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Four switches (Posted on 2005-05-09) Difficulty: 5 of 5
You have two tasks. You must design a 3-switch lamp and a 4-switch lamp. It is recommended that you try the 3-switch lamp first. Your design will include a lightbulb, wires, switches and power sources. The design must follow these rules:

1. You may only use 1 lightbulb for each lamp. The 3-switch lamp can only have one power source, and the 4-switch lamp must have exactly two. You may use any number of wires.
2. Every flip of a switch, no matter the previous positions, must turn the lamp from on to off or off to on.
3. Each wire may connect to any number of switches, power sources, and other wires, and to the lightbulb.
4. Each switch has two separate positions to which wires can connect. If the switch is up, then all the wires connected to position 1 are considered connected to each other. If the switch is down, all the wires connected to position 2 are considered connected to each other.
5. The lightbulb turns on if and only if there exists a complete circuit that includes both the lightbulb and at least one power source.
6. A circuit is a sequence of wires, power sources, and the lightbulb where each is connected to the next item in the sequence (the last is connected to the first). No such sequence may list the same wire, power source, or the lightbulb twice.

I recommend that you denote the different wires with letters like A, B, C, etc.

See The Solution Submitted by Tristan    
Rating: 3.4286 (7 votes)

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re: Solution postedAvin2006-03-12 20:40:01
Solution postedTristan2006-03-12 20:26:03
re(3): AAAAAAAAAAAAAAARGH!Tristan2006-01-24 13:33:17
re(2): AAAAAAAAAAAAAAARGH!Avin2006-01-24 09:12:12
re: AAAAAAAAAAAAAAARGH!Tristan2006-01-24 03:23:20
SolutionAAAAAAAAAAAAAAARGH!Avin2006-01-23 17:29:57
re: Rule Clarification, againTristan2006-01-23 14:48:35
Rule Clarification, againAvin2006-01-23 09:28:14
Some ThoughtsFurther optimization of 3-switch problem (provably minimal)Avin2006-01-20 08:28:22
re: Trying to build on the 3-switch solution...Tristan2006-01-20 01:51:06
Some ThoughtsTrying to build on the 3-switch solution...Avin2006-01-19 15:47:52
Hints/Tipshalf-spoilerTristan2005-11-25 22:02:23
Challenge for TristanMindy Rodriguez2005-11-25 18:38:56
re(2): Model for 3 switch lampbrianjn2005-07-01 00:22:34
re: Model for 3 switch lampTristan2005-06-30 21:53:46
Model for 3 switch lampbrianjn2005-06-30 04:29:17
re: solution for 3 and 4 switches problemTristan2005-06-09 16:15:29
Solutiona more practical approachEugen2005-06-09 15:26:25
No SubjectEugen2005-06-09 09:15:00
Solutionsolution for 3 and 4 switches problemEugen2005-06-08 21:01:10
Some ThoughtsWhat I've got so far (3 switch)Avin2005-05-16 13:58:08
2-Switch LampRichard2005-05-13 21:02:27
Hints/Tipsre(3): QuestionTristan2005-05-11 23:33:21
Questionre(2): QuestionAvin2005-05-11 15:41:43
re: QuestionTristan2005-05-10 21:37:31
QuestionQuestionAvin2005-05-10 16:28:30
Some ThoughtsGeorge Boole to the rescue?Erik O.2005-05-10 15:24:18
First thoughts (for real)TomM2005-05-10 07:31:16
First thoughtsTomM2005-05-10 02:35:29
I must confess...Tristan2005-05-09 23:53:18
re(2): the first case - the drawingpcbouhid2005-05-09 22:39:10
Some Thoughtsre: the first case - the drawingErik O.2005-05-09 22:08:25
the first case - the drawingpcbouhid2005-05-09 21:06:41
Some Thoughtsre: the first case (a digitation mistake)pcbouhid2005-05-09 20:57:06
Some Thoughtsthe first casepcbouhid2005-05-09 20:53:57
on second thought, I see that it doesn'tCharlie2005-05-09 20:34:07
Question??? Is this It? ?????Charlie2005-05-09 20:27:35
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