Talk:Zebra puzzle
Who has the zebra, indeed?
f Firstly, I can't find a solution as stated. The closed I got sastified all but one condition. It could be logic error on my part, but it would help if a list of all properties of all house as solved can be listed here for doublechecking.
- This is an old problem and I've done it by hand. The version I recall was identical except that the missing pet was fish. I had started some time ago to write a task for this as an elaboration of the Dinesman solution and then I put it aside and forgot it - oh well. So I suspect you've missed something. If I recall when I did it by hand I used a matrix to solve it. --Dgamey 04:31, 5 December 2011 (UTC)
- It was a typo on my part, disregard my above comment about no solution; though a listing would still be helpful. --Ledrug 04:41, 5 December 2011 (UTC)
- Maybe an addition to the task description is in order: "Additionally, show the solution for all the houses. Optionally, show the soltion is unique." What do you think? WillNess 11:33, 7 December 2011 (UTC)
- It was a typo on my part, disregard my above comment about no solution; though a listing would still be helpful. --Ledrug 04:41, 5 December 2011 (UTC)
Secondly, the Prolog solution took some shortcuts ("Norwegian in first house" and "Norwegian next to blue house" effectively rolled into one as "the second house is blue"). That's trivial deduction by a person, but it's better to leave the input conditions exactly as stated in the task, to minimize human involvement in this process. --Ledrug 02:19, 5 December 2011 (UTC)
- I noticed that too --Dgamey 04:31, 5 December 2011 (UTC)
- Anything with fewer lines than the number of conditions would seem to me to have been artificially compressed --Dgamey 12:49, 5 December 2011 (UTC)
- I've untangled and fixed that thing with the blue house in the Prolog code now. The rest of shortcuts seems acceptable to me - i.e. the point I wanted to make was about mutually-exclusive choices, like with nationalities - it is a programmer's choice how to write the spec down - whether one by one, or in one list if possible. WillNess 11:33, 7 December 2011 (UTC)
- Anything with fewer lines than the number of conditions would seem to me to have been artificially compressed --Dgamey 12:49, 5 December 2011 (UTC)
I had always known this as the Einstein Logic Puzzle. I suggest a redirect from there to Zebra. --Dgamey 04:31, 5 December 2011 (UTC)
- There seem to be a few names on the WP page. Make as many redirects as you think are necessary. I don't think anyone will confuse it with anything else. --Mwn3d 05:20, 5 December 2011 (UTC)
- Added one for Einstien Logic Puzzle --Dgamey 12:50, 5 December 2011 (UTC)
C# lines
The C# code has lines 190+ chars long. -- Bearophile 18:52, 31 May 2012
FormulaOne
A new addition, but an effective one. A typical characteristic of FormulaOne is the ease with which one can transpose the literal (English) text of the constraints into code: // The Englishman lives in the red house and the Swede has a dog and the Dane drinks tea
houseColour(Englishman) = Red & pet(Swede) = Dog & drinks(Dane) = Tea
Not many (?) languages know this ease of coding. This is chiefly due to the implementation in FormulaOne of the (mathematical) injection -- represented by an indexed array with distinctive elements, the use of relations, and the use of unknown indices. Cf. Example 2.