A favorite memory of mine is the Sherlock Holmes theater, where the famous detective amazes his friend Watson by capturing criminals using Boolean "two-valued logic" (i.e. Binary logic). I brought along my tape recorder to document the sounds of the drama. Because the action is somewhat difficult to follow on the recording, I have included abridged text captions here, ABOVE each image (beginning with #4).
[Before continuing, I recommend that you study the railroad map next to Watson (Slide #9 gives the best picture). Watson's descriptions and Holmes' "logic" should make more sense.]
W: Holmes! The most astounding affair. The Paddington mob has stolen the Glasgow Express! According to the London switchman, a fellow with an OLIVE mustache, the train left London on time, heading east toward us [at Nye] at full throttle. Of course it never got here. Switchman at Wicket, an amusing GREEN-mustached fellow, reports the train has not passed there, either. I say, Holmes, are you taking notes?
H: No, just checking over my monograph of Boolean two-valued logic, as used in computing machines.
W: The switchman at Babbage-on-Tyne, droll chap with a MOSSY handlebar, said the train DID come to Wicket and went on north toward Glasgow. But Scotland yard can't find it north of Babbage. Seen in London and Babbage, but nowhere else.
H: Now look at this problem as a series of simple true or false statements. True or false, on or off, is or isn’t, right or wrong; this two-sided logic can solve crimes, and a crime solved is a criminal caught. Bye the bye, Watson, turn that railroad switch, will you?
W: I say, that goes onto a dead-end track!
[A train rushes past the station and crashes into a barrier.]
[A squad of policemen rushes across the stage and overcomes the Paddington Mob]
[The mob is carted off to jail.]
H: Clever, disguising themselves as the Southbound Express.
W: Incredible Holmes. How on Earth . . .
H: Let us attack the problem, in much the same way as one would program for an electric computer. What are the facts? Was the London switchman telling the truth?
W: Why, why no! If he had been the train would be HERE [at Nye].
H: FOUR possibilities remain then. (1) Wicket and Babbage told the TRUTH.
W: No, no. If the train did not go through Wicket, it could not reach Babbage.
H: Excellent reasoning, my good Watson. But suppose Wicket were TRUE and Babbage FALSE.
W: Impossible. For if he had not seen the train, WE would have.
H: Was Wicket FALSE and Babbage TRUE?
W: No, for in that case the train would have been seen NORTH of Babbage.
H: Then there is only ONE remaining possibility. All three statements were FALSE, and the Express went WEST from London, passed through Wicket and turned South from Babbage. [And arrived at Nye, as we observed.]
W: Oh, fantastic Holmes! Why, those three railroad men have LIED.
H: Elementary, my dear Watson. Did it not strike you that each of the three was a man with a mustache of a singular GREEN hue?
W: And the leader of the Paddington mob is a man with a green mustache!
H: Correct. I suspect we will have a visitor, shortly. Throw that switch again, will you Watson?
[A handcar carrying a man with a green mustache screeches to a halt. Holmes aims his pistol at the Paddington Mob boss, using his vehicle to race to the various stations, giving false information.]
W: Oh, it’s incredible, Holmes.
Paddington Boss: I dunno. Not if you reduce the problem to simple true or false statements.
W: Dash it Holmes, how do you ever know so much about computers?
IBM Sherlock Holmes.mp3