Thursday, July 15, 2010

Solution to "Linking rings with scissors"

See the original puzzle

As it turns out, it's actually not too hard to create linked rings.  The first thing my brother tried was to tape the long strip into a knotted loop, and then cut down the middle.    He got two rings, as shown below.

These rings are, technically speaking, linked.  Linked just means that you can't disentangle the rings without breaking them.

But the rings are not simply linked.  There's a particular way to connect the loop in order to get simply linked rings.  The secret is to twist the strip 360 degrees before completing the loop.  And then you cut down the middle.

See spoiler image

Alternatively, you can just create a mobius, and then cut the ring into thirds (or fourths).  This will only result in two rings, and they will be simply linked.

See spoiler image

Additional note of interest: When writing puzzles, I often try to think of a bonus challenge just for the puzzle masters in my audience.  One bonus challenge I considered for this one was to create the Borromean rings by the same method.  But I'm convinced that this challenge is impossible!  Can anyone figure out why?