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- Newsgroups: rec.puzzles,news.answers,rec.answers
- Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!spool.mu.edu!howland.reston.ans.net!europa.eng.gtefsd.com!uunet!questrel!chris
- From: chris@questrel.com (Chris Cole)
- Subject: rec.puzzles Archive (Instructions), part 01 of 35
- Message-ID: <puzzles/archive/Instructions_745653851@questrel.com>
- Followup-To: rec.puzzles
- Summary: This is part of an archive of questions
- and answers that may be of interest to
- puzzle enthusiasts.
- Part 1 contains the index to the archive.
- Read the rec.puzzles FAQ for more information.
- Sender: chris@questrel.com (Chris Cole)
- Reply-To: archive-comment@questrel.com
- Organization: Questrel, Inc.
- Date: Wed, 18 Aug 1993 06:04:18 GMT
- Approved: news-answers-request@MIT.Edu
- Expires: Thu, 1 Sep 1994 06:04:11 GMT
- Lines: 1545
- Xref: senator-bedfellow.mit.edu rec.puzzles:24989 news.answers:11509 rec.answers:1909
-
- Archive-name: puzzles/archive/Instructions
- Last-modified: 17 Aug 1993
- Version: 4
-
-
- ==> Instructions <==
- Instructions for Accessing rec.puzzles Archive
-
- INTRODUCTION
-
- Below is a list of puzzles, categorized by subject area. Each puzzle
- includes a solution, compiled from various sources, which is supposed
- to be definitive.
-
- EMAIL
-
- To request a puzzle, send a message to archive-request@questrel.com like:
-
- return_address your_name@your_site.your_domain
- send requested_puzzle_name
-
- For example, if your net address is "mickey@disneyland.com", to request
- "decision/allais.p", send the message:
-
- return_address mickey@disneyland.com
- send allais
-
- To request multiple puzzles, use several "send" lines in a message.
- Please refrain from requesting the entire archive via email. Use FTP.
-
- FTP
-
- The archive has been posted to news.answers and rec.answers, which are
- archived in the periodic posting archive on rtfm.mit.edu in the
- anonymous ftp directory /pub/usenet.
-
- Other archives are:
-
- ftp.cs.ruu.nl [131.211.80.17] in the anonymous ftp
- directory /pub/NEWS.ANSWERS (also accessible via mail
- server requests to mail-server@cs.ruu.nl)
- cnam.cnam.fr [192.33.159.6] in the anonymous ftp directory /pub/FAQ
- ftp.uu.net [137.39.1.9 or 192.48.96.9] in the anonymous ftp
- directory /usenet
- ftp.win.tue.nl [131.155.70.100] in the anonymous ftp directory
- /pub/usenet/news.answers
- grasp1.univ-lyon1.fr [134.214.100.25] in the anonymous ftp
- directory /pub/faq (also accessible via mail server
- requests to listserv@grasp1.univ-lyon1.fr), which is
- best used by EASInet sites and sites in France that do
- not have better connectivity to cnam.cnam.fr (e.g.
- Lyon, Grenoble)
-
- Note that the periodic posting archives on rtfm.mit.edu are also
- accessible via Prospero and WAIS (the database name is "usenet" on port
- 210).
-
- CREDIT
-
- The archive is NOT the original work of the editor (just in case you were
- wondering :^).
-
- In keeping with the general net practice on FAQ's, I do not as a rule assign
- credit for solutions. There are many reasons for this:
- 1. The archive is about the answers to the questions, not about assigning
- credit.
- 2. Many people, in providing free answers to the net, do not have the time
- to cite their sources.
- 3. I cut and paste freely from several people's solutions in most cases
- to come up with as complete an answer as possible.
- 4. I use sources other than postings.
- 5. I am neither qualified nor motivated to assign credit.
-
- However, I do whenever possible put bibliographies in archive entries, and
- I see the inclusion of the net addresses of interested parties as a
- logical extension of this practice. In particular, if you wrote a
- program to solve a problem and posted the source code of the program,
- you are presumed to be interested in corresponding with others about
- the problem. So, please let me know the entries you would like to be
- listed in and I will be happy to oblige.
-
- Address corrections or comments to archive-comment@questrel.com.
-
- INDEX
-
- ==> bicycle (analysis) <==
- A boy, a girl and a dog go for a 10 mile walk. The boy and girl can
-
- ==> boy.girl.dog (analysis) <==
- A boy, a girl and a dog are standing together on a long, straight road.
-
- ==> bugs (analysis) <==
- Four bugs are placed at the corners of a square. Each bug walks always
-
- ==> c.infinity (analysis) <==
- What function is zero at zero, strictly positive elsewhere, infinitely
-
- ==> cache (analysis) <==
- Cache and Ferry (How far can a truck go in a desert?)
-
- ==> calculate.pi (analysis) <==
- How can I calculate many digits of pi?
-
- ==> cats.and.rats (analysis) <==
- If 6 cats can kill 6 rats in 6 minutes, how many cats does it take to
-
- ==> dog (analysis) <==
- A body of soldiers form a 50m-by-50m square ABCD on the parade ground.
-
- ==> e.and.pi (analysis) <==
- Without finding their numerical values, which is greater, e^(pi) or (pi)^e?
-
- ==> functional/distributed (analysis) <==
- Find all f: R -> R, f not identically zero, such that
-
- ==> functional/linear (analysis) <==
- Suppose f is non-decreasing with
-
- ==> integral (analysis) <==
- If f is integrable on (0,inf) and differentiable at 0, and a > 0, and:
-
- ==> irrational.stamp (analysis) <==
- You have an ink stamp which is so amazingly precise that, when inked
-
- ==> minimum.time (analysis) <==
- N people can walk or drive in a two-seater to go from city A to city B. What
-
- ==> particle (analysis) <==
- What is the longest time that a particle can take in travelling between two
-
- ==> period (analysis) <==
- What is the least possible integral period of the sum of functions
-
- ==> rubberband (analysis) <==
- A bug walks down a rubber band which is attached to a wall at one end and a car
-
- ==> sequence (analysis) <==
- Show that in the sequence: x, 2x, 3x, .... (n-1)x (x can be any real number)
-
- ==> snow (analysis) <==
- Snow starts falling before noon on a cold December day. At noon a
-
- ==> tower (analysis) <==
- R = N ^ (N ^ (N ^ ...)). What is the maximum N>0 that will yield a finite R?
-
- ==> 7-11 (arithmetic/part1) <==
- A customer at a 7-11 store selected four items to buy, and was told
-
- ==> arithmetic.progression (arithmetic/part1) <==
- Is there an arithmetic progression of 20 or more primes?
-
- ==> clock/day.of.week (arithmetic/part1) <==
- It's restful sitting in Tom's cosy den, talking quietly and sipping
-
- ==> clock/palindromic (arithmetic/part1) <==
- How many times per day does a digital clock display a palindromic number?
-
- ==> clock/reversible (arithmetic/part1) <==
- How many times per day can the hour and minute hands on an analog clock switch
-
- ==> clock/right.angle (arithmetic/part1) <==
- How many times per day do the hour and minute hands of a clock form a
-
- ==> clock/thirds (arithmetic/part1) <==
- Do the 3 hands on a clock ever divide the face of the clock into 3
-
- ==> consecutive.composites (arithmetic/part1) <==
- Are there 10,000 consecutive non-prime numbers?
-
- ==> consecutive.product (arithmetic/part1) <==
- Prove that the product of three or more consecutive positive integers cannot
-
- ==> consecutive.sums (arithmetic/part1) <==
- Find all series of consecutive positive integers whose sum is exactly 10,000.
-
- ==> conway (arithmetic/part1) <==
- Describe the sequence a(1)=a(2)=1, a(n) = a(a(n-1)) + a(n-a(n-1)) for n>2.
-
- ==> digits/6.and.7 (arithmetic/part1) <==
- Does every number which is not divisible by 5 have a multiple whose
-
- ==> digits/all.ones (arithmetic/part1) <==
- Prove that some multiple of any integer ending in 3 contains all 1s.
-
- ==> digits/arabian (arithmetic/part1) <==
- What is the Arabian Nights factorial, the number x such that x! has 1001
-
- ==> digits/circular (arithmetic/part1) <==
- What 6 digit number, with 6 different digits, when multiplied by all integers
-
- ==> digits/divisible (arithmetic/part1) <==
- Find the least number using 0-9 exactly once that is evenly divisible by each
-
- ==> digits/equations/123456789 (arithmetic/part1) <==
- In how many ways can "." be replaced with "+", "-", or "" (concatenate) in
-
- ==> digits/equations/1992 (arithmetic/part1) <==
- 1 = -1+9-9+2. Extend this list to 2 through 100 on the left side of
-
- ==> digits/equations/24 (arithmetic/part1) <==
- Form an expression that evaluates to 24 that contains two 3's, two 7's,
-
- ==> digits/equations/383 (arithmetic/part1) <==
- Make 383 out of 1,2,25,50,75,100 using +,-,*,/.
-
- ==> digits/equations/find (arithmetic/part1) <==
- Write a program for finding expressions built out of given numbers and using
-
- ==> digits/extreme.products (arithmetic/part1) <==
- What are the extremal products of three three-digit numbers using digits 1-9?
-
- ==> digits/labels (arithmetic/part1) <==
- You have an arbitrary number of model kits (which you assemble for
-
- ==> digits/least.significant/factorial (arithmetic/part1) <==
- What is the least significant non-zero digit in the decimal expansion of n!?
-
- ==> digits/least.significant/tower.of.power (arithmetic/part1) <==
- What are the least significant digits of 9^(8^(7^(6^(5^(4^(3^(2^1))))))) ?
-
- ==> digits/most.significant/googol (arithmetic/part1) <==
- What digits does googol! start with?
-
- ==> digits/most.significant/powers (arithmetic/part1) <==
- What is the probability that 2^N begins with the digits 603245?
-
- ==> digits/nine.digits (arithmetic/part1) <==
- Form a number using 0-9 once with its first n digits divisible by n.
-
- ==> digits/palindrome (arithmetic/part1) <==
- Does the series formed by adding a number to its reversal always end in
-
- ==> digits/palintiples (arithmetic/part1) <==
- Find all numbers that are multiples of their reversals.
-
- ==> digits/power.two (arithmetic/part1) <==
- Prove that for any 9-digit number (base 10) there is an integral power
-
- ==> digits/prime/101 (arithmetic/part1) <==
- How many primes are in the sequence 101, 10101, 1010101, ...?
-
- ==> digits/prime/all.prefix (arithmetic/part1) <==
- What is the longest prime whose every proper prefix is a prime?
-
- ==> digits/prime/change.one (arithmetic/part1) <==
- What is the smallest number that cannot be made prime by changing a single
-
- ==> digits/prime/prefix.one (arithmetic/part1) <==
- 2 is prime, but 12, 22, ..., 92 are not. Similarly, 5 is prime
-
- ==> digits/reverse (arithmetic/part1) <==
- Is there an integer that has its digits reversed after dividing it by 2?
-
- ==> digits/rotate (arithmetic/part1) <==
- Find integers where multiplying them by single digits rotates their digits
-
- ==> digits/sesqui (arithmetic/part1) <==
- Find the least number where moving the first digit to the end multiplies by 1.5.
-
- ==> digits/squares/change.leading (arithmetic/part1) <==
- What squares remain squares when their leading digits are incremented?
-
- ==> digits/squares/length.22 (arithmetic/part1) <==
- Is it possible to form two numbers A and B from 22 digits such that
-
- ==> digits/squares/length.9 (arithmetic/part1) <==
- Is it possible to make a number and its square, using the digits from 1
-
- ==> digits/squares/three.digits (arithmetic/part2) <==
- What squares consist entirely of three digits (e.g., 1, 4, and 9)?
-
- ==> digits/squares/twin (arithmetic/part2) <==
- Let a twin be a number formed by writing the same number twice,
-
- ==> digits/sum.of.digits (arithmetic/part2) <==
- Find sod ( sod ( sod (4444 ^ 4444 ) ) ).
-
- ==> digits/zeros/million (arithmetic/part2) <==
- How many zeros occur in the numbers from 1 to 1,000,000?
-
- ==> digits/zeros/trailing (arithmetic/part2) <==
- How many trailing zeros are in the decimal expansion of n!?
-
- ==> magic.squares (arithmetic/part2) <==
- Are there large squares, containing only consecutive integers, all of whose
-
- ==> pell (arithmetic/part2) <==
- Find integer solutions to x^2 - 92y^2 = 1.
-
- ==> subset (arithmetic/part2) <==
- Prove that all sets of n integers contain a subset whose sum is divisible by n.
-
- ==> sum.of.cubes (arithmetic/part2) <==
- Find two fractions whose cubes total 6.
-
- ==> sums.of.powers (arithmetic/part2) <==
- Partition 1,2,3,...,16 into two equal sets, such that the sums of the
-
- ==> tests.for.divisibility/eleven (arithmetic/part2) <==
- What is the test to see if a number is divisible by eleven?
-
- ==> tests.for.divisibility/nine (arithmetic/part2) <==
- What is the test to see if a number is divisible by nine?
-
- ==> tests.for.divisibility/seven (arithmetic/part2) <==
- What is the test to see if a number is divisible by seven?
-
- ==> tests.for.divisibility/three (arithmetic/part2) <==
- What is the test to see if a number is divisible by three?
-
- ==> alphabet.blocks (combinatorics) <==
- What is the minimum number of dice painted with one letter on all six sides
-
- ==> coinage/combinations (combinatorics) <==
- Assuming you have enough coins of 1, 5, 10, 25 and 50 cents, how many
-
- ==> coinage/dimes (combinatorics) <==
- "Dad wants one-cent, two-cent, three-cent, five-cent, and ten-cent
-
- ==> coinage/impossible (combinatorics) <==
- What is the smallest number of coins that you can't make a dollar with?
-
- ==> color (combinatorics) <==
- An urn contains n balls of different colors. Randomly select a pair, repaint
-
- ==> full (combinatorics) <==
- Consider a string that contains all substrings of length n. For example,
-
- ==> gossip (combinatorics) <==
- n people each know a different piece of gossip. They can telephone each other
-
- ==> grid.dissection (combinatorics) <==
- How many (possibly overlapping) squares are in an mxn grid? Assume that all
-
- ==> permutation (combinatorics) <==
- Compute the nth permutation of k numbers (or objects).
-
- ==> subsets (combinatorics) <==
- Out of the set of integers 1,...,100 you are given ten different
-
- ==> transitions (combinatorics) <==
- How many n-bit binary strings (0/1) have exactly k transitions
-
- ==> contests/games.magazine (competition/part1) <==
- What are the best answers to various contests run by _Games_ magazine?
-
- ==> contests/national.puzzle/npc.1993 (competition/part1) <==
- What are the solutions to the Games magazine 1993 National Puzzle Contest?
-
- ==> games/bridge (competition/part1) <==
- Are there any programs for solving double-dummy Bridge?
-
- ==> games/chess/knight.control (competition/part1) <==
- How many knights does it take to attack or control the board?
-
- ==> games/chess/knight.most (competition/part1) <==
- What is the maximum number of knights that can be put on n x n chessboard
-
- ==> games/chess/knight.tour (competition/part1) <==
- For what size boards are knight tours possible?
-
- ==> games/chess/mutual.stalemate (competition/part1) <==
- What's the minimal number of pieces in a legal mutual stalemate?
-
- ==> games/chess/queen.control (competition/part1) <==
- How many queens does it take to attack or control the board?
-
- ==> games/chess/queen.most (competition/part1) <==
- How many non-mutually-attacking queens can be placed on various sized boards?
-
- ==> games/chess/queens (competition/part1) <==
- How many ways can eight queens be placed so that they control the board?
-
- ==> games/chess/rook.paths (competition/part1) <==
- How many non-overlapping paths can a rook take from one corner to the opposite
-
- ==> games/chess/size.of.game.tree (competition/part1) <==
- How many different positions are there in the game tree of chess?
-
- ==> games/cigarettes (competition/part1) <==
- The game of cigarettes is played as follows:
-
- ==> games/connect.four (competition/part1) <==
- Is there a winning strategy for Connect Four?
-
- ==> games/craps (competition/part1) <==
- What are the odds in craps?
-
- ==> games/crosswords (competition/part1) <==
- Are there programs to make crosswords? What are the rules for cluing cryptic
-
- ==> games/cube (competition/part2) <==
- What are some games involving cubes?
-
- ==> games/go-moku (competition/part2) <==
- For a game of k in a row on an n x n board, for what values of k and n is
-
- ==> games/hi-q (competition/part2) <==
- What is the quickest solution of the game Hi-Q (also called Solitaire)?
-
- ==> games/jeopardy (competition/part2) <==
- What are the highest, lowest, and most different scores contestants
-
- ==> games/nim (competition/part2) <==
- Place 10 piles of 10 $1 bills in a row. A valid move is to reduce
-
- ==> games/online/online.scrabble (competition/part2) <==
- How can I play Scrabble online on the Internet?
-
- ==> games/online/unlimited.adventures (competition/part2) <==
- Where can I find information about unlimited adventures?
-
- ==> games/othello (competition/part2) <==
- How good are computers at Othello?
-
- ==> games/pc/best (competition/part2) <==
- What are the best PC games?
-
- ==> games/pc/reviews (competition/part2) <==
- Are reviews of PC games available online?
-
- ==> games/pc/solutions (competition/part2) <==
- What are the solutions to various popular PC games?
-
- ==> games/poker.face.up (competition/part2) <==
- In Face-Up Poker, two players each select five cards from a face-up deck,
-
- ==> games/risk (competition/part2) <==
- What are the odds when tossing dice in Risk?
-
- ==> games/rubiks/rubiks.clock (competition/part2) <==
- How do you quickly solve Rubik's clock?
-
- ==> games/rubiks/rubiks.cube (competition/part3) <==
- What is known about bounds on solving Rubik's cube?
-
- ==> games/rubiks/rubiks.magic (competition/part3) <==
- How do you solve Rubik's Magic?
-
- ==> games/scrabble (competition/part3) <==
- What are some exceptional Scrabble Brand Crossword Game (TM) games?
-
- ==> games/set (competition/part3) <==
- What is the size of the largest collection of cards from which NO "set"
-
- ==> games/soma (competition/part3) <==
- What is the solution to Soma Cubes?
-
- ==> games/square-1 (competition/part3) <==
- Does anyone have any hints on how to solve the Square-1 puzzle?
-
- ==> games/think.and.jump (competition/part3) <==
- THINK & JUMP: FIRST THINK, THEN JUMP UNTIL YOU
-
- ==> games/tictactoe (competition/part3) <==
- In random tic-tac-toe, what is the probability that the first mover wins?
-
- ==> tests/analogies/long (competition/part3) <==
- 1. Host : Guest :: Cynophobia : ?
-
- ==> tests/analogies/pomfrit (competition/part3) <==
- 1. NATURAL: ARTIFICIAL :: ANKYLOSIS: ?
-
- ==> tests/analogies/quest (competition/part3) <==
- 1. Mother: Maternal :: Stepmother: ?
-
- ==> tests/math/putnam/putnam.1967 (competition/part3) <==
-
-
- ==> tests/math/putnam/putnam.1987 (competition/part4) <==
- WILLIAM LOWELL PUTNAM MATHEMATICAL COMPETITION
-
- ==> tests/math/putnam/putnam.1988 (competition/part4) <==
- Problem A-1: Let R be the region consisting of the points (x,y) of the
-
- ==> tests/math/putnam/putnam.1990 (competition/part4) <==
- Problem A-1
-
- ==> tests/math/putnam/putnam.1992 (competition/part5) <==
- Problem A1
-
- ==> Beale (cryptology) <==
- What are the Beale ciphers?
-
- ==> Feynman (cryptology) <==
- What are the Feynman ciphers?
-
- ==> Voynich (cryptology) <==
- What are the Voynich ciphers?
-
- ==> swiss.colony (cryptology) <==
- What are the 1987 Swiss Colony ciphers?
-
- ==> vcrplus (cryptology) <==
- What is the code used by VCR+?
-
- ==> allais (decision) <==
- The Allais Paradox involves the choice between two alternatives:
-
- ==> division (decision) <==
- N-Person Fair Division
-
- ==> dowry (decision) <==
- Sultan's Dowry
-
- ==> envelope (decision) <==
- Someone has prepared two envelopes containing money. One contains twice as
-
- ==> exchange (decision) <==
- At one time, the Canadian and US dollars were discounted by 10 cents on
-
- ==> high.or.low (decision) <==
- I pick two numbers, randomly, and tell you one of them. You are supposed
-
- ==> monty.hall (decision) <==
- You are a participant on "Let's Make a Deal." Monty Hall shows you
-
- ==> newcomb (decision) <==
- Newcomb's Problem
-
- ==> prisoners (decision) <==
- Three prisoners on death row are told that one of them has been chosen
-
- ==> red (decision) <==
- I show you a shuffled deck of standard playing cards, one card at a
-
- ==> rotating.table (decision) <==
- Four glasses are placed upside down in the four corners of a square
-
- ==> stpetersburg (decision) <==
- What should you be willing to pay to play a game in which the payoff is
-
- ==> truel (decision) <==
- A, B, and C are to fight a three-cornered pistol duel. All know that
-
- ==> K3,3 (geometry/part1) <==
- Can three houses be connected to three utilities without the pipes crossing?
-
- ==> bear (geometry/part1) <==
- If a hunter goes out his front door, goes 50 miles south, then goes 50
-
- ==> bisector (geometry/part1) <==
- Prove if two angle bisectors of a triangle are equal, then the triangle is
-
- ==> calendar (geometry/part1) <==
- Build a calendar from two sets of cubes. On the first set, spell the
-
- ==> circles.and.triangles (geometry/part1) <==
- Find the radius of the inscribed and circumscribed circles for a triangle.
-
- ==> coloring/cheese.cube (geometry/part1) <==
- A cube of cheese is divided into 27 subcubes. A mouse starts at one
-
- ==> coloring/triominoes (geometry/part1) <==
- There is a chess board (of course with 64 squares). You are given 21
-
- ==> construction/4.triangles.6.lines (geometry/part1) <==
- Can you construct 4 equilateral triangles with 6 toothpicks?
-
- ==> construction/5.lines.with.4.points (geometry/part1) <==
- Arrange 10 points so that they form 5 rows of 4 each.
-
- ==> construction/square.with.compass (geometry/part1) <==
- Construct a square with only a compass and a straight edge.
-
- ==> corner (geometry/part1) <==
- A hallway of width A turns through 90 degrees into a hallway of width
-
- ==> cover.earth (geometry/part1) <==
- A thin membrane covers the surface of the (spherical) earth. One
-
- ==> cycle.polynomial (geometry/part1) <==
- What are the cycle polynomials for the Platonic solids?
-
- ==> dissections/disk (geometry/part1) <==
- Can a disk be cut into similar pieces without point symmetry about the
-
- ==> dissections/hexagon (geometry/part1) <==
- Divide the hexagon into:
-
- ==> dissections/largest.circle (geometry/part1) <==
- What is the largest circle that can be assembled from two semicircles cut from
-
- ==> dissections/square.70 (geometry/part1) <==
- Since 1^2 + 2^2 + 3^2 + ... + 24^2 = 70^2, can a 70x70 square be dissected into
-
- ==> dissections/square.five (geometry/part1) <==
- Can you dissect a square into 5 parts of equal area with just a straight edge?
-
- ==> dissections/tesseract (geometry/part1) <==
- If you suspend a cube by one corner and slice it in half with a
-
- ==> duck.and.fox (geometry/part1) <==
- A duck is swimming about in a circular pond. A ravenous fox (who cannot
-
- ==> earth.band (geometry/part1) <==
- How much will a band around the equator rise above the surface if it is
-
- ==> fence (geometry/part1) <==
- A farmer wishes to enclose the maximum possible area with 100 meters of fence.
-
- ==> ham.sandwich (geometry/part1) <==
- Consider a ham sandwich, consisting of two pieces of bread and one of
-
- ==> hike (geometry/part1) <==
- You are hiking in a half-planar woods, exactly 1 mile from the edge,
-
- ==> hole.in.sphere (geometry/part1) <==
- Old Boniface he took his cheer,
-
- ==> hypercube (geometry/part1) <==
- How many vertices, edges, faces, etc. does a hypercube have?
-
- ==> kissing.number (geometry/part1) <==
- How many n-dimensional unit spheres can be packed around one unit sphere?
-
- ==> konigsberg (geometry/part1) <==
- Can you draw a line through each edge on the diagram below without crossing
-
- ==> ladders (geometry/part1) <==
- Two ladders form a rough X in an alley. The ladders are 11 and 13 meters
-
- ==> lattice/area (geometry/part1) <==
- Prove that the area of a triangle formed by three lattice points is integer/2.
-
- ==> lattice/equilateral (geometry/part1) <==
- Can an equlateral triangle have vertices at integer lattice points?
-
- ==> manhole.cover (geometry/part1) <==
- Why is a manhole cover round?
-
- ==> pentomino (geometry/part1) <==
- Arrange pentominos in 3x20, 4x15, 5x12, 6x10, 2x3x10, 2x5x6 and 3x4x5 forms.
-
- ==> points.in.sphere (geometry/part1) <==
- What is the expected distance between two random points inside a sphere?
-
- ==> points.on.sphere (geometry/part1) <==
- What are the odds that n random points on a sphere lie in the same hemisphere?
-
- ==> revolutions (geometry/part1) <==
- A circle with radius 1 rolls without slipping once around a circle with radius
-
- ==> rotation (geometry/part1) <==
- What is the smallest rotation that returns an object to its original state?
-
- ==> shephard.piano (geometry/part1) <==
- What's the maximum area shape that will fit around a right-angle corner?
-
- ==> smuggler (geometry/part1) <==
- Somewhere on the high sees smuggler S is attempting, without much
-
- ==> spiral (geometry/part1) <==
- How far must one travel to reach the North Pole if one starts from the
-
- ==> table.in.corner (geometry/part1) <==
- Put a round table into a (perpendicular) corner so that the table top
-
- ==> tetrahedron (geometry/part1) <==
- Suppose you have a sphere of radius R and you have four planes that are
-
- ==> tiling/count.1x2 (geometry/part1) <==
- Count the ways to tile an MxN rectangle with 1x2 dominos.
-
- ==> tiling/rational.sides (geometry/part1) <==
- A rectangular region R is divided into rectangular areas. Show that if
-
- ==> tiling/rectangles.with.squares (geometry/part2) <==
- Given two sorts of squares, (axa) and (bxb), what rectangles can be tiled?
-
- ==> tiling/scaling (geometry/part2) <==
- A given rectangle can be entirely covered (i.e. concealed) by an
-
- ==> tiling/seven.cubes (geometry/part2) <==
- Consider 7 cubes of equal size arranged as follows. Place 5 cubes so
-
- ==> topology/fixed.point (geometry/part2) <==
- A man hikes up a mountain, and starts hiking at 2:00 in the afternoon
-
- ==> touching.blocks (geometry/part2) <==
- Can six 1x2x4 blocks be arranged so that each block touches n others, for all n?
-
- ==> trigonometry/euclidean.numbers (geometry/part2) <==
- For what numbers x is sin(x) expressible using only integers, +, -, *, / and
-
- ==> trigonometry/inequality (geometry/part2) <==
- Show that (sin x)^(sin x) < (cos x)^(cos x) when 0 < x < pi/4.
-
- ==> group.01 (group) <==
- AEFHIKLMNTVWXYZ BCDGJOPQRSU
-
- ==> group.01a (group) <==
- 147 0235689
-
- ==> group.02 (group) <==
- ABEHIKMNOTXZ CDFGJLPQRSUVWY
-
- ==> group.03 (group) <==
- BEJQXYZ DFGHLPRU KSTV CO AIW MN
-
- ==> group.04 (group) <==
- BDO P ACGIJLMNQRSUVWZ EFTY HKX
-
- ==> group.05 (group) <==
- CEFGHIJKLMNSTUVWXYZ ADOPQR B
-
- ==> group.06 (group) <==
- BCEGKMQSW DFHIJLNOPRTUVXYZ
-
- ==> group.07 (group) <==
- CDEFLOPTZ ABGHIJKMNQRSUVWXY
-
- ==> group.08 (group) <==
- COS ABDEFGHIJKLMNPQRTUVWXYZ
-
- ==> group.09 (group) <==
- CDILMVX ABEFGHJKNOPQRSTUWYZ
-
- ==> group.10 (group) <==
- AHIMOTUVWXY BCDEFGJKLNPQRSZ
-
- ==> group.11 (group) <==
- BCDIJLMNOPQRSUVWZ AEFGHKTXY
-
- ==> group.12 (group) <==
- COPSUVWXZ ABDEFGHIJKLMNQRTY
-
- ==> group.13 (group) <==
- BCDEHIKOX AFGJLMNPQRSTUVWYZ
-
- ==> group.14 (group) <==
- EHIS MOT ABCDFGJKLNPQRUVWXYZ
-
- ==> group.15 (group) <==
- HIOX ABCDEFGJKLMNPQRSTUVWYZ
-
- ==> group.16 (group) <==
- IJ ABCDEFGHKLMNOPQRSTUVWXYZ
-
- ==> group.17 (group) <==
- J BDFHIKLT GPQY ACEMNORSUVWXZ
-
- ==> handshake (induction) <==
- A married couple organizes a party. They only invite other married
-
- ==> hanoi (induction) <==
- Is there an algorithm for solving the Hanoi tower puzzle for any number
-
- ==> n-sphere (induction) <==
- With what odds do three random points on an n-sphere form an acute triangle?
-
- ==> paradox (induction) <==
- Is there a non-trivial property that holds for the first 10,000 positive
-
- ==> party (induction) <==
- You're at a party. Any two (different) people at the party have exactly one
-
- ==> roll (induction) <==
- An ordinary die is thrown until the running total of the throws first
-
- ==> takeover (induction) <==
- After graduating from college, you have taken an important managing position
-
- ==> close.antonyms (language/part1) <==
- What words are similar to their antonyms in other langauges?
-
- ==> dutch/dutch.record (language/part1) <==
- What are some Dutch words with unusual properties?
-
- ==> english/equations (language/part1) <==
- 1 = E. on a C.
-
- ==> english/etymology/acronym (language/part1) <==
- What acronyms have become common words or are otherwise interesting?
-
- ==> english/etymology/fossil (language/part1) <==
- What are some examples of idioms that include obsolete words?
-
- ==> english/etymology/portmanteau (language/part1) <==
- What are some words formed by combining together parts of other words?
-
- ==> english/frequency (language/part1) <==
- In the English language, what are the most frequently appearing:
-
- ==> english/idioms (language/part1) <==
- List some idioms that say the opposite of what they mean.
-
- ==> english/less.ness (language/part1) <==
- Find a word that forms two other words, unrelated in meaning, when "less"
-
- ==> english/letter.rebus (language/part1) <==
- Define the letters of the alphabet using self-referential common phrases (e.g.,
-
- ==> english/malaprop (language/part1) <==
- List some phrases with the same meaning that differ by one sound.
-
- ==> english/piglatin (language/part1) <==
- What words in pig latin also are words?
-
- ==> english/pleonasm (language/part1) <==
- What are some redundant terms that occur frequently (like "ABM missile")?
-
- ==> english/plurals/collision (language/part1) <==
- Two words, spelled and pronounced differently, have plurals spelled
-
- ==> english/plurals/doubtful.number (language/part1) <==
- A little word of doubtful number,
-
- ==> english/plurals/drop.terminal (language/part1) <==
- What words have their plurals formed by dropping the final letter?
-
- ==> english/plurals/endings (language/part1) <==
- List a plural ending with each letter of the alphabet.
-
- ==> english/plurals/man (language/part1) <==
- Words ending with "man" make their plurals by adding "s".
-
- ==> english/plurals/switch.first (language/part1) <==
- What plural is formed by switching the first two letters?
-
- ==> english/potable.color (language/part1) <==
- Find words that are both beverages and colors.
-
- ==> english/pronunciation/autonym (language/part1) <==
- What is the longest word whose phonetic and normal spellings are the same?
-
- ==> english/pronunciation/homograph/different.pronunciation (language/part1) <==
- What sequence of letters has the most different pronunciations?
-
- ==> english/pronunciation/homograph/homographs (language/part1) <==
- List some homographs (words spelled the same but pronounced differently)
-
- ==> english/pronunciation/homophone/homophones.alphabet (language/part1) <==
- Homophones can be confusing when used to exemplify a letter. For example,
-
- ==> english/pronunciation/homophone/homophones.letter (language/part1) <==
- For each letter, list homophones that differ by that letter.
-
- ==> english/pronunciation/homophone/homophones.most (language/part1) <==
- What words have four or more spellings that sound alike?
-
- ==> english/pronunciation/homophone/trivial (language/part2) <==
- Consider the free non-abelian group on the twenty-six letters of the
-
- ==> english/pronunciation/oronym (language/part2) <==
- List some oronyms (phrases or sentences that can be read in two ways
-
- ==> english/pronunciation/phonetic.letters (language/part2) <==
- What does "FUNEX" mean?
-
- ==> english/pronunciation/rhyme (language/part2) <==
- What English words are hard to rhyme?
-
- ==> english/pronunciation/silent.letter (language/part2) <==
- For each letter, what word contains that letter silent?
-
- ==> english/pronunciation/silent.most (language/part2) <==
- What word has the most silent letters in a row?
-
- ==> english/pronunciation/syllable (language/part2) <==
- What words have an exceptional number of letters per syllable?
-
- ==> english/pronunciation/telegrams (language/part2) <==
- Since telegrams cost by the word, phonetically similar messages can be cheaper.
-
- ==> english/puns (language/part2) <==
- Where can I find a collection of puns?
-
- ==> english/rare.trigraphs (language/part2) <==
- What trigraphs (three-letter combinations) occur in only one word?
-
- ==> english/self.ref/self.ref.letters (language/part2) <==
- Construct a true sentence of the form: "This sentence contains _ a's, _ b's,
-
- ==> english/self.ref/self.ref.numbers (language/part2) <==
- What true sentence has the form: "There are _ 0's, _ 1's, _ 2's, ...,
-
- ==> english/self.ref/self.ref.words (language/part2) <==
- What sentence describes its own word, syllable and letter count?
-
- ==> english/sentences/behead (language/part2) <==
- Is there a sentence that remains a sentence when all its words are beheaded?
-
- ==> english/sentences/charades (language/part2) <==
- A ....... surgeon was ....... to operate because he had .......
-
- ==> english/sentences/emphasis (language/part2) <==
- List some sentences that change meaning when the emphasis is moved.
-
- ==> english/sentences/pangram (language/part2) <==
- A "pangram" is a sentence containing all 26 letters.
-
- ==> english/sentences/repeated.words (language/part2) <==
- What is a sentence with the same word several times repeated? Do not use
-
- ==> english/sentences/sentence (language/part2) <==
- Find a sentence with words beginning with the letters of the alphabet, in order.
-
- ==> english/sentences/snowball (language/part2) <==
- Construct the longest coherent sentence you can such that the nth word
-
- ==> english/sentences/weird (language/part2) <==
- Make a sentence containing only words that violate the "i before e" rule.
-
- ==> english/sentences/word.boundaries (language/part2) <==
- List some sentences that can be radically altered by changing word boundaries
-
- ==> english/spelling/gry (language/part2) <==
- Find three completely different words ending in "gry."
-
- ==> english/spelling/j.ending (language/part2) <==
- What words and names end in j?
-
- ==> english/spelling/lipograms (language/part2) <==
- What books have been written without specific letters, vowels, etc.?
-
- ==> english/spelling/longest (language/part2) <==
- What is the longest word in the English language?
-
- ==> english/spelling/most (language/part2) <==
- What word has the most variant spellings?
-
- ==> english/spelling/near.palindrome (language/part2) <==
- What are some long near palindromes, i.e., words that except for one
-
- ==> english/spelling/operations.on.words/deletion (language/part2) <==
- What exceptional words turn into other words by deletion of letters?
-
- ==> english/spelling/operations.on.words/insertion.and.deletion (language/part2) <==
- What exceptional words turn into other words by both insertion and
-
- ==> english/spelling/operations.on.words/insertion (language/part2) <==
- What exceptional words turn into other words by insertion of letters?
-
- ==> english/spelling/operations.on.words/movement (language/part2) <==
- What exceptional words turn into other words by movement of letters?
-
- ==> english/spelling/operations.on.words/substitution (language/part2) <==
- What exceptional words turn into other words by substitution of letters?
-
- ==> english/spelling/operations.on.words/transposition (language/part3) <==
- What exceptional words turn into other words by transposition of letters?
-
- ==> english/spelling/operations.on.words/words.within.words (language/part3) <==
- What exceptional words contain other words?
-
- ==> english/spelling/palindromes (language/part3) <==
- What are some long palindromes?
-
- ==> english/spelling/sets.of.words/ladder (language/part3) <==
- Find the shortest word ladders stretching between the following pairs:
-
- ==> english/spelling/sets.of.words/nots.and.crosses (language/part3) <==
- What is the most number of letters that can be fit into a three by three grid
-
- ==> english/spelling/sets.of.words/perfect.ladder (language/part3) <==
- A "perfect" ladder comprises five-letter words where every letter is
-
- ==> english/spelling/sets.of.words/squares (language/part3) <==
- What are some exceptional word squares (square crosswords with no blanks)?
-
- ==> english/spelling/sets.of.words/variogram (language/part3) <==
- What is the largest known variogram (word square where repeated letters count
-
- ==> english/spelling/sets.of.words/word.torture (language/part3) <==
- What is the longest word all of whose contiguous subsequences are words?
-
- ==> english/spelling/single.words (language/part3) <==
- What words have exceptional lengths, patterns, etc.?
-
- ==> english/spoonerisms (language/part3) <==
- List some exceptional spoonerisms.
-
- ==> english/synonyms/ambiguous (language/part3) <==
- What word in the English language is the most ambiguous?
-
- ==> english/synonyms/antonym (language/part3) <==
- What words, when a single letter is added, reverse their meanings?
-
- ==> english/synonyms/contradictory.proverbs (language/part3) <==
- What are some proverbs that contradict one another?
-
- ==> english/synonyms/contranym (language/part3) <==
- What words are their own antonym?
-
- ==> english/synonyms/double.synonyms (language/part3) <==
- What words have two different synonymous meanings?
-
- ==> finnish/finnish.plural (language/part3) <==
- What Finnish word is the anagram of its plural?
-
- ==> finnish/finnish.record (language/part4) <==
- What are some Finnish words with unusual properties?
-
- ==> french/french.palindromes (language/part4) <==
- List some French palindromes.
-
- ==> french/french.record (language/part4) <==
- What are some French words with unusual properties?
-
- ==> german/german.palindromes (language/part4) <==
- List some German palindromes.
-
- ==> german/german.record (language/part4) <==
- What are some German words with unusual properties?
-
- ==> italian/italian.record (language/part5) <==
- What are some Italian words with unusual properties?
-
- ==> multi.palindromes (language/part5) <==
- List some multi-lingual palindromes.
-
- ==> norwegian/norwegian.record (language/part5) <==
- What are some Norwegian words with unusual properties?
-
- ==> repeated.word (language/part5) <==
- In any language, construct a sentence by repeating one word four times.
-
- ==> swedish/swedish.record (language/part5) <==
- What are some Swedish words with unusual properties?
-
- ==> synonymous.reversals (language/part5) <==
- What words are synonymous with their reversals in other langauges?
-
- ==> vowels.repeated (language/part5) <==
- In any language, what word contains the same vowel repeated four times in a row?
-
- ==> 29 (logic/part1) <==
- Three people check into a hotel. They pay $30 to the manager and go
-
- ==> ages (logic/part1) <==
- 1) Ten years from now Tim will be twice as old as Jane was when Mary was
-
- ==> attribute (logic/part1) <==
- All the items in the first list share a particular attribute. The second
-
- ==> bookworm (logic/part1) <==
- A bookworm eats from the first page of an encyclopedia to the last
-
- ==> boxes (logic/part1) <==
- Which Box Contains the Gold?
-
- ==> camel (logic/part1) <==
- An Arab sheikh tells his two sons to race their camels to a distant
-
- ==> centrifuge (logic/part1) <==
- You are a biochemist, working with a 12-slot centrifuge. This is a gadget
-
- ==> chain (logic/part1) <==
- What is the least number of links you can cut in a chain of 21 links to be able
-
- ==> children (logic/part1) <==
- A man walks into a bar, orders a drink, and starts chatting with the
-
- ==> condoms (logic/part1) <==
- How can a man have mutually safe sex with three women with only two condoms?
-
- ==> dell (logic/part1) <==
- How can I solve logic puzzles (e.g., as published by Dell) automatically?
-
- ==> elimination (logic/part1) <==
- 97 baseball teams participate in an annual state tournament.
-
- ==> flip (logic/part1) <==
- How can a toss be called over the phone (without requiring trust)?
-
- ==> flowers (logic/part1) <==
- How many flowers do I have if all of them are roses except two, all of
-
- ==> friends (logic/part1) <==
- Any group of 6 or more contains either 3 mutual friends or 3 mutual strangers.
-
- ==> hofstadter (logic/part1) <==
- In first-order logic, find a predicate P(x) which means "x is a power of 10."
-
- ==> hundred (logic/part1) <==
- A sheet of paper has statements numbered from 1 to 100. Statement n says
-
- ==> inverter (logic/part1) <==
- Can a digital logic circuit with two inverters invert N independent inputs?
-
- ==> josephine (logic/part1) <==
- The recent expedition to the lost city of Atlantis discovered scrolls
-
- ==> locks.and.boxes (logic/part1) <==
- You want to send a valuable object to a friend. You have a box which
-
- ==> min.max (logic/part1) <==
- In a rectangular array of people, which will be taller, the tallest of the
-
- ==> mixing (logic/part1) <==
- Start with a half cup of tea and a half cup of coffee. Take one tablespoon
-
- ==> monty.52 (logic/part1) <==
- Monty and Waldo play a game with N closed boxes. Monty hides a
-
- ==> number (logic/part1) <==
- Mr. S. and Mr. P. are both perfect logicians, being able to correctly deduce
-
- ==> riddle (logic/part2) <==
- Who makes it, has no need of it. Who buys it, has no use for it. Who
-
- ==> river.crossing (logic/part2) <==
- Three humans, one big monkey and two small monkeys are to cross a river:
-
- ==> ropes (logic/part2) <==
- Two fifty foot ropes are suspended from a forty foot ceiling, about
-
- ==> same.street (logic/part2) <==
- Sally and Sue have a strong desire to date Sam. They all live on the
-
- ==> self.ref (logic/part2) <==
- Find a number ABCDEFGHIJ such that A is the count of how many 0's are in the
-
- ==> situation.puzzles (logic/part3) <==
- Jed's List of Situation Puzzles
-
- ==> smullyan/black.hat (logic/part4) <==
- Three logicians, A, B, and C, are wearing hats, which they know are either
-
- ==> smullyan/fork.three.men (logic/part4) <==
- Three men stand at a fork in the road. One fork leads to Someplaceorother;
-
- ==> smullyan/fork.two.men (logic/part4) <==
- Two men stand at a fork in the road. One fork leads to Someplaceorother; the
-
- ==> smullyan/integers (logic/part4) <==
- Two logicians place cards on their foreheads so that what is written on the
-
- ==> smullyan/painted.heads (logic/part4) <==
- While three logicians were sleeping under a tree, a malicious child painted
-
- ==> smullyan/priest (logic/part5) <==
- In a small town there are N married couples in which one of the pair
-
- ==> smullyan/stamps (logic/part5) <==
- The moderator takes a set of 8 stamps, 4 red and 4 green, known to the
-
- ==> supertasks (logic/part5) <==
- You have an empty urn, and an infinite number of labeled balls. Each
-
- ==> timezone (logic/part5) <==
- Two people are talking long distance on the phone; one is in an East-
-
- ==> unexpected (logic/part5) <==
- Swedish civil defense authorities announced that a civil defense drill would
-
- ==> verger (logic/part5) <==
- A very bright and sunny Day
-
- ==> weighing/balance (logic/part5) <==
- You are given 12 identical-looking coins, one of which is counterfeit
-
- ==> weighing/box (logic/part5) <==
- You have ten boxes; each contains nine balls. The balls in one box
-
- ==> weighing/find.median (logic/part5) <==
- What is the least number of pairwise comparisons needed to find the median of
-
- ==> weighing/gummy.bears (logic/part5) <==
- Real gummy drop bears have a mass of 10 grams, while imitation gummy
-
- ==> weighing/optimal.weights (logic/part5) <==
- What is the smallest set of weights that allow you to weigh on a
-
- ==> weighing/weighings (logic/part5) <==
- Some of the supervisors of Scandalvania's n mints are producing bogus coins.
-
- ==> zoo (logic/part5) <==
- I took some nephews and nieces to the Zoo, and we halted at a cage marked
-
- ==> balloon (physics) <==
- A helium-filled balloon is tied to the floor of a car that makes a
-
- ==> brick (physics) <==
- What is the maximum overhang you can create with an infinite supply of bricks?
-
- ==> bubbles (physics) <==
- In a universe with the same physical laws, but which is mostly water
-
- ==> cannonball (physics) <==
- A person in a boat drops a cannonball overboard; does the water level change?
-
- ==> magnets (physics) <==
- You have two bars of iron. One is magnetized along its length, the
-
- ==> milk.and.coffee (physics) <==
- You are just served a hot cup of coffee and want it to be as hot as
-
- ==> mirror (physics) <==
- Why does a mirror appear to invert the left-right directions, but not up-down?
-
- ==> monkey (physics) <==
- Hanging over a pulley there is a rope, with a weight at one end.
-
- ==> pole.in.barn (physics) <==
- Accelerate a pole of length l to a constant speed of 90% of the speed of
-
- ==> resistors (physics) <==
- What is the resistance between various pairs of vertices on a lattice
-
- ==> sail (physics) <==
- A sailor is in a sailboat on a river. The current is 3 knots with respect
-
- ==> shoot.sun (physics) <==
- If you are standing at the equator at sunrise, where must you point a laser
-
- ==> skid (physics) <==
- What is the fastest way to make a 90 degree turn on a slippery road?
-
- ==> spheres (physics) <==
- Two spheres are the same size and weight, but one is hollow. They are
-
- ==> wind (physics) <==
- Is a round-trip by airplane longer or shorter if there is wind blowing?
-
- ==> pickover.01 (pickover/part1) <==
- Title: Cliff Puzzle 1: Can you beat the numbers game?
-
- ==> pickover.02 (pickover/part1) <==
- Title: Cliff Puzzle 2: Grid of the Gods
-
- ==> pickover.03 (pickover/part1) <==
- Title: Cliff Puzzle 3: Too many 3's
-
- ==> pickover.04 (pickover/part1) <==
- Title: Cliff Puzzle 4: Time in a Bottle
-
- ==> pickover.05 (pickover/part1) <==
- Title: Cliff Puzzle 5: Mystery Sequence
-
- ==> pickover.06 (pickover/part1) <==
- Title: Cliff Puzzle 6: Star Chambers
-
- ==> pickover.07 (pickover/part2) <==
- Title: Cliff Puzzle 7: 3x3 Recursion
-
- ==> pickover.08 (pickover/part2) <==
- Title: Cliff Puzzle 8: Squares and Squares and Squares ....
-
- ==> pickover.09 (pickover/part2) <==
- Title: Cliff Puzzle 9: 3-Atoms and Growth
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- ==> pickover.10 (pickover/part2) <==
- Title: Cliff Puzzle 10: The Ark Series
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- ==> pickover.11 (pickover/part2) <==
- Title: Cliff Puzzle 11: The Leviathan Number
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- ==> pickover.12 (pickover/part3) <==
- Title: Cliff Puzzle 12: Slides in Hell
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- ==> pickover.13 (pickover/part3) <==
- Title: Cliff Puzzle 13: Ladders to Heaven
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- ==> pickover.14 (pickover/part3) <==
- Title: Cliff Puzzle 14: Geography Genuflection
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- ==> pickover.15 (pickover/part3) <==
- Title: Cliff Puzzle 15: Cherries in Wine Glasses
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- ==> pickover.16 (pickover/part3) <==
- Title: Cliff Puzzle 16: Undulating Squares
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- ==> pickover.17 (pickover/part3) <==
- Title: Cliff Puzzle 17: Weird Recursive Sequence
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- ==> pickover.18 (pickover/part3) <==
- Title: Cliff Puzzle 18: Difficult Nested Roots
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- ==> amoeba (probability) <==
- A jar begins with one amoeba. Every minute, every amoeba
-
- ==> apriori (probability) <==
- An urn contains one hundred white and black balls. You sample one hundred
-
- ==> bayes (probability) <==
- One urn contains black marbles, and the other contains white or black
-
- ==> birthday/line (probability) <==
- At a movie theater, the manager announces that they will give a free ticket
-
- ==> birthday/same.day (probability) <==
- How many people must be at a party before you have even odds or better
-
- ==> cab (probability) <==
- A cab was involved in a hit and run accident at night. Two cab companies,
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- ==> coupon (probability) <==
- There is a free gift in my breakfast cereal. The manufacturers say that
-
- ==> darts (probability) <==
- Peter throws two darts at a dartboard, aiming for the center. The
-
- ==> derangement (probability) <==
- 12 men leave their hats with the hat check. If the hats are randomly
-
- ==> family (probability) <==
- Suppose that it is equally likely for a pregnancy to deliver
-
- ==> flips/once.in.run (probability) <==
- What are the odds that a run of one H or T (i.e., THT or HTH) will occur
-
- ==> flips/twice.in.run (probability) <==
- What is the probability in n flips of a fair coin that there will be two
-
- ==> flips/unfair (probability) <==
- Generate even odds from an unfair coin. For example, if you
-
- ==> flips/waiting.time (probability) <==
- Compute the expected waiting time for a sequence of coin flips, or the
-
- ==> flush (probability) <==
- Which set contains proportionately more flushes than the set of all
-
- ==> hospital (probability) <==
- A town has two hospitals, one big and one small. Every day the big
-
- ==> icos (probability) <==
- The "house" rolls two 20-sided dice and the "player" rolls one
-
- ==> intervals (probability) <==
- Given two random points x and y on the interval 0..1, what is the average
-
- ==> killers.and.pacifists (probability) <==
- You enter a town that has K killers and P pacifists. When a
-
- ==> leading.digit (probability) <==
- What is the probability that the ratio of two random reals starts with a 1?
-
- ==> lights (probability) <==
- Waldo and Basil are exactly m blocks west and n blocks north from
-
- ==> lottery (probability) <==
- There n tickets in the lottery, k winners and m allowing you to pick another
-
- ==> oldest.girl (probability) <==
- You meet a stranger on the street, and ask how many children he has. He
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- ==> particle.in.box (probability) <==
- A particle is bouncing randomly in a two-dimensional box. How far does it
-
- ==> pi (probability) <==
- Are the digits of pi random (i.e., can you make money betting on them)?
-
- ==> random.walk (probability) <==
- Waldo has lost his car keys! He's not using a very efficient search;
-
- ==> reactor (probability) <==
- There is a reactor in which a reaction is to take place. This reaction
-
- ==> roulette (probability) <==
- You are in a game of Russian roulette, but this time the gun (a 6
-
- ==> transitivity (probability) <==
- Can you number dice so that die A beats die B beats die C beats die A?
-
- ==> icecubes (real-life) <==
- You have an old-fashioned refrigerator with a small freezer compartment
-
- ==> microwave (real-life) <==
- Every morning when I warm my milk for breakfast, I put one cup of milk
-
- ==> books/bloopers (references) <==
- What are some errors made in puzzle books?
-
- ==> books/masquerade (references) <==
- What is the solution to _Masquerade_ by Kit Williams?
-
- ==> books/maze (references) <==
- What is the solution to _Maze_ by Christopher Manson?
-
- ==> books/treasure (references) <==
- What is the solution to _Treasure_ by Dr. Crypton?
-
- ==> books/unnamed (references) <==
- What is the solution to the unnamed book by Kit Williams?
-
- ==> faq (references) <==
- Where should I look if I can't find the answer here?
-
- ==> magazines (references) <==
- What magazines and journals contain puzzles?
-
- ==> organizations (references) <==
- What organizations exist for puzzle lovers?
-
- ==> series.00 (series) <==
- Are "complete this series" problems well defined?
-
- ==> series.01 (series) <==
- M, N, B, D, P ?
-
- ==> series.02 (series) <==
- H, H, L, B, B, C, N, O, F ?
-
- ==> series.03 (series) <==
- W, A, J, M, M, A, J?
-
- ==> series.03a (series) <==
- G, J, T, J, J, J, A, M, W, J, J, Z, M, F, J, ?
-
- ==> series.03b (series) <==
- A, J, B, C, G, T, C, V, J, T, D, F, K, B, H, ?
-
- ==> series.03c (series) <==
- M, A, M, D, E, L, R, H, ?
-
- ==> series.04 (series) <==
- A, E, H, I, K, L, ?
-
- ==> series.05 (series) <==
- A B C D E F G H?
-
- ==> series.06 (series) <==
- Z, O, T, T, F, F, S, S, E, N?
-
- ==> series.06a (series) <==
- F, S, T, F, F, S, ?
-
- ==> series.07 (series) <==
- 1, 1 1, 2 1, 1 2 1 1, ...
-
- ==> series.08a (series) <==
- G, L, M, B, C, L, M, C, F, S, ?
-
- ==> series.08b (series) <==
- A, V, R, R, C, C, L, L, L, E, ?
-
- ==> series.09a (series) <==
- S, M, S, S, S, C, P, P, P, ?
-
- ==> series.09b (series) <==
- M, S, C, P, P, P, S, S, S, ?
-
- ==> series.10 (series) <==
- D, P, N, G, C, M, M, S, ?
-
- ==> series.11 (series) <==
- R O Y G B ?
-
- ==> series.12 (series) <==
- A, T, G, C, L, ?
-
- ==> series.13 (series) <==
- M, V, E, M, J, S, ?
-
- ==> series.14 (series) <==
- A, B, D, O, P, ?
-
- ==> series.14a (series) <==
- A, B, D, E, G, O, P, ?
-
- ==> series.15 (series) <==
- A, E, F, H, I, ?
-
- ==> series.16 (series) <==
- A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, X, Y?
-
- ==> series.17 (series) <==
- T, P, O, F, O, F, N, T, S, F, T, F, E, N, S, N?
-
- ==> series.18 (series) <==
- 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, ___ , 100, 121, 10000
-
- ==> series.19 (series) <==
- 0 01 01011 0101101011011 0101101011011010110101101101011011 etc.
-
- ==> series.20 (series) <==
- 1 2 5 16 64 312 1812 12288
-
- ==> series.21 (series) <==
- 5, 6, 5, 6, 5, 5, 7, 5, ?
-
- ==> series.22 (series) <==
- 3 1 1 0 3 7 5 5 2 ?
-
- ==> series.23 (series) <==
- 22 22 30 13 13 16 16 28 28 11 ?
-
- ==> series.24 (series) <==
- What is the next letter in the sequence: W, I, T, N, L, I, T?
-
- ==> series.25 (series) <==
- 1 3 4 9 10 12 13 27 28 30 31 36 37 39 40 ?
-
- ==> series.26 (series) <==
- 1 3 2 6 7 5 4 12 13 15 14 10 11 9 8 24 25 27 26 ?
-
- ==> series.27 (series) <==
- 0 1 1 2 1 2 1 3 2 2 1 3 1 2 2 4 1 3 1 3 2 2 1 4 2 ?
-
- ==> series.28 (series) <==
- 0 2 3 4 5 5 7 6 6 7 11 7 13 9 8 8 17 8 19 9 10 13 23 9 10 ?
-
- ==> series.29 (series) <==
- 1 1 2 1 2 2 3 1 2 2 3 2 3 3 4 1 2 2 3 2 3 3 4 2 3 3 4 3 4 ?
-
- ==> series.30 (series) <==
- I I T Y W I M W Y B M A D
-
- ==> series.31 (series) <==
- 6 2 5 5 4 5 6 3 7
-
- ==> series.32 (series) <==
- 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1
-
- ==> series.33 (series) <==
- 2 12 360 75600
-
- ==> series.34 (series) <==
- 3 5 4 4 3 5 5 4 3
-
- ==> series.35 (series) <==
- 1 2 3 2 1 2 3 4 2 1 2 3 4 2 2 3
-
- ==> series.36 (series) <==
- ETIANMSURWDKGO
-
- ==> series.37 (series) <==
- 10^3 10^9 10^27 10^2 0 4 8 3
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- ==> area.codes (trivia) <==
- When looking at a map of the distribution of telephone area codes for
-
- ==> body.parts (trivia) <==
- Name ten body parts that are spelled with three letters. No slang words.
-
- ==> coincidence (trivia) <==
- Name some amazing coincidences.
-
- ==> eskimo.snow (trivia) <==
- How many words do the Eskimo have for snow?
-
- ==> federal.reserve (trivia) <==
- What is the pattern to this list:
-
- ==> jokes.self-referential (trivia) <==
- What are some self-referential jokes?
-
- ==> memory.tricks (trivia) <==
- When asked to name a color, many people answer "red." What are some other
-
- ==> quotations (trivia) <==
- Where can I find the source for a quotation?
-