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# Re: [Phys-L] Inference Lab Design

JD's Twelve Coin puzzle reminds me of a box I built many years ago consisting of a Red LED, two D-cells and three rotary SPST on-off switches - all wired in series.

The switches are arranged in a triangle to (correctly) imply no order of precedence but are clearly labeled A, B and C for reasons to be clear later.

The 'puzzle' is to 'flip' the switches enough to make the LED turn on.

The REAL assignment is to figure out and write down an algorithm that will guarantee that the light will light in a minimal number of flips.

Computer literati will quickly figure out the 'Truth Table' approach but many will still be less eager to write out an English paragraph that will let their grandma do the task.

The Box still lies around the 'Lab' at school - five years post-retirement.
Instructions scribbled on the side.
Good to see that it has not yet been relegated to the dust bin.

The D-cells should last a lifetime.

Technical aside - most SPST push buttons have a distinct 'feel' to their on-off states so I recommend finding the 120VAC rotary style at your Home Supply store that avoids this problem.

On Aug 14, 2012, at 1:12 AM, John Denker wrote:

So, how about the Twelve Coins puzzle? It's all about measurement ...
and the optimal solution involves measurements that allow /indirect/
inference of the desired information. There's a lot you can do with
this example. Not all of it needs to be done on Day One; you can
keep spiraling back to it.
http://www.av8n.com/physics/twelve-coins.htm
If this is not suitable, please explain why not.