Science Forums 2

[phillip1882]

the halting problem is not saying you can't determine whether a particular program will halt.
its saying there's no universal program to determine whether any program will halt.
let me show you what i mean.

let's say we have the program

x =0
while x <10:
   x = x+1
   x = x-1

and want an algorithm to determine whether or not this program will halt. we note that x goes back and forth between two numbers 0, and 1. so one possible algorithm would be
if x value resets, the program will never halt.
now however consider

y = 0
while x <10:
   y=y+1
   x = 0
   x = y

the x value resets every iteration, but then quickly goes to the value y. so we need a new algorithm. one possible algorithm would be, if x repeats its pattern, the program will never halt.
now consider

y = 0
while x <10:
    y = y+1
    x = 0
    x = 1
    if y = 10:
       x = 11

x repeats its pattern 10 times, yet the program still halts.
in short there is no algorithm that will guarantee an accurate halt detection.