The halting problem says that a Turing machine cannot decide if another Turing machine halts.
However, we know that it is possible to determine if some programs halt. For example, FORTRAN DO statements are simple to formally verify. FORTRAN is however not Turing complete.
What is the largest subset or class of halting programs that can be decided? Is there a class of such languages?
This blog entry seems to hint at the fact that since the compiler optimized the code by eleminating the while(1) loop, Fermat's last theorem is disproved by a compiler.