Yet another excerpt from *The Book of Real and Imaginary Drugs*. I achieved a new high in self promotion.

**The Double Negator**

If you are a geometer, you draw pictures. But what do you do if you are a logician? I guess you can still draw pictures, like proof trees and so on, but these wouldn’t be pictures of the objects you work on. Intuitively, this is obvious. We say “I can draw a triangle.” not “I can draw a triangle picture. ” On the other hand one cannot draw a tautology.

So we have a natural question here: In logic, what is the verb that corresponds to *draw*? I think it is easy to answer this question once we look at some standard terminology in mathematical logic: *sentence, term, syntax, parsing, . . . *As the reader has hopefully guessed, the verb I am talking about is *write.*

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