[ducklord]

Who is al?

[asgard1024]

He was a famous Arabic mathematician, a pioneer of algebra and algorithms (both named after him).

(Just kidding. I also didn't know the answer, not having read SICP, this would be my guess, but I believe axblount is right.)

[axblount]

Author lists often end with "et al" which is Latin for "and others."

[lifeformed]

I'm going to name my kid "al Arthur Alexander", so he can claim authorship credit for thousands of writings, and also for millions of highscores in arcade cabinets everywhere.