Conjecture: All odd numbers are prime.

         Mathematician's Proof:
                 3 is prime.  5 is prime.  7 is prime.
                 By induction, all odd numbers are prime.

         Physicist's Proof:
                 3 is prime.  5 is prime.  7 is prime.  9 is experimental
                 error.  11 is prime.  13 is prime ...

         Engineer's Proof:
                 3 is prime.  5 is prime.  7 is prime.  9 is prime.
                 11 is prime.  13 is prime ...

         Computer Scientists's Proof:
                 3 is prime.  3 is prime.  3 is prime.  3 is prime...