Sure you do and you just did. Knuth wrote a hugely successful typesetting system that is still the standard for mathematical texts. That was one of his accompli

Sure you do and you just did. Knuth wrote a hugely successful typesetting system that is still the standard for mathematical texts. That was one of his accomplishments. I don't know about the others in the article - off the top of my head I can't think of a software system that the others wrote that I have used. But Knuth is a programmer who actually writes code.