Just imagine inputting the final character of the last inference step, then waiting for a few minutes while the computer performs incremental compilation of the last few rules. Finally, it emits simply these four characters: "QED."
There was a billionaire in the book Permutation City who uploaded his brain into a supercomputer, then let an optimizer run on it for years. The goal was to get his brain to run in real-time or better, but eventually it spit out an empty file and a log message: "This program produces no output."