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100 islanders logic puzzle - what about a silent oracle?

Posted By: Walfinho
Date: Friday, 21 August 2009, at 6:21 p.m.

In Response To: 100 islanders logic puzzle - what about a silent oracle? (Gregg Cattanach)

it matters that the oracle says that there is at least one person with blue eyes. Up to the day everybody knows that others have blue eyes but not whether they themselves do. Now everybody knows that everybody knows. Just look at the case when there are only two blue eyed islanders: To none of the islanders the oracles statement is news. However, both blue eyed islanders know on the second day that they have blue eyes, because if there was only one islander with blue eyes that one would have killed himself. You can use induction from here and so the 10 islanders will know on the 10th day and commit suicide.

Messages In This Thread

• 100 islanders logic puzzle
  bob koca -- Friday, 21 August 2009, at 4:45 a.m.
  • 100 islanders logic puzzle
    likesbg -- Friday, 21 August 2009, at 5:16 a.m.
    • 100 islanders logic puzzle
      stw672 -- Friday, 21 August 2009, at 6:28 a.m.
      • 100 islanders logic puzzle
        Havard Raddum -- Friday, 21 August 2009, at 6:36 a.m.
        • 100 islanders logic puzzle
          Elliott Winslow -- Monday, 21 September 2009, at 11:56 a.m.
          • 100 islanders logic puzzle
            Elliott Winslow -- Monday, 21 September 2009, at 11:58 a.m.
            • 100 islanders logic puzzle
              Stein Kulseth -- Monday, 21 September 2009, at 1:17 p.m.
              • 100 islanders logic puzzle
                Fabrice Liardet -- Monday, 21 September 2009, at 1:51 p.m.
  • 100 islanders logic puzzle
    Matt Cohn-Geier -- Friday, 21 August 2009, at 6:06 a.m.
  • 100 islanders logic puzzle
    Havard Raddum -- Friday, 21 August 2009, at 6:32 a.m.
    • 100 islanders logic puzzle
      stw672 -- Friday, 21 August 2009, at 6:39 a.m.
      • 100 islanders logic puzzle
        Fabrice Liardet -- Friday, 21 August 2009, at 7:23 a.m.
  • 100 islanders logic puzzle
    misja -- Friday, 21 August 2009, at 9:18 a.m.
    • 100 islanders logic puzzle
      Tom Keith -- Friday, 21 August 2009, at 1:30 p.m.
      • 100 islanders logic puzzle
        Gregg Cattanach -- Friday, 21 August 2009, at 2:13 p.m.
        • 100 islanders logic puzzle
          Gregg Cattanach -- Friday, 21 August 2009, at 2:16 p.m.
  • 100 islanders logic puzzle
    dc-ohio -- Friday, 21 August 2009, at 12:17 p.m.
  • 100 islanders logic puzzle
    Jon -- Friday, 21 August 2009, at 1:07 p.m.
  • 100 islanders logic puzzle
    bob koca -- Friday, 21 August 2009, at 1:22 p.m.
    • 100 islanders logic puzzle
      Stein Kulseth -- Friday, 21 August 2009, at 2:25 p.m.
      • 100 islanders logic puzzle
        Bob Koca -- Friday, 21 August 2009, at 2:29 p.m.
        • 100 islanders logic puzzle
          misja -- Friday, 21 August 2009, at 2:46 p.m.
        • 100 islanders logic puzzle
          Fabrice Liardet -- Friday, 21 August 2009, at 3:05 p.m.
          • 100 islanders logic puzzle
            Stein Kulseth -- Friday, 21 August 2009, at 3:27 p.m.
        • 100 islanders logic puzzle
          Stein Kulseth -- Friday, 21 August 2009, at 3:13 p.m.
    • 100 islanders logic puzzle
      Tom Keith -- Tuesday, 25 August 2009, at 3:48 p.m.
  • 100 islanders logic puzzle
    Stein Kulseth -- Friday, 21 August 2009, at 2:13 p.m.
  • Don't read unless you want to know the answer...
    trichard -- Friday, 21 August 2009, at 3:02 p.m.
    • Don't read unless you want to know the answer...
      Fabrice Liardet -- Friday, 21 August 2009, at 3:07 p.m.
      • Don't read unless you want to know the answer...
        Rich Munitz -- Saturday, 22 August 2009, at 12:43 a.m.
        • Don't read unless you want to know the answer...
          Bob Koca -- Saturday, 22 August 2009, at 2:01 a.m.
          • Don't read unless you want to know the answer...
            Matt Cohn-Geier -- Saturday, 22 August 2009, at 2:09 a.m.
  • 100 islanders logic puzzle
    David -- Friday, 21 August 2009, at 3:21 p.m.
  • Something Wrong with Puzzle?
    David -- Friday, 21 August 2009, at 4:10 p.m.
    • Something Wrong with Puzzle?
      Fabrice Liardet -- Friday, 21 August 2009, at 5:13 p.m.
  • 100 islanders logic puzzle
    Christian Munk-Christensen -- Friday, 21 August 2009, at 4:56 p.m.
    • 100 islanders logic puzzle
      Gregg Cattanach -- Friday, 21 August 2009, at 5:40 p.m.
      • 100 islanders logic puzzle - what about a silent oracle?
        Gregg Cattanach -- Friday, 21 August 2009, at 5:46 p.m.
        • 100 islanders logic puzzle - what about a silent oracle?
          Steve Mellen -- Friday, 21 August 2009, at 6:15 p.m.
          • What happens after three?
            David -- Friday, 21 August 2009, at 6:41 p.m.
            • What happens after three?
              Gregg Cattanach -- Friday, 21 August 2009, at 6:51 p.m.
            • What happens after three?
              Steve Mellen -- Friday, 21 August 2009, at 7:25 p.m.
          • 100 islanders logic puzzle - what about a silent oracle?
            Ian Shaw -- Monday, 24 August 2009, at 1:00 p.m.
            • 100 islanders logic puzzle - what about a silent oracle?
              Tom Keith -- Monday, 24 August 2009, at 3:59 p.m.
              • 100 islanders logic puzzle - what about a silent oracle?
                Ian Shaw -- Tuesday, 25 August 2009, at 2:09 p.m.
        • 100 islanders logic puzzle - what about a silent oracle?
          Walfinho -- Friday, 21 August 2009, at 6:21 p.m.
      • 100 islanders logic puzzle
        Stein Kulseth -- Monday, 24 August 2009, at 9:45 a.m.
  • 100 islanders logic puzzle
    Jake Jacobs -- Saturday, 22 August 2009, at 2:10 a.m.
  • the really smart guy
    garyo -- Saturday, 22 August 2009, at 4:26 p.m.
  • 100 islanders logic puzzle
    Christian Munk-Christensen -- Monday, 24 August 2009, at 8:29 p.m.
  • 100 islanders logic puzzle
    Joe Russell -- Thursday, 27 August 2009, at 2:11 a.m.
    • 100 islanders logic puzzle
      Gregg Cattanach -- Thursday, 27 August 2009, at 12:25 p.m.
      • 100 islanders logic puzzle
        joe freedman -- Thursday, 27 August 2009, at 6:09 p.m.
        • 100 islanders logic puzzle
          Gregg Cattanach -- Friday, 28 August 2009, at 12:14 p.m.
      • 100 islanders logic puzzle
        Joe Russell -- Friday, 28 August 2009, at 12:51 p.m.