utility@quiche.cs.mcgill.ca (Ronald BODKIN) (11/22/90)
In article <8839:Nov2100:33:3990@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes: >> main(argc,argv) { >> int I_halt(); >> if (I_halt(argv[0])) { >> while(1); >> } else { >> exit(0); >> } >> } >We are all aware that it is impossible for a fixed algorithm *within* >machine M to solve the halting problem for machine M (provided that M is >not utterly trivial). But the solution takes advantage of a new machine >*outside* M... This is true, and was similar to my "serious answer" to the question. For a humourous(?) one: int I_halt() { int my_pid(); FILE *fp; fp=fopen("/script", "w"); fprintf(fp, "sleep 50\nkill -9 %d\n", my_pid()); system("sh /script &"); return 1; } /* flames about details to /dev/null */