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- Frequently Asked Questions (FAQS);faqs.463
-
-
-
- ==> english/repeat.p <==
- What is a sentence containing the most repeated words, without:
- using quotation marks,
- using proper names,
- using a language other than English,
- anything else distasteful.
-
- ==> english/repeat.s <==
- Five "had"s in a row:
-
- The parents were unable to conceive, so they hired someone else to
- be a surrogate.
-
- The parents had had a surrogate have their child.
-
- The parents had had had their child.
-
- The child had had no breakfast.
-
- The child whose parents had had had had had no breakfast.
-
- ==> english/repeated.words.p <==
- What is a sentence with the same word several times repeated?
-
- ==> english/repeated.words.s <==
- It is true for all that, that that that that that that signifies, is not
- the one to which I refer.
-
- Here are some steps to understanding the entire sentence:
- That is not the one to which I refer.
- That (that that that signifies) is not the one to which I refer.
- That that that that that that signifies, is not the one to which I refer.
-
- In Annamite:
- Ba ba ba ba.
- (Three ladies gave a box on the ear to the favorite of the Prince.)
-
- ==> english/rhyme.p <==
- What English words are hard to rhyme?
-
- "Rhyme is the identity in sound of an accented vowel in a word...and
- of all consonantal and vowel sounds following it; with a difference in
- the sound of the consonant immediately preceding the accented vowel."
- (From The Complete Rhyming Dictionary by Clement Wood). Appropriately
- Wood says a couple of pages later, "If a poet commences, 'October is
- the wildest month' he has estopped himself from any rhyme; since
- "month" has no rhyme in English."
-
- ==> english/rhyme.s <==
- NI3 = Merriam-Webster's Third New International Dictionary
- NI2 = Merriam-Webster's New International Dictionary, Second Edition
- RHD = Random House Unabridged Dictionary
- + means slang, foreign, obsolete, dialectical, etc.
-
- Word Rhyme Assonance
- --------------- --------------------------------------- --------------------
- aitch brache (NI2+), taich (NI2+) naish
- angry unangry (NI2+) aggry
- angst lanx
- beards weirds
- breadth death
- bulb pulp
- carpet charpit
- chimney timne, polymny (NI2+)
- cusp wusp (NI2) bust
- depth stepped
- eighth faith
- else belts
- exit direxit (RHD+) sexist
- fiends teinds, piends
- filched hilched (NI3+), milched (NI2) zilch
- filth spilth, tilth
- fifth drift
- film pilm (NI3+) kiln
- fluxed luxed (NI3+), muxed (NI3+) ducked
- glimpsed rinsed
- gospel hostile
- gulf pulse
- jinxed outminxed (?) blinked
- leashed niched, tweesht (NI2+)
- liquid wicked
- mollusk smallest
- mouthed southed
- month grumph
- mulcts bulks
- mulched gulched (NI3+) bulged
- ninth pint
- oblige bides
- oomph sumph (NI3+)
- orange sporange
- pint jint (NI2+) bind
- poem phloem, proem
- pregnant regnant
- purple curple (NI3+), hirple (NI3+)
- puss schuss
- rhythm smitham
- scalds balds, caulds (NI3+), faulds (NI3+)
- scarce clairce (NI2), hairse (NI2+) cares
- sculpts gulps
- silver chilver (NI3+)
- sixth kicks
- spirit squiret (NI2+)
- tenth nth bent
- tsetse baronetcy, intermezzi, theetsee
- tuft yuft
- twelfth health
- widow kiddo
- width bridge
- window indo, lindo
- wolf bulls
-
- ==> english/self.ref.letters.p <==
- Construct a true sentence of the form: "This sentence contains _ a's, _ b's,
- _ c's, ...," where the numbers filling in the blanks are spelled out.
-
- ==> english/self.ref.letters.s <==
- A little history of the problem, culled from the pages of _Metamagical
- Themas_, Hofstadter's collection of his _Scientific American_ columns.
- First mention of it is in the Jan. '82 column, a followup to one on self-
- referential sentences. Lee Sallows opened the field with a sentence that
- began "Only the fool would take trouble to verify that his sentence was
- composed of ten a's ...." etc.
-
- Then in the addendum to the Jan.'83 column on viral sentences, Hofstadter
- quotes Sallows describing his Pangram Machine, "a clock-driven cascade of
- sixteen Johnson-counters," to tackle the problem. An early success was:
- "This pangram tallies five a's, one b, one c, two d's, twenty-
- eight e's, eight f's, six g's, eight h's, thirteen i's, one j,
- one k, three l's, two m's, eighteen n's, fifteen o's, two p's,
- one q, seven r's, twenty-five s's, twenty-two t's, four u's, four
- v's, nine w's, two x's, four y's, and one z."
-
- Sallows wagered ten guilders that no-one could create a perfect self-
- documenting sentence beginning, "This computer-generated pangram contains
- ...." within ten years.
-
- It was solved very quickly, after Sallows' challenge appeared in Dewdny's
- Oct. '84 SA column. Larry Tesler solved it by a method Hofstadter calls
- "Robinsonizing," which involves starting with an arbitrary set of values
- for each letter, getting the true values when the sentence is made, and
- plugging the new values back in, making a feedback loop. Eventually, you
- can zero in on a set of values that work. Tesler's sentence:
- This computer-generated pangram contains six a's, one b, three
- c's, three d's, thirty-seven e's, six f's, three g's, nine h's,
- twelve i's, one j, one k, two l's, three m's, twenty-two n's,
- thirteen o's, three p's, one q, fourteen r's, twenty-nine s's,
- twenty-four t's, five u's, six v's, seven w's, four x's, five
- y's, and one z.
-
- The method of solution (called "Robinsonizing," after the logician Raphael
- Robinson) is as follows:
- 1) Fix the count of a's.
- 2) Fix the count of b's.
- 3) Fix the count of c's.
- ...
- 26) Fix the count of z's.
- Then, if the sentence is still wrong, go back to step 1.
-
- Most attempts will fall into long loops (what Hofstadter calls attractive
- orbits), but with a good computer program, it's not too hard to find a
- Robinsonizing sequence that zeros in on a fixed set of values.
-
- The February and May 1992 _Word Ways_ have articles on this subject,
- titled "In Quest of a Pangram, (Part 1)" by Lee Sallows. It tells of his
- search for a self-referential pangram of the form, "This pangram
- contains _ a's, ..., and one z." (He built special hardware to search
- for them.) Two such pangrams given in the article are:
-
- This pangram lists four a's, one b, one c, two d's,
- twenty-nine e's, eight f's, three g's, five h's, eleven i's,
- one j, one k, three l's, two m's twenty-two n's, fifteen o's,
- two p's, one q, seven r's, twenty-six s's, nineteen t's, four
- u's, five v's, nine w's, two x's, four y's, and one z.
-
- This pangram contains four a's, one b, two c's, one d, thirty
- e's, six f's, five g's, seven h's, eleven i's, one j, one k,
- two l's, two m's eighteen n's, fifteen o's, two p's, one q,
- five r's, twenty-seven s's, eighteen t's, two u's, seven v's,
- eight w's, two x's, three y's, & one z.
-
- It also contains one in Dutch by Rudy Kousbroek:
-
- Dit pangram bevat vijf a's, twee b's, twee c's, drie d's,
- zesenveertig e's, vijf f's, vier g's, twee h's, vijftien i's,
- vier j's, een k, twee l's, twee m's, zeventien n's, een o,
- twee p's, een q, zeven r's, vierentwintig s's, zestien t's,
- een u, elf v's, acht w's, een x, een y, and zes z's.
-
- References:
- Dewdney, A.K. Scientific American, Oct. 1984, pp 18-22.
- Sallows, L.C.F. Abacus, Vol.2, No.3, Spring 1985, pp 22-40.
- Sallows, L.C.F. Word Ways, Feb. & May 1992
- Hofstadter, D. Scientific American, Jan. 1982, pp 12-17.
-
- ==> english/self.ref.numbers.p <==
- What true sentence has the form: "There are _ 0's, _ 1's, _ 2's, ...,
- in this sentence"?
-
- ==> english/self.ref.numbers.s <==
- There are 1 0's, 7 1's, 3 2's, 2 3's, 1 4's, 1 5's, 1 6's, 2 7's, 1 8's,
- and 1 9's in this sentence.
-
- There are 1 0's, 11 1's, 2 2's, 1 3's, 1 4's, 1 5's, 1 6's, 1 7's, 1 8's
- and 1 9's in this sentence.
-
- ==> english/self.ref.words.p <==
- What sentence describes its own word, syllable and letter count?
-
- ==> english/self.ref.words.s <==
- This sentence contains ten words, eighteen syllables, and sixty-four letters.
-
- ==> english/sentence.p <==
- Find a sentence with words beginning with the letters of the alphabet, in order.
-
- ==> english/sentence.s <==
- After boxes containing dynamite exploded furiously
- generating hellish inferno jet killing laboring miners,
- novice operator, paralyzed, quickly refuses surgical treatment
- until veteran workers x-ray youth zealously.
-
- A big cuddly dog emitted fierce growls happily ignoring joyful kids licking
- minute nuts on pretty queer rotten smelly toadstalls underneath vampires
- who x-rayed young zombies.
-
- ==> english/snowball.p <==
- Construct the longest coherent sentence you can such that the nth
- word is n letters long.
-
- ==> english/snowball.s <==
- I
- do
- not
- know
- where
- family
- doctors
- acquired
- illegibly
- perplexing
- handwriting;
- nevertheless,
- extraordinary
- pharmaceutical
- intellectuality,
- counterbalancing
- indecipherability,
- transcendentalizes
- intercommunications'
- incomprehensibleness.
-
- ==> english/spoonerisms.p <==
- List some exceptional spoonerisms.
-
- ==> english/spoonerisms.s <==
- Original by Spooner himself:
-
- I am afraid you have tasted the whole worm, and must
- therefore take the next town drain.
-
- Some years ago in the Parliament, a certain member known for his quick and
- rapier wit, cut across a certain other member who was trying to make some
- bad joke. He called him a "Shining Wit" then apologized for making a
- Spoonerism.
-
- Another famous broadcast fluff was on the Canadian Broadcasting
- Corporation, which an announcer identified as the "Canadian
- Broadcorping Castration."
-
- Oh yes, another radio announcer one that has sort of crept into
- common English usage is "one swell foop".
-
- A friend of mine had just eaten dinner in the school
- cafeteria, and he didn't look very happy. Another of
- my friends said, "John, what's wrong?" Knowing exactly
- what he was saying, he said, "It's the bound grief I
- had for dinner!"
-
- A radio announcer, talking about a royal visit (or some such) said the
- visitor would be greeted with a "twenty one sun galoot".
-
- There are several fractured fables based on spoonerisms, such as:
-
- A king on a desert island was so beloved by his people, they decided to
- give him a very special gift for the anniversary of his coronation. So
- after much thought, they decided to make him a throne out of seashells,
- which were plentiful on the island. And when it was finished, they
- presented it to the king, who loved it. But he soon discovered it was
- very uncomfortable to sit on. So he told his subjects it was too
- special to use everyday (so as not to hurt their feelings) and put it in
- the attic of his palace (which was, of course, a hut like all the other
- dwellings on the island), planning to use it just for special occasions.
- But that night, it fell through the ceiling of his bedroom and landed
- on top of him, killing him instantly. And the moral of the story is:
- Those who live in grass houses shouldn't stow thrones!
-
- ==> english/states.p <==
- What long words have all bigrams either a postal state code or its reverse?
-
- ==> english/states.s <==
- 10 paramarine
- 10 indentment
- 10 cacocnemia
- 9 amendment
- 9 paramimia
- 9 paramenia
- 9 paralinin
- 9 paralalia
- 9 palilalia
- 9 palapalai
- 8 scalawag
- 8 memorial
-
- Disallowing reversals of state codes the longest common ones are:
-
- 8 malarial
- 7 malaria
- 6 scalar
- 6 marine
- 5 flaky
-
- Terry Donahue
-
- ==> english/telegrams.p <==
- Since telegrams cost by the word, phonetically similar messages can be cheaper.
- See if you can decipher these extreme cases:
-
- UTICA CHANSON MIGRATE INVENTION ANNUAL KNOBBY SORRY IN FACTUAL BEEN CLOVER.
-
- WEED LICHEN ICE CHEST FOREARM OTHER DISGUISE DELIMIT.
-
- CANCEL MYOCARDIA ITS INFORMAL FUNCTION.
-
- YEARN AFFIX, LOST UKASE, UGANDA JAIL, CONSERVE TENURES YACHT APPEAL.
-
- EYELET SHEILA INDIA HOUSE SHEILAS TURKEY.
-
- BOB STILT SEA, CANTANKEROUS BOAT, HUMUS GOAD IMMORTAL DECOS GUARD.
-
- MARY SINBAD SHEER TOURNEY AUGUSTA WIND NOCTURNE TOOTHBRUSH.
-
- WHINE YOSEMITE NAMES SOY CAN PHILATELIST.
-
- ALBEIT DETRACT UNIVERSE EDIFY MUSTAFA TICKET TICKET IN.
-
- ==> english/telegrams.s <==
- These are from an old "Games" magazine:
-
- UTICA CHANSON MIGRATE INVENTION ANNUAL KNOBBY SORRY IN FACTUAL BEEN CLOVER.
- You take a chance on my great invention and you'll not be sorry.
- In fact, you'll be in clover.
-
- WEED LICHEN ICE CHEST FOREARM OTHER DISGUISE DELIMIT.
- We'd like a nice chest for our mother; the sky's the limit.
-
- CANCEL MYOCARDIA ITS INFORMAL FUNCTION.
- Can't sell my ol' car dear; it's in for malfunction.
-
- YEARN AFFIX, LOST UKASE, UGANDA JAIL, CONSERVE TENURES YACHT APPEAL.
- You're in a fix. Lost your case. You goin' to jail.
- Can serve ten years. You ought to appeal.
-
- EYELET SHEILA INDIA HOUSE SHEILAS TURKEY.
- I let Sheila in their house; she lost her key.
-
- BOB STILT SEA, CANTANKEROUS BOAT, HUMUS GOAD IMMORTAL DECOS GUARD.
- Bob's still at sea; can't anchor his boat. You must go to him
- or tell the coast guard.
-
- MARY SINBAD SHEER TOURNEY AUGUSTA WIND NOCTURNE TOOTHBRUSH.
- Mary's in bed; she hurt her knee. A gust of wind
- knocked her into the brush.
-
- WHINE YOSEMITE NAMES SOY CAN PHILATELIST.
- Why don't you (why'n'ya) send me the names, so I can
- fill out a list.
-
- ALBEIT DETRACT UNIVERSE EDIFY MUSTAFA TICKET TICKET IN.
- I'll be at the track and I have a receipt if I must have a ticket to
- get in.
-
- ==> english/trivial.p <==
- Consider the free non-abelian group on the twenty-six letters of the
- alphabet with all relations of the form <word1> = <word2>, where <word1>
- and <word2> are homophones (i.e. they sound alike but are spelled
- differently). Show that every letter is trivial.
-
- For example, be = bee, so e is trivial.
-
- ==> english/trivial.s <==
- be = bee ==> e is trivial;
- ail = ale ==> i is trivial;
- week = weak ==> a is trivial;
- lie = lye ==> y is trivial;
- to = too ==> o is trivial;
- two = to ==> w is trivial;
- hour = our ==> h is trivial;
- faggot = fagot ==> g is trivial;
- bowl = boll ==> l is trivial;
- gell = jel ==> j is trivial;
- you = ewe ==> u is trivial;
- damn = dam ==> n is trivial;
- limb = limn ==> b is trivial;
- bass = base ==> s is trivial;
- cede = seed ==> c is trivial;
- knead = need ==> k is trivial;
- add = ad ==> d is trivial;
- awful = offal ==> f is trivial;
- gram = gramme ==> m is trivial;
- grip = grippe ==> p is trivial;
- cue = queue ==> q is trivial;
- carrel = carol ==> r is trivial;
- butt = but ==> t is trivial;
- lox = locks ==> x is trivial;
- tsar = czar ==> z is trivial;
- vlei = flay ==> v is trivial.
-
- For a related problem, see _The Jimmy's Book_ (_The American Mathematical
- Monthly_, Vol. 93, Num. 8 (Oct. 1986), p. 637):
-
- Consider the free group on twenty-six letters A, ..., Z. Mod out by
- the relation that defines two words to be equivalent if (a) one is a
- permutation of the other and (b) each appears as a legitimate English
- word in the dictionary. Identify the center of this group.
-
- -- clong@remus.rutgers.edu (Chris Long)
-
- ==> english/weird.p <==
- Make a sentence containing only words that violate the "i before e" rule.
-
- ==> english/weird.s <==
- From the May, 1990 _Word Ways_:
-
- That is IE - Or, Is That EI?
-
- by Paul Leopold
- Stockholm, Sweden
-
- "Seeing wherein neither weirdly-veiled sovereign deigned
- agreeing, their feisty heirs, leisurely eyeing eight heinous
- deity-freightened reindeer sleighs, counterfeited spontaneity,
- freeing rein (reveille, neighing!); forfeited obeisance,
- fleeing neighborhood. Kaleidoscopically-veined foreign
- heights being seized, either reigned, sleight surfeited,
- therein; reinvented skein-dyeing; reiteratedly inveighed,
- feigning weighty seismological reinforcement."
-
- The above passage appears in a book on the ecological conservation
- measures of the enlightened plutocracies of antiquity, Ancient
- Financier Aristocracies' Conscientious Scientific Species Policies,
- by Creighton Leigh Peirce and Keith Leiceister Reid. . . .
-
- Any beings decreeing such ogreish, albeit nonpareil,
- homogeneity must be nucleic protein-deficient from sauteing
- pharmacopoeial caffeine and codeine!
-
- From an 'fgrep cie /usr/dict/words', with similiar words removed.
- ancient coefficient concierge conscience conscientious deficient efficient
- financier glacier hacienda Muncie omniscient proficient science
- Societe(?) society species sufficient
-
- A search through Webster's on-line dictionary produced the following exceptions:
-
- Word: *cie*
- Possible matches are:
- 1. -facient 2. abortifacient 3. ancien regime
- 4. ancient 5. ancientry 6. boccie
- 7. cenospecies 8. christian science 9. coefficient
- 10. concierge 11. conscience 12. conscience money
- 13. conscientious 14. conscientious objector15. deficiency
- 16. deficiency disease 17. deficient 18. domestic science
- 19. earth science 20. ecospecies 21. efficiency
- 22. efficiency engineer 23. efficient 24. facies
- 25. fancier 26. financier 27. genospecies
- 28. geoscience 29. glacier 30. glacier theory
- 31. habeas corpus ad subjiciendum32. hacienda 33. inconscient
- 34. inefficiency 35. inefficient 36. insufficience
- 37. insufficiency 38. insufficient 39. international scientific vocabulary
- 40. library science 41. liquefacient 42. mental deficiency
- 43. mutafacient 44. natural science 45. nescience
- 46. omniscience 47. omniscient 48. physical science
- 49. political science 50. precieux 51. prescience
- 52. prescientific 53. prima facie 54. proficiency
- 55. proficient 56. pseudoscience 57. rubefacient
- 58. science 59. science fiction 60. scient
- 61. sciential 62. scientific 63. scientific method
- 64. scientism 65. scientist 66. scientistic
- 67. secret society 68. self-sufficiency 69. self-sufficient
- 70. social science 71. social scientist 72. societal
- 73. society 74. society verse 75. somnifacient
- 76. specie 77. species 78. stupefacient
- 79. sub specie aeternitatis80. subspecies 81. sufficiency
- 82. sufficient 83. sufficient condition 84. superficies
- 85. type species 86. unscientific 87. valenciennes
- 88. vers de societe
-
- ==> english/word.boundaries.p <==
- List some sentences that can be radically altered by changing word boundaries
- and punctuation.
-
- ==> english/word.boundaries.s <==
- Issues topping our mail: manslaughter.
- Is Sue stopping our mailman's laughter?
-
- The real ways I saw it.
- There always is a wit.
-
- You read evil tomes, Tim, at Ed's issue.
- "You're a devil, Tom!" estimated sis Sue.
-
- ==> english/word.torture.p <==
- What is the longest word all of whose contiguous subsequences are words?
-
- ==> english/word.torture.s <==
- This problem was discussed in _Word Ways_ in 1974-5. In August 1974,
- Ralph Beaman, in an article titled "Word Torture", offered the word
- SHADES, from which one obtains HADES, SHADE; ADES, HADE, SHAD; DES, ADE,
- HAD, SHA; ES, DE, AD, HA, SH; S, E, D, A, H. All of these are words
- given in Webster's Third.
-
- Since that time, a serious search has been launched for a seven-letter
- word. The near misses so far are:
- Date Person Word Missing
- Aug 74 Ralph Beaman GAMINES INES, GAMI, NES, INE
- Nov 74 Dmitri Borgmann ABASHED INE, NES, ABASHE, BASHE, ASHE (all in OED)
- May 75 David Robinson GUNITES GU, GUNIT (using Webster's Second)
- May 75 David Robinson ETAMINE ETAMI, TAMI (using Webster's Second)
- May 75 Ralph Beaman MORALES RAL (using Webster's Second)
- Aug 75 Tom Pulliam SHEAVES EAV (using Webster's Second)
-
- Webster's Second has been used for most of the attempts since it
- contains so many more words than Webster's Third. The seven-letter
- plateau remains to be achieved.
-
- ==> games/chess/knight.control.p <==
- How many knights does it take to attack or control the board?
-
- ==> games/chess/knight.control.s <==
- Fourteen knights are required to attack every square:
-
- 1 2 3 4 5 6 7 8
- ___ ___ ___ ___ ___ ___ ___ ___
- h | | | | | | | | |
- --- --- --- --- --- --- --- ---
- g | | | N | N | N | N | | |
- --- --- --- --- --- --- --- ---
- f | | | | | | | | |
- --- --- --- --- --- --- --- ---
- e | | N | N | | | N | N | |
- --- --- --- --- --- --- --- ---
- d | | | | | | | | |
- --- --- --- --- --- --- --- ---
- c | | N | N | N | N | N | N | |
- --- --- --- --- --- --- --- ---
- b | | | | | | | | |
- --- --- --- --- --- --- --- ---
- a | | | | | | | | |
- --- --- --- --- --- --- --- ---
-
- Three knights are needed to attack h1, g2, and a8; two more for b1, a2,
- and b3, and another two for h7, g8, and f7.
-
- The only alternative pattern is:
-
- 1 2 3 4 5 6 7 8
- ___ ___ ___ ___ ___ ___ ___ ___
- h | | | | | | | | |
- --- --- --- --- --- --- --- ---
- g | | | N | | | N | | |
- --- --- --- --- --- --- --- ---
- f | | | N | N | N | N | | |
- --- --- --- --- --- --- --- ---
- e | | | | | | | | |
- --- --- --- --- --- --- --- ---
- d | | | N | N | N | N | | |
- --- --- --- --- --- --- --- ---
- c | | N | N | | | N | N | |
- --- --- --- --- --- --- --- ---
- b | | | | | | | | |
- --- --- --- --- --- --- --- ---
- a | | | | | | | | |
- --- --- --- --- --- --- --- ---
-
- Twelve knights are needed to control (attack or occupy) the board:
-
- 1 2 3 4 5 6 7 8
- ___ ___ ___ ___ ___ ___ ___ ___
- a | | | | | | | | |
- --- --- --- --- --- --- --- ---
- b | | | N | | | | | |
- --- --- --- --- --- --- --- ---
- c | | | N | N | | N | N | |
- --- --- --- --- --- --- --- ---
- d | | | | | | N | | |
- --- --- --- --- --- --- --- ---
- e | | | N | | | | | |
- --- --- --- --- --- --- --- ---
- f | | N | N | | N | N | | |
- --- --- --- --- --- --- --- ---
- g | | | | | | N | | |
- --- --- --- --- --- --- --- ---
- h | | | | | | | | |
- --- --- --- --- --- --- --- ---
-
- Each knight can control at most one of the twelve squares a1, b1, b2,
- h1, g1, g2, a8, b8, b7, h8, g8, g7. This position is unique up to
- reflection.
-
- References
- Martin Gardner, _Mathematical Magic Show_.
-
- ==> games/chess/mutual.check.p <==
- What position is a stalemate for both sides and is reachable in a legal game
- (including the requirement to prevent check)?
-
- ==> games/chess/mutual.check.s <==
- Put the following configuration in one corner:
-
- |
- | x
- | P x
- |B P P
- |K R B
- +---------
-
- ("x" is a Black pawn), and the same with colors reversed in the h8
- corner.
-
- --Noam D. Elkies (elkies@zariski.harvard.edu)
- Dept. of Mathematics, Harvard University
-
- ==> games/chess/mutual.stalemate.p <==
- What's the minimal number of pieces in a legal mutual stalemate?
-
- ==> games/chess/mutual.stalemate.s <==
- 6.
-
- W Kh8 e6 f7 h7 B Kf8 e7
- W Kb1 B Ka3 b2 b3 b4 a4
- W Kf1 B Kh1 Bg1 f2 f3 h2
-
- ==> games/chess/queens.p <==
- How many ways can eight queens be placed so that they control the board?
-
- ==> games/chess/queens.s <==
- 92. The following program uses a backtracking algorithm to count positions:
-
- #include <stdio.h>
-
- static int count = 0;
-
- void try(int row, int left, int right) {
- int poss, place;
- if (row == 0xFF) ++count;
- else {
- poss = ~(row|left|right) & 0xFF;
- while (poss != 0) {
- place = poss & -poss;
- try(row|place, (left|place)<<1, (right|place)>>1);
- poss &= ~place;
- }
- }
- }
-
- void main() {
- try(0,0,0);
- printf("There are %d solutions.\n", count);
- }
- --
- Tony Lezard IS tony@mantis.co.uk OR tony%mantis.co.uk@uknet.ac.uk
- OR EVEN arl10@phx.cam.ac.uk if all else fails.
-
- ==> games/chess/size.of.game.tree.p <==
- How many different positions are there in the game tree of chess?
-
- ==> games/chess/size.of.game.tree.s <==
- Consider the following assignment of bit strings to square states:
-
- Square State Bit String
- ------ ----- --- ------
-
- Empty 0
- White Pawn 100
- Black Pawn 101
- White Rook 11111
- Black Rook 11110
- White Knight 11101
- Black Knight 11100
- White Bishop 11011
- Black Bishop 11010
- White Queen 110011
- Black Queen 110010
- White King 110001
- Black King 110000
-
- Record a position by listing the bit string for each of the 64 squares.
- For a position with all the pieces still on the board, this will take
- 164 bits. As pieces are captured, the number of bits needed goes down.
- As pawns promote, the number of bits go up. For positions where a King
- and Rook are in position to castle if castling is legal, we will need
- a bit to indicate if in fact castling is legal. Same for positions
- where an en-passant capture may be possible. I'm going to ignore these
- on the grounds that a more clever encoding of a position than the one
- that I am proposing could probably save as many bits as I need for these
- considerations, and thus conjecture that 164 bits is enough to encode a
- chess position.
-
- This gives an upper bound of 2^164 positions, or 2.3x10^49 positions.
-
- Jurg Nievergelt, of ETH Zurich, quoted the number 2^70 (or about 10^21) in
- e-mail, and referred to his paper "Information content of chess positions",
- ACM SIGART Newsletter 62, 13-14, April 1977, to be reprinted in "Machine
- Intelligence" (ed Michie), to appear 1990.
-
- Note that this latest estimate, 10^21, is not too intractable:
- 10^7 computers running at 10^7 positions per second could scan those
- in 10^7 seconds, which is less than 6 months.
-
- In fact, suppose there is a winning strategy in chess for white. Suppose
- further that the strategy starts from a strong book opening, proceeds through
- middle game with only moves that DT would pick using the singular
- extension technique, and finally ends in an endgame that DT can analyze
- completely. The book opening might take you ten moves into the game and
- DT has demonstarted its ability to analyze mates-in-20, so how many nodes
- would DT really have to visit? I suggest that by using external storage
- such a optical WORM memory, you could easily build up a transposition
- table for such a midgame. If DT did not find a mate, you could progressively
- expand the width of the search window and add to the table until it did.
- Of course there would be no guarantee of success, but the table built
- would be useful regardless. Also, you could change the book opening and
- add to the table. This project could continue indefinitely until finally
- it must solve the game (possibly using denser and denser storage media as
- technology advances).
-
- What do you think?
-
- -------
-
- I think you are a little bit too optimistic about the feasibility. Solving
- mate-in-19 when the moves are forcing is one thing, but solving mate-in-19
- when the moves are not forcing is another. Of course, human beings are no
- better at the latter task. But to solve the game in the way you described
- would seem to require the ability to handle the latter task. Anyway, we
- cannot really think about doing the sort of thing you described; DT is just a
- poor man's chess machine project (relatively speaking).
- --Hsu
-
- i dont think that you understand the numbers involved.
- the size of the tree is still VERY large compared to all
- the advances that you cite. (speed of DT, size of worms,
- endgame projects, etc) even starting a project will probably
- be a waste of time since the next advance will overtake it
- rather than augment it. (if you start on a journey to the
- stars today, you will be met there by humans)
- ken
-
- ==> games/cigarettes.p <==
- The game of cigarettes is played as follows:
- Two players take turns placing a cigarette on a circular table. The cigarettes
- can be placed upright (on end) or lying flat, but not so that it touches any
- other cigarette on the table. This continues until one person looses by not
- having a valid position on the table to place a cigarette.
-
- Is there a way for either of the players to guarantee a win?
-
- ==> games/cigarettes.s <==
- The first person wins by placing a cigarette at the center of the table,
- and then placing each of his cigarettes in a position symmetric (with
- respect to the center) to the place the second player just moved. If the
- second player could move, then symmetrically, so can the first player.
-