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Light-bulb Problem


Best Answer BMAD, 10 July 2013 - 08:01 PM

My answer is not very different from BobbyGo's, mainly to recognize two switches light one bulb from each of the two groups, thereby eliminating analysis of some non-occurring cases. It took me awhile to conclude the 1- and 3-switch bulbs were different, then the rest fell quickly in place.

I'll share my BA with BG. ;)

 

 

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16 replies to this topic

#11 BMAD

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Posted 20 June 2013 - 08:18 PM

as stated in the OP:

 

if a switch turns on a light-bulb, that switch must be on to turn it on again

 

so for example....if switch 1 turns on light-bulb A, to turn on light-bulb A again in conjunction with other light bulbs, switch 1 must be in the 'on' position again in conjunction with other switch(es).


Edited by BMAD, 20 June 2013 - 08:19 PM.

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#12 Nins_Leprechaun

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Posted 20 June 2013 - 11:00 PM


Sorry, but does this or doesn't this cover light bulbs that are turned on by 2 switch combos but not 1 switch combos. In other words, for a bulb that is not lit by the 1,2 or 3 switches by themselves but is lit by any 2 switch combo, must both of the switches be on to light this bulb again ie is it necessarly true that the 3 switch combo lights it.

Edited by Nins_Leprechaun, 20 June 2013 - 11:06 PM.

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#13 BMAD

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Posted 20 June 2013 - 11:26 PM

I don't know how to answer your question without giving away the answer.  If you use the previous fact i mentioned, i think you will discover your answer.


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#14 jordge

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Posted 21 June 2013 - 03:59 PM

Spoiler for My thoughts


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#15 bonanova

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Posted 10 July 2013 - 08:49 AM

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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
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#16 bonanova

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Posted 10 July 2013 - 07:59 PM

My answer is not very different from BobbyGo's, mainly to recognize two switches light one bulb from each of the two groups, thereby eliminating analysis of some non-occurring cases. It took me awhile to conclude the 1- and 3-switch bulbs were different, then the rest fell quickly in place.

I'll share my BA with BG. ;)
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#17 BMAD

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Posted 10 July 2013 - 08:01 PM   Best Answer

My answer is not very different from BobbyGo's, mainly to recognize two switches light one bulb from each of the two groups, thereby eliminating analysis of some non-occurring cases. It took me awhile to conclude the 1- and 3-switch bulbs were different, then the rest fell quickly in place.

I'll share my BA with BG. ;)

 

 

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