Einstein's Riddle

[Brian Harvey]

"Boris Popov" <no-spam-popov at bigserver.com> writes:
>house         1 2 3 4 5
>color            yellow blue red green white
>nationality   norweigian dane brit german swede
>drink            water tea milk coffee beer
>smoke        dunhill blend pall mall prince bluemaster
>pet              cats horse birds fish dogs
>
>P.S. Did I have to write software to solve it ? :)

I can't resist being (apparently) first to post a computer program.
But it doesn't really belong in any of these newsgroups, because it's
written in Logo.

First get Berkeley Logo from ftp://ftp.cs.berkeley.edu/ucblogo/
(pick the one that matches your platform)

Then get the logic-puzzle-solver from
http://www.cs.berkeley.edu/~bh/logic-code/hybrid.lg

Then here's the part specific to this puzzle:

? po [einstein neighbor neighbor1]
to einstein
cleanup
category "position [1 2 3 4 5]
category "color [red green white yellow blue]
category "nationality [British Swedish Danish Norwegian German]
category "beverage [tea coffee milk beer water]
category "cigar [pallmall dunhill blend bluemaster prince]
category "pet [dog bird cat horse fish]
verify "British "red
verify "Swedish "dog
verify "Danish "tea
justbefore "green "white :position
verify "green "coffee
verify "pallmall "bird
verify "yellow "dunhill
verify 3 "milk
verify 1 "Norwegian
neighbor "blend "cat :position
neighbor "horse "dunhill :position
verify "bluemaster "beer
verify "German "prince
neighbor "Norwegian "blue :position
neighbor "blend "water :position
print []
solution
end

to neighbor :a :b :lineup
falsify :a :b
neighbor1 :lineup count :lineup
end

to neighbor1 :lineup :count
if :count=0 [stop]
foreach bl bf bf :lineup [implies :a first :lineup "true :b ? "false]
neighbor1 (lput first :lineup bf :lineup) :count-1
end

? solve [einstein]
category position [1 2 3 4 5]
category color [red green white yellow blue]
category nationality [British Swedish Danish Norwegian German]
category beverage [tea coffee milk beer water]
category cigar [pallmall dunhill blend bluemaster prince]
category pet [dog bird cat horse fish]
British red -> true
Swedish red -> false
Danish red -> false
Norwegian red -> false
German red -> false
green British -> false
white British -> false
yellow British -> false
blue British -> false
Swedish dog -> true
British dog -> false
red dog -> false
Danish dog -> false
Norwegian dog -> false
German dog -> false
bird Swedish -> false
cat Swedish -> false
horse Swedish -> false
fish Swedish -> false
Danish tea -> true
British tea -> false
red tea -> false
Swedish tea -> false
dog tea -> false
Norwegian tea -> false
German tea -> false
coffee Danish -> false
milk Danish -> false
beer Danish -> false
water Danish -> false
green 5 -> false
white 1 -> false
green coffee -> true
red coffee -> false
British coffee -> false
white coffee -> false
yellow coffee -> false
blue coffee -> false
5 coffee -> false
tea green -> false
Danish green -> false
milk green -> false
beer green -> false
water green -> false
pallmall bird -> true
dunhill bird -> false
blend bird -> false
bluemaster bird -> false
prince bird -> false
dog pallmall -> false
Swedish pallmall -> false
cat pallmall -> false
horse pallmall -> false
fish pallmall -> false
yellow dunhill -> true
red dunhill -> false
British dunhill -> false
green dunhill -> false
coffee dunhill -> false
white dunhill -> false
blue dunhill -> false
pallmall yellow -> false
bird yellow -> false
blend yellow -> false
bluemaster yellow -> false
prince yellow -> false
3 milk -> true
1 milk -> false
2 milk -> false
4 milk -> false
5 milk -> false
tea 3 -> false
Danish 3 -> false
coffee 3 -> false
green 3 -> false
white 4 -> false
beer 3 -> false
water 3 -> false
1 Norwegian -> true
2 Norwegian -> false
3 Norwegian -> false
milk Norwegian -> false
4 Norwegian -> false
5 Norwegian -> false
white Norwegian -> false
British 1 -> false
red 1 -> false
Swedish 1 -> false
dog 1 -> false
Danish 1 -> false
tea 1 -> false
German 1 -> false
blend cat -> false
horse dunhill -> false
yellow horse -> false
bluemaster beer -> true
pallmall beer -> false
bird beer -> false
dunhill beer -> false
yellow beer -> false
blend beer -> false
prince beer -> false
tea bluemaster -> false
Danish bluemaster -> false
coffee bluemaster -> false
green bluemaster -> false
milk bluemaster -> false
3 bluemaster -> false
water bluemaster -> false
German prince -> true
British prince -> false
red prince -> false
Swedish prince -> false
dog prince -> false
Danish prince -> false
tea prince -> false
Norwegian prince -> false
1 prince -> false
pallmall German -> false
bird German -> false
dunhill German -> false
yellow German -> false
blend German -> false
bluemaster German -> false
beer German -> false
Norwegian blue -> false
1 blue -> false
blue 3 -> false
milk blue -> false
blue 4 -> false
blend water -> false


  Assuming 1 yellow
  1 yellow -> true
  2 yellow -> false
  dunhill 2 -> false
  3 yellow -> false
  milk yellow -> false
  dunhill milk -> false
  3 dunhill -> false
  4 yellow -> false
  dunhill 4 -> false
  5 yellow -> false
  dunhill 5 -> false
  1 dunhill -> true
  Norwegian dunhill -> true
  Swedish dunhill -> false
  dog dunhill -> false
  yellow dog -> false
  Swedish yellow -> false
  Danish dunhill -> false
  tea dunhill -> false
  water dunhill -> true
  pallmall water -> false
  bird water -> false
  prince water -> false
  German water -> false
  yellow water -> true
  red water -> false
  British water -> false
  white water -> false
  blue water -> false
  Swedish water -> false
  Norwegian water -> true
  1 water -> true
  2 water -> false
  4 water -> false
  5 water -> false
  dog water -> false
  coffee 1 -> false
  green 1 -> false
  Norwegian green -> false
  yellow Norwegian -> true
  beer Norwegian -> false
  bluemaster Norwegian -> false
  1 bluemaster -> false
  beer 1 -> false
  horse Norwegian -> false
  1 horse -> false
  water horse -> false
  blend Norwegian -> false
  1 blend -> false
  pallmall Norwegian -> false
  bird Norwegian -> false
  1 bird -> false
  pallmall 1 -> false
  coffee Norwegian -> false
  Danish yellow -> false
  tea yellow -> false
  white 2 -> false
  blend 4 -> false
  blend 3 -> false
  milk blend -> false
  horse 4 -> false
  horse 3 -> false
  milk horse -> false

    Assuming 5 beer
    5 beer -> true
    2 beer -> false
    bluemaster 2 -> false
    4 beer -> false
    bluemaster 4 -> false
    5 bluemaster -> true
    pallmall 5 -> false
    bird 5 -> false
    blend 5 -> false
    2 blend -> true
    white blend -> false
    pallmall 2 -> false
    bird 2 -> false
    prince 2 -> false
    German 2 -> false
    cat 2 -> false
    cat 5 -> false
    bluemaster cat -> false
    beer cat -> false
    cat 4 -> false
    prince 5 -> false
    German 5 -> false
    tea 5 -> false
    Danish 5 -> false

      Assuming 5 Swedish
      5 Swedish -> true
      2 Swedish -> false
      blend Swedish -> false
      bluemaster Swedish -> true
      beer Swedish -> true
      coffee Swedish -> false
      green Swedish -> false
      German green -> true
      prince green -> true
      pallmall green -> false
      bird green -> false
      coffee bird -> false
      pallmall coffee -> false
      blend green -> false
      2 green -> false
      4 green -> true
      cat green -> false
      coffee cat -> false
      horse green -> false
      coffee horse -> false
      red 4 -> false
      British 4 -> false
      coffee 4 -> true
      tea 4 -> false
      Danish 4 -> false
      2 Danish -> true
      blend Danish -> true
      pallmall Danish -> false
      bird Danish -> false
      British bird -> true
      red bird -> true
      white bird -> false
      pallmall white -> false
      blue bird -> false
      pallmall blue -> false
      red pallmall -> true
      British pallmall -> true
      4 pallmall -> false
      3 pallmall -> true
      milk pallmall -> true
      tea pallmall -> false
      blend tea -> true
      2 tea -> true
      cat tea -> false
      Danish cat -> false
      bird tea -> false
      milk bird -> true
      3 bird -> true
      4 bird -> false
      dog 3 -> false
      Swedish 3 -> false
      milk Swedish -> false
      dog milk -> false
      cat 3 -> false
      1 cat -> true
      yellow cat -> true
      red cat -> false
      British cat -> false
      white cat -> false
      blue cat -> false
      water cat -> true
      milk cat -> false
      Norwegian cat -> true
      German cat -> false
      prince cat -> false
      dunhill cat -> true
      fish dunhill -> false
      1 fish -> false
      yellow fish -> false
      water fish -> false
      Norwegian fish -> false
      fish 3 -> false
      milk fish -> false
      white 3 -> false
      red 3 -> true
      British 3 -> true
      German 3 -> false
      prince 3 -> false
      4 prince -> true
      horse prince -> false
      fish prince -> true
      milk prince -> false
      coffee prince -> true
      blue prince -> false
      German blue -> false
      white prince -> false
      bluemaster white -> true
      5 white -> true
      beer white -> true
      tea white -> false
      Danish white -> false
      blue Danish -> true
      Swedish blue -> false
      dog blue -> false
      white Swedish -> true
      4 Swedish -> false
      German 4 -> true
      dog 4 -> false
      fish 4 -> true
      2 fish -> false
      blend fish -> false
      5 fish -> false
      beer fish -> false
      bluemaster fish -> false
      green fish -> true
      red fish -> false
      British fish -> false
      white fish -> false
      blue fish -> false
      Danish fish -> false
      German fish -> true
      tea fish -> false
      coffee fish -> true
      dog coffee -> false
      beer dog -> true
      5 dog -> true
      2 dog -> false
      blend dog -> false
      bluemaster dog -> true
      green dog -> false
      white dog -> true
      horse white -> false
      milk white -> false
      red milk -> true
      British milk -> true
      German milk -> false
      coffee German -> true
      horse German -> false
      white German -> false
      2 coffee -> false
      blend coffee -> false
      beer British -> false
      5 British -> false
      bluemaster British -> false
      red bluemaster -> false
      5 red -> false
      beer red -> false
      horse British -> false
      Danish horse -> true
      tea horse -> true
      beer horse -> false
      5 horse -> false
      2 horse -> true
      blend horse -> true
      bluemaster horse -> false
      British blend -> false
      red blend -> false
      blue blend -> true
      bluemaster blue -> false
      5 blue -> false
      2 blue -> true
      beer blue -> false
      tea blue -> true
      red 2 -> false
      British 2 -> false
      horse blue -> true
      red horse -> false

1 yellow Norwegian water dunhill cat
2 blue Danish tea blend horse
3 red British milk pallmall bird
4 green German coffee prince fish
5 white Swedish beer bluemaster dog