# Andy's Math/CS page

## Saturday, February 24, 2007

### Define 'Rope'

Random food for thought:

You want to climb to the top of a very tall hanging rope (never mind what's up there). You expect to get tired along the way, too tired to continually grip with your hands. How do you do it?

Gadgets, harnesses, etc. are permissible. I don't have any magically clever solution in mind, only some crude, untested thoughts that for the safety of impressionable youth I'll keep to myself. Also, I asked a friend who says this is a solved problem in rock-climbing circles.

What interested me as I thought about this is how the requirements and mental verification process resembled algorithms work. The climber wants to loop thru a basic routine to create progress ("climb-a-bit"), with a safety invariant ("securely fastened") assumed at the beginning of the routine and reestablished at the end. Efficiency-type considerations also come in play--the amount of rope around the climber's body and the complexity of its arrangement and manipulations should stay bounded.

I've never done engineering, and maybe these analogies are pervasive enough that my observation would seem vacuous to someone in-the-know. Still, it's nice to dabble in problems that have conceptual affinities with math I study without necessarily being reducible to math.

• Yes, I think you just discovered engineering.

Most major universities study these kind of problems just down the hall from the math/CS departments.

By  Anonymous, at 4:00 PM

• So I've heard... but it's such a long hall, and we have our own soda machine at this end, so there you go.

Actually, I did one engineering project in high school--the egg drop. A friend and I built a funky-looking contraption that we told everyone was a 'flying robot'. In fact, it was a remote-control car covered in tin foil, carrying a tub of jello with the egg (jello was what maybe half the class used). We drove it off and the egg survived (but the car didn't).

That should give some idea of my usual level of physical inventiveness and curiosity. Still, I'm trying to change.

By  Andy, at 5:14 PM

• PS. That friend is now the talented young filmmaker Pete Letz, currently trying to break the screenwriting business.

www.peteletz.com

By  Andy, at 7:08 PM

• For what is worth, there is one built-in fallthrough mechanism for when you have no other means of holding to the rope: bite it hard. If you lose consciousness, your jaws will instinctively clench.

Might be a myth, but I vaguely remember hearing that this saved one mountaineer's life some years back.

So, I'd take some good, strong foil to put in my mouth before the world goes black on me. :)

By  Anonymous, at 4:32 PM