On a "Theorem" of Peterson

This three-page note gives an example that appears to contradict a theorem in a TOPLAS article by Gary Peterson. Whether or not it does depends on the interpretation of the statement of the theorem, which is given only informally in English. I draw the moral that greater rigor is needed. When I sent this paper to Peterson, he strongly objected to it. I no longer have his message and don’t remember exactly what he wrote, but I think he said that he knew what the correct interpretation was and that I was unfairly suggesting that his theorem might be incorrect. So, I never published this note.