HDTenEightyP/NetNews huggingface dataset:
From: kanad@quip.eecs.umich.edu (Kanad Chakraborty)
Subject: Re: Are you sure?
Organization: University of Michigan EECS Dept., Ann Arbor
Date: Tue, 26 Jan 1993 20:44:22 GMT

In article <6670016@hplsla.hp.com> barryg@hplsla.hp.com (Barry Gunn) writes:
>>>You meet the daughter of a friend of yours on the street.  You know that your
>>>friend has two children.  You think to yourself, "Ignoring the occurrence of
>>>twins, and sex-linked differences in birth rates and infant mortality, what
>>are
>>>the odds of this girl's sibling also being a girl?"
>>>-----------------+-------------------------------
>>Two child families are uniformly distributed between MM,MF,FF,FM, in birth
>>order.  Again, all four possibilities are equally likely.  Stop here.  Make
>>sure you believe that.
>>
>>Now, since at least one is F, the MM drops out, leaving MF, FF, FM, so that
>>there is only a one third chance that the sibling is a girl.
>
>But you meet the F on the street. So MF and FM are the same in this case
>(but not the way the problem is usually stated). I say 50%.

I disagree. I made this mistake once myself and promptly realized the flaw.
Why don't you consider this metaphor : you have these teeming
billions of sibling-pairs in the Earth (yeah, I mean all continents,
islands, places hitherto undiscovered or unknown, etc. etc. taken
together ad nauseam :-) ) ?  Now, it's quite easily seen that FF 
pairs comprise only 25 % of _this_ population (assuming that the
birth events of a pair of siblings are independent, thereby precluding 
identical twins, etc.). 50 % of this population will comprise MF
sibling pairs, and the remaining 25 %, MM pairs.

Now, you the witness of one of a pair of siblings, are a Martian
and have just floated down on the earth from Mars on a spaceship,
on a special invitation from Presidents Clinton and Yeltsin,
and see one female member of a pair of siblings, who has been sent
by her Dad to receive you.  You have had numerous inter-planetary 
conversations with her Dad (mostly on new and exciting ways of
proving that P equals NP :-) ), and know that he has two children, 
but you've never asked him their sexes. Now without any other info, 
it's a fair assumption that you'll encounter sibling pairs on the Earth
in proportion to their relative frequencies of occurrence.  Hence, 
the female sibling you encounter is twice as likely to be a part of a
mixed sex pair than of an FF pair.  Hence, the other sibling being a
female has probability 1/3.

Hope it helps.

Kanad
Newsgroups: rec.puzzles
From: joel@math.toronto.edu (Joel Chan)
Subject: Re: Irrational numbers
Organization: Department of Mathematics, University of Toronto
Date: Tue, 26 Jan 93 23:46:50 GMT

In article <19723.2b6495ca@ecs.umass.edu> padmanab@ecs.umass.edu writes:
>Here is an interesting puzzle concerning 
>irrational numbers: 
>
>Can you find two IRRATIONAL NUMBERS P and Q such that 
>
>                    Q 
>                   P  =  rational? 
>
>HAVE FUN!

Let P and Q both be equal to sqrt(2).

Is P^Q rational?  If it is, we're done.

If it isn't then take (P^Q)^R, where R = sqrt(2).


Joel
-- 
Joel Chan, Department of Mathematics	  	 joel@math.toronto.edu
Toronto Blue Jays: 1992 World Series Champions
"History: Those who ignore it are condemned to repeat it.  Math, too."
				    -From the comic strip "Betty"
Newsgroups: rec.puzzles
From: stein@hal.nta.no (Stein Kulseth)
Subject: Re: Irrational numbers
Organization: Norwegian Telecom Research
Date: Tue, 26 Jan 93 10:44:16 GMT

In article <19723.2b6495ca@ecs.umass.edu>, padmanab@ecs.umass.edu writes:
|> Here is an interesting puzzle concerning 
|> irrational numbers: 
|> 
|> Can you find two IRRATIONAL NUMBERS P and Q such that 
|> 
|>                     Q 
|>                    P  =  rational? 
|> 
|> HAVE FUN!
|> 
|> -Prasad Padmanabhan
|> Dept. of ECE
|> University of Massachusetts
|> Amherst MA 01003

e and ln2
-- 
stein.kulseth@nta.no (Norwegian Telecom Research)
   'When murders are committed by mathematics, they can be solved by
   mathematics. Most of them aren't, and this one wasn't'
   - Nick Charles (Dashiell Hammett's "The Thin Man")
Newsgroups: rec.puzzles
From: karr@cs.cornell.edu (David Karr)
Subject: Improper attribution
Organization: Cornell Univ. CS Dept, Ithaca NY 14853
Date: Tue, 26 Jan 1993 16:29:07 GMT

In article <1k3f3hINN29k@gap.caltech.edu> carl@SOL1.GPS.CALTECH.EDU writes:
>In article <1993Jan26.115545.11556@eng.cam.ac.uk>, cmh@eng.cam.ac.uk (C.M. Hicks) writes:
>=karr@cs.cornell.edu (David Karr) writes:
>=
>=>>You meet the daughter of a friend of yours on the street.  You know
>=>>that your friend has two children.  You think to yourself, "Ignoring
>=>>the occurrence of twins, and sex-linked differences in birth rates
>=>>and infant mortality, what are the odds of this girl's sibling also
>=>>being a girl?"

Just for the record, I never wrote the above paragraph.  I quoted it
merely because I disliked the wording, and now two people (Hicks and
Lydick) have posted my name above it for no good reason at all.  Sigh.
Cut it out, guys!

-- David Karr (karr@cs.cornell.edu)


Newsgroups: rec.puzzles
From: karr@cs.cornell.edu (David Karr)
Subject: Re: Are you sure?
Organization: Cornell Univ. CS Dept, Ithaca NY 14853
Date: Mon, 25 Jan 1993 14:57:59 GMT

In article <1993Jan22.131719.36@janus.arc.ab.ca> morgan@arc.ab.ca (Sean Morgan) writes:
>You meet the daughter of a friend of yours on the street.  You know
>that your friend has two children.  You think to yourself, "Ignoring
>the occurrence of twins, and sex-linked differences in birth rates
>and infant mortality, what are the odds of this girl's sibling also
>being a girl?"

Which of my friends did you have in mind?  Then I can tell you whether
the odds are 0% or 100%.

-- David Karr (karr@cs.cornell.edu)



Newsgroups: rec.puzzles
From: lbaum@atc.boeing.com (Larry Baum)
Subject: Re: Irrational numbers
Organization: Boeing Computer Services
Distribution: usa
Date: Tue, 26 Jan 1993 18:16:58 GMT

In article <19723.2b6495ca@ecs.umass.edu> padmanab@ecs.umass.edu writes:
>Here is an interesting puzzle concerning 
>irrational numbers: 
>
>Can you find two IRRATIONAL NUMBERS P and Q such that 
>
>                    Q 
>                   P  =  rational? 
>
>HAVE FUN!
>
>-Prasad Padmanabhan
>Dept. of ECE
>University of Massachusetts
>Amherst MA 01003
>

Since e**(ln x) = x, P = e, Q = ln r, will suffice for any rational.

Left to the reader: show ln r is not rational.

Newsgroups: rec.puzzles
From: cooper@cbnewsg.cb.att.com (Ralph 'Hairy' Moonen)
Subject: Apology
Organization: AT&T
Date: Thu, 28 Jan 1993 10:39:42 GMT


I apologise to whoever I have flamed for claiming the answer to be 1/3 in
the question *At least one of the two kids of a family is a girl, what is
the chance that both are girls*. However, the answer to the question
*Given that one of the two kids of a family is a girl, what is the chance
that the other is also a girl* stays 1/2 .

The dice problem I had right all along. 

--Ralph
From: J.Theodore.Schuerzinger@dartmouth.edu (J. Theodore Schuerzinger)
Newsgroups: rec.puzzles
Subject: Re: sphere packing
Date: 27 Jan 93 02:39:16 GMT
Organization: Dartmouth College, Hanover, NH
X-Posted-From: InterNews1.0a5@newshost.dartmouth.edu

In article <1993Jan26.235433.18005@cs.ucla.edu>
byron elbows writes:

> I need help on a sphere packing question.  Suppose you have a white ping
> pong ball, and 13 red ones, all the same size.  Can you glue all of the red
> ping pong balls to the white one?  In other words, is it possible to place
> 13 unit spheres around one unit sphere, so that each of the 13 is touching
> the central sphere, and none of the 13 intersect each other?
> 
> It is a simple matter to do it with 12.  Simply place the spheres at the
> corners of an icosahedron centered at the center of the white ping pong ball.
> It turns out this leaves some extra room for spheres to be moved around, but
> is it possible to move them around so that another sphere can be squashed
> in there?

You're asking a question about the 'kissing number'; that is, the
greatest number of objects that can be touching another object of the
same size.  For two dimensions (ie. circles), the kissing number is 6,
and for three dimensions (spheres -- the question you ask), it's been
proven that the kissing number is 12.  Therefore, there is no way to
move those twelve spheres to make a 13th one touch the center sphere. 
Sometime within the last year (sorry I don't have the exact date!)
Scientific American ran a piece about the kissing number in its math
column.


--Ted Schuerzinger
email: .zed@Dartmouth.EDU
"I should have realized it would be bad vodka when all the label said
was 'Russian Vodka'."
From: rmurphy@usc.edu (Bob Murphy)
Newsgroups: rec.puzzles
Subject: Scrabble
Date: 27 Jan 1993 01:31:09 -0800
Organization: University of Southern California, Los Angeles, CA
Distribution: na
NNTP-Posting-Host: aludra.usc.edu

Lately, I have been trying to find large scores in a single turn
for the game of Scrabble.  My highest so far is 1569.  I was 
curious if anyone has seen larger scores than this.  Obviously,
I had to set this up.  I think my largest score for a single turn
in a REAL game is between 100 and 200.

                    Bob Murphy (rmurphy@aludra.usc.edu)
From: dlytle@OAVAX.CSUCHICO.EDU (Don Lytle)
Newsgroups: rec.puzzles
Subject: The Association for the Study of Play conference
Date: 21 Jan 93 20:53:07 GMT
Reply-To: dlytle@OAVAX.CSUCHICO.EDU
Organization: California State University, Chico
NNTP-Posting-Host: oavax.csuchico.edu


                 *****   ANNOUNCEMENT AND CALL FOR PAPERS   *****

                             TASP 1993 - St. Paul, MN
                     The Association for the Study of Play
      April 22 - 24, 1993 * The St. Paul Hotel * St. Paul, Minnesota

   The Association For The Study of Play (TASP) will hold its 1993 annual meetings in St. Paul, Minnesota.  The conference will begin Thursday and continue   until Saturday, April 24. There will be featured speakers, playshops, and forums for the discussion and presentation of   research papers on all aspects of play research, theory, performance and behavior.
    For the past twenty years TASP conferences have provided  a  mechanism by  which  researchers in diverse fields have the opportunity to share ideas  and  interact  in  a friendly and collegial atmosphere.
   Papers and proposals for panel sessions or tutorials related to the broad  study of play are invited.  Sessions include, but are not limited to:
 - Humor, laughter
 - Computer and cyperspace play
 - Folklore
 - Children's play behavior
 - Cross-cultural play
 - Body work and play art
 - Performance 
 - Anthropology of festive play
 - Sport
 - Literary playfulness

Deadline for submission of abstracts is February 5, 1993.

Send abstracts (100 word maximum), audio-visual needs, and registration fees  ($60 professional and $20 student made payable to TASP) to:

Dr. Don Lytle
Department of Physical Education
California State University, Chico  95929-0330. 
Bitnet/E-Mail: DLYTLE@OAVAX.CSUCHICO.EDU; FAX: 916 898-4932; 
Phone: {916} 898-6617 or 898-6373 {message}
From: radcliff@csd4.csd.uwm.edu (David G Radcliffe)
Newsgroups: rec.puzzles
Subject: Re: sphere packing
Date: 28 Jan 1993 02:12:08 GMT
Organization: UW-Milwaukee Math Department
NNTP-Posting-Host: 129.89.7.4
X-Newsreader: TIN [version 1.1 PL8]

From the Feb. 1992 issue of Scientific American:

          Kissing Numbers

Dimension    Lower limit   Upper limit
   1*            2             2
   2*            6             6
   3*           12            12
   4            24            25
   5            40            46
   6            72            82
   7           126           140
   8*          240           240
   9           306           380
  10           500           595
  11           582           915
  12           840         1,416
  13         1,130         2,233
  14         1,582         3,492
  15         2,564         5,431
  16         4,320         8,313
  17         5,346        12,215
  18         7,398        17,877
  19        10,688        25,901
  20        17,400        37,974
  21        27,720        56,852
  22        49,896        86,537
  23        93,150       128,096
  24*      196,560       196,560

REFERENCES (from the Sci. Am. article)

The Problem of the Thirteen Spheres. John Leech in Mathematical Gazette,
  Vol. 40, No. 331, pages 22-23; February 1956
Sphere Packings, Lattics and Groups.  John Horton Conway and Neil J. A.
  Sloane.  Springer-Verlag, 1988.
Sphere Packings and Spherical Geometry--Kepler's Conjecture and Beyond,
  preprint.  Wu-Yi Hsiang.  Center for Pure and Applied Mathematics,
  University of California, Berkeley, July 1991.
--
David Radcliffe                                
radcliff@csd4.csd.uwm.edu            
Newsgroups: rec.puzzles
From: dwj@iedv6.acd.com ( Dan Johnson         )
Subject: Re: Irrational numbers
Organization: Applied Computing Devices, Inc., Terre Haute IN
Date: Tue, 26 Jan 1993 23:16:15 GMT

In article <19723.2b6495ca@ecs.umass.edu> padmanab@ecs.umass.edu writes:
>Can you find two IRRATIONAL NUMBERS P and Q such that 
>
>                    Q 
>                   P  =  rational? 
SPOILER:

P = e, Q = ln 2
-- 
Daniel W. Johnson                  Applied Computing Devices, Inc.
Home: 71520.367@CompuServe.COM     Work: dwj@iedv1.acd.com
      DanielJ13@aol.com                  39 25 02 N / 87 19 55 W
                - this space unintentionally left blank -
Newsgroups: rec.puzzles
From: acheng@ncsa.uiuc.edu (Albert Cheng)
Subject: Re: Are you sure?
Originator: acheng@shalom.ncsa.uiuc.edu
Organization: Nat'l Ctr for Supercomp App (NCSA) @ University of Illinois
Date: Tue, 26 Jan 1993 17:25:16 GMT


In article <1993Jan25.115908.41@janus.arc.ab.ca>, morgan@arc.ab.ca (Sean Morgan) writes:
>(Some of my mail says "not again", and some says "please post a solution".
> Since you can't please all of the people all of the time...)
>
>Two child families are uniformly distributed between MM,MF,FF,FM, in birth
>order.  Again, all four possibilities are equally likely.  Stop here.  Make
>sure you believe that.

Okay, got it.

>Now, since at least one is F, the MM drops out, leaving MF, FF, FM, so that
>there is only a one third chance that the sibling is a girl.

But what are the chance of you meeting one of these three pairs?  Their
birth chance does not imply your meeting chance.  Let me show it:

We are talking about two-kids families.  4 equal combinations but 8
possible kids, mm, MF, FM, ff.  Assume you have equal chance meeting
one of them.  But you are limiting your calculation ONLY if you meet a
girl, i.e. only if you meet the "F" of {FM,MF} or either "f" of "ff".
So, total four possible girls.  Half of them have a femal sibling, the
other half male sibling.  Thus the answer of your question is 0.5.

Nothing personal but here is a joke i remember reading the "Born Loser"
comic.  He figured the chance of boarding a plain having a bomb is
1 out of a million.  Having two bombs on the same plane should be
1 out of a trillion.  So, he decided to bring along a bomb when
he was reading to board it.
Newsgroups: rec.puzzles
From: morgan@spectra.com (Mike Morgan)
Subject: Re: A puzzle?, SPOILER ALERT !!
Organization: Spectragraphics Corporation
Date: Fri, 22 Jan 93 00:01:32 GMT

In article <1993Jan21.115427.29195@ida.liu.se> t91matfa@odalix.ida.liu.se (Mattias Fagerlund) writes:
>Well, lets see if this puzzle fits you.
>
>The solution seems me totally logical, but not every body might think so.
>You may ask me as many questions as you wish, but mail them to my person, 
>so you don't spoil it for the others.
>Questions will be answered with yes, no and irrelevant (most are).
>
>A man walks into a saloon and asks the bartender for a glass of water.
>The bartender, saying nothing, pulls out a shot-gun and points it at the man.
>-Thank you, the man says and leaves the bar.
>
>Question: 
>  What really happend? Why did the man say thank you (his goal WAS actually 
> achived) and leave?
>
>	-Mattias Fagerlund 
> 	t91matfa@und.ida.liu.se


Sorry, but this was too old to pass up, might even be in the FAQ.

The man had the hiccups, the bartender scared them away.
-- 
Michael L. Morgan 
morgan@spectra.com
Newsgroups: rec.puzzles
Subject: Are you sure?
From: morgan@arc.ab.ca (Sean Morgan)
Date: 22 Jan 93 13:17:18 MDT
Distribution: world
Organization: Alberta Research Council

You meet the daughter of a friend of yours on the street.  You know that your
friend has two children.  You think to yourself, "Ignoring the occurrence of
twins, and sex-linked differences in birth rates and infant mortality, what are
the odds of this girl's sibling also being a girl?"
-----------------+-------------------------------
Sean Morgan      |  ALBERTA  6815 - 8 Street N.E.
                 | RESEARCH  Calgary, AB, Canada
morgan@arc.ab.ca |  COUNCIL  T2E 7H7
From: sobelman@cco.caltech.edu (Steven M. Sobelman )
Newsgroups: rec.puzzles
Subject: Re: Turing Machines
Date: 26 Jan 1993 22:05:27 GMT
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Host: sandman.caltech.edu

ags@seaman.cc.purdue.edu (Dave Seaman) writes:

>In article <1k2ltpINNs62@gap.caltech.edu> carl@SOL1.GPS.CALTECH.EDU (Carl  
>J Lydick) writes:
>> In article <728019101.AA05890@csource.oz.au>,  
>Ben.White@f364.n633.z3.fidonet.org (Ben White) writes:
>> >Has anyone here ever constructed a universal turing machine? 
>> I tried once, but I ran out of memory :-).  Seriously, by imposing the
>> adjective "universal," you've required that the machine have infinite  
>memory.

>Wrong adjective. All turing machines, universal or not, have infinite  
>memory. 

Actually, all turing machines have infinitely extensible memory which, in some
implementations, is represented by a tape.  If you have the necessary splicing
skills and can provide tape (or memory) faster than a UTM can use it, you,
effectively, have infinite memory.

Building a UTM is a reasonably challenging task, I doubt it's been seriously
attempted.  I believe, however, that working non-universal TM's have been 
constructed.  They probably aren't very fast.


Steve
From: jgk@osc.COM (Joe Keane)
Newsgroups: rec.puzzles
Subject: 2-4-7 game
Summary: How to win this game?
Keywords: subtract
Date: 23 Jan 93 02:40:51 GMT
Article-I.D.: osc.5948
Reply-To: Joe Keane <jgk@osc.com>
Organization: Versant Object Technology
Moon-Phase: new

Here is a simple game played with two counters.  You name a number
(non-negative integer), and then your opponent names a different number.
These are the initial values of the two counters.

The general move is to decrease one of the counters by either 2, 4, or 7.
However, you can't make a counter negative.  Once a counter gets to 0 or 1, it
can't be changed any more.  The game is over when both counters are like this,
and the last person to move is the winner.

I claim there is a unique winning move.  What is it?  Show that after your
opponent names his number, the correct move is always to decrease the number
you named.  Also, explain what that move is based on what your opponent named.

If you've read _Winning Ways_ and you're going to use Nim-values to figure
this out, this puzzle is too easy for you.  I want the game to be explained so
that a small child could win.

--
Joe Keane, amateur mathematician
jgk@osc.com (uunet!amdcad!osc!jgk)
Xref: sparky rec.puzzles:8531 sci.math:18726 rec.games.misc:19344
From: dbh@doc.ic.ac.uk (Denis Howe)
Newsgroups: rec.puzzles,sci.math,rec.games.misc
Subject: Re: "Cut & Choose" for several players
Date: 25 Jan 93 16:08:22
Organization: Computing Department, Imperial College, London, UK
Distribution: world
NNTP-Posting-Host: wombat.doc.ic.ac.uk
In-reply-to: raph@panache.demon.co.uk's message of Fri, 22 Jan 1993 23:31:14 +0000

In article <727745474snz@panache.demon.co.uk> raph@panache.demon.co.uk
(Raphael Mankin) wrote:

>The general rule is that the player who divides does not choose.
>This negative feedback prevents bias in the divisions -- assuming
>that there are no collusions.  A Byznatine generals' solution would
>be much more complex.

A what?  What's a Byznatine (or even Byzantine) generals' solution?

>Player 1 divides the pile into a 1-portion and a (n-1)-portion.
>Player 2 decides whether he or player 1 gets the 1-portion.  Whoever
>gets it drops out.  The division continues with n-1 players and the
>(n-1)-portion.

That ensures that each person is satisfied with his own share but the
new version of the problem requires that each person be satisfied that
nobody else has a better portion.

Player 3 may think that the 1-portion was too big but he has no chance
to object according to the above algorithm.

I believe the problem is insoluble because anyone who is not involved
in making a division can always veto it.  There is thus no incremental
approach which successively excludes people from the decision making.
This means that everyone must simultaneously agree to all divisions
but that is just a restatement of the problem.
--
Denis Howe <dbh@doc.ic.ac.uk>
Who is the potter and who the pot?
From: robertw@informix.com (Robert Weinberg)
Newsgroups: rec.puzzles
Subject: Re: "Cut & Choose" for several players
Date: 26 Jan 93 20:26:08 GMT
Organization: Informix Software, Inc.

In article <727745474snz@panache.demon.co.uk> raph@panache.demon.co.uk (Raphael  
Mankin) writes:
> The general rule is that the player who divides does not choose. This
> negative feedback prevents bias in the divisions -- assuming that there 
> are no collusions.A Byznatine generals' solution would be much more
> complex.
> 
> Player 1 divides the pile into a 1-portion and a (n-1)-portion. Player 2
> decides wehther he or player 1 gets the 1-portion. Whoever gets it drops
> out. The division the continues with n-1 players and   the (n-1)-portion.

If the first division is unfairly large (obvious to all but myopic player 1 who cut  
it), player 2 reaps a bonus which will be judged as an unfair portion by all the  
remaining players.
--
+================================+================================+
|         Rob Weinberg           |  Workstation publications tech |
|   Email : robertw@informix.com |        Graphic designer        |
|   Voice : 415-926-6754         |     <imagine your ad here>     |
+================================+================================+
From: pscchris@ubvmsd.cc.buffalo.edu (Christopher Holoman)
Newsgroups: rec.puzzles
Subject: Re: What's this a diagram of?
Date: 28 Jan 93 15:06:00 GMT
Organization: University at Buffalo
News-Software: VAX/VMS VNEWS 1.41

In article <1k8lcgINNp6p@violet.csv.warwick.ac.uk>, strgh@csv.warwick.ac.uk (J E H Shaw) writes...
>In article <1993Jan28.001840.18529@sq.sq.com> dave@lsuc.on.ca (David Sherman) writes:
>>                 ----__i_i
>>                 |  %    /o -v\
>>                  \    % \_/   \
>>                  \`-----=,_--'/ o
>>
>>The above was constructed by a friend of mine.  He claims it's
>>a good ASCII representation of .... what?
>>
>>David Sherman
> 
>A dead one of these:-
>                       _
>                 o /,-- '=-----,\
>                   \   /-\ %    \
>                    \^- o/ _ __%  |
>                          ! !  ----
> 
>(shouldn't this be in the FAQ?)

Boy, this is an interesting group! Do people really ask that 
often how you kill a locomotive?

insert smilies as necessary.



>J.E.H.Shaw,  Department of Statistics,  |  JANET:  strgh@uk.ac.warwick

Chris
Newsgroups: rec.puzzles