Wanda: Aristotle was not Belgian, the principle of Buddhism is not “every man for himself”, and the London Underground is not a political movement. Those are all mistakes, Otto. I looked them up.
— A Fish Called Wanda (1988)
When I first heard of hidden Markov chains in mathematics I recall imagining a guy named Markov hiding, Waldo-like, perhaps among chains. While I’ve long passed the point where I can deny knowing what hidden Markov chains are all about — and I ran into an excellent biologically-based overview today — I sometimes get a faint Otto echo when I hear the phrase.