FIT100
Computers Can’t Debug
There
are some things computers cannot do … and we can prove it!
•No
computer program can tell, give another program P, if P loops forever … halting
prob
•If
possible, it would be handy for debugging
•In
fact, it seems possible … look closely at the program, check the for-statements
(and other
looping structures we didn’t learn)
•Suppose
Loop_Check (P, Q) tests pgm P on input Q, answering “yes/no” to loops
forever