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 Four switches (Posted on 2005-05-09)
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)

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 Subject Author Date re: Solution posted Avin 2006-03-12 20:40:01 Solution posted Tristan 2006-03-12 20:26:03 re(3): AAAAAAAAAAAAAAARGH! Tristan 2006-01-24 13:33:17 re(2): AAAAAAAAAAAAAAARGH! Avin 2006-01-24 09:12:12 re: AAAAAAAAAAAAAAARGH! Tristan 2006-01-24 03:23:20 AAAAAAAAAAAAAAARGH! Avin 2006-01-23 17:29:57 re: Rule Clarification, again Tristan 2006-01-23 14:48:35 Rule Clarification, again Avin 2006-01-23 09:28:14 Further optimization of 3-switch problem (provably minimal) Avin 2006-01-20 08:28:22 re: Trying to build on the 3-switch solution... Tristan 2006-01-20 01:51:06 Trying to build on the 3-switch solution... Avin 2006-01-19 15:47:52 half-spoiler Tristan 2005-11-25 22:02:23 Challenge for Tristan Mindy Rodriguez 2005-11-25 18:38:56 re(2): Model for 3 switch lamp brianjn 2005-07-01 00:22:34 re: Model for 3 switch lamp Tristan 2005-06-30 21:53:46 Model for 3 switch lamp brianjn 2005-06-30 04:29:17 re: solution for 3 and 4 switches problem Tristan 2005-06-09 16:15:29 a more practical approach Eugen 2005-06-09 15:26:25 No Subject Eugen 2005-06-09 09:15:00 solution for 3 and 4 switches problem Eugen 2005-06-08 21:01:10 What I've got so far (3 switch) Avin 2005-05-16 13:58:08 2-Switch Lamp Richard 2005-05-13 21:02:27 re(3): Question Tristan 2005-05-11 23:33:21 re(2): Question Avin 2005-05-11 15:41:43 re: Question Tristan 2005-05-10 21:37:31 Question Avin 2005-05-10 16:28:30 George Boole to the rescue? Erik O. 2005-05-10 15:24:18 First thoughts (for real) TomM 2005-05-10 07:31:16 First thoughts TomM 2005-05-10 02:35:29 I must confess... Tristan 2005-05-09 23:53:18 re(2): the first case - the drawing pcbouhid 2005-05-09 22:39:10 re: the first case - the drawing Erik O. 2005-05-09 22:08:25 the first case - the drawing pcbouhid 2005-05-09 21:06:41 re: the first case (a digitation mistake) pcbouhid 2005-05-09 20:57:06 the first case pcbouhid 2005-05-09 20:53:57 on second thought, I see that it doesn't Charlie 2005-05-09 20:34:07 ??? Is this It? ????? Charlie 2005-05-09 20:27:35

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