🚀 go-pugleaf

In article <4279@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes:
> In article <3975:Nov1323:25:4390@kramden.acf.nyu.edu>,
> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
> > Here are two articles about the practical solution to the halting
> > problem.
> The technique referred to is commonly known as "Tortoise and Hare".
> It's a very handy technique for programs that wander around graphs
> and other finite data structures.

Maybe computer science actually hasn't been regressing in Australia.
Thanks for confirming that someone else in the world knows what everyone
knew when the words ``computer science'' sounded funny...

People who aren't familiar with loop detection should look in Knuth,
exercises 3.1-6 and -7 (I think; I don't have the book handy).

  [ Eiffel termination tests ]
> when you write a loop you can provide an expression whose value must decrease
> on each iteration, while remaining non-negative.

You can apply Q's invariants in similar ways.

People who aren't familiar with these techniques should look in Knuth,
chapter 1, the first section on Euclid's algorithm.

---Dan