gov (Tim Thompson) writes:

>  Someone suggested surprise that something so important as a candidates match
>would be settled by mere speed chess. Remember, when Kasparov played in the
>candidates for the first time, some years back, one of his opponents was the
>venerable ex world champion Vassily Smyslov. Smyslov made it be tying his match,
>and tie-break games with Robert Hubner. Finally, it was settled by a roulette
>wheel! Smyslov chose red, Hubner was black, and on the first spin the ball
>landed in 00 (no color!). They had to spin the wheel again for the ball to
>land in red, giving the match to Smyslov. How's that for settling a candidate's
>match?

Well, if the speed chess playoff rounds are tied too, they're going to resort
to drawing lots for the Timman-Short match as well.
-- 
Rob Ryan
    rryan@panix.com
Newsgroups: rec.games.chess
From: richard@skaro.demon.co.uk (Richard Develyn)
Subject: Re: Gunderam Attack references sought
Organization: skaro
Date: Tue, 26 Jan 1993 13:56:35 +0000

The Opening Repertoire for the Attacking player by Raymond Keene and 
somebody else has a short section on this since this is the variation 
they recommend.
Richard
--

Richard Develyn from Hastings, Sussex, England ( rad@cix.compulink.co.uk ).
Software engineer (datacomms) for Cray Network Systems. Married to Caroline.
Baby daughter Sophie (b. 3/11/92). Hobbies: Dr Who, FRPG, SF, Curry,
quality computer games, philanthropic discussions.
From: fry@zariski.harvard.edu (David Fry)
Newsgroups: rec.games.chess
Subject: Re: CHESS SAVANTS?
Date: 21 Jan 93 14:37:31 GMT
Organization: Harvard Math Department

In article <2017@spam.ua.oz> ahanysz@spam.ua.oz (Alexander Hanysz) writes:
>In article <Jan.15.16.48.50.1993.10652@riches.rutgers.edu> rhoads@riches.rutgers.edu (Glenn Rhoads) writes:
>>The phrase "idiot savant" is no longer used by the medical community.
>>The currently accepted term is "autistic savant".  IMO, this is a
>>better and more accurate term.  "Autistic" basically means that the
>>person is living in their own private world.  They can't reach out to
>>the real world and no one can reach into their's.  "Savant" means that
>>they are amazingly skilled in one single extremely narrow area (e.g.
>>one well know savant can't add or subtract yet can immediately tell
>>you the day of the week that any date in history or the future falls
>>on).  Hence, the term "autistic savant".
>
>
>The current Australian junior (under 18) chess champion, Trevor Tao,
>is autistic.  However, I'm not sure that he meets your definition of
>"savant."  He's also a very good pianist.
>
>								Alex.

There clearly are levels of autisism.  The actress Daryl Hannah, for
instance, was determined to be "mildly autistic" when she was young,
but I don't think anyone would confuse her for Rainman.  So, "how
autistic" is Tao?

David Fry                                  fry@math.harvard.edu
Division of Applied Sciences               fry@huma1.bitnet
Harvard University                      ...!harvard!huma1!fry
Cambridge, MA  02138