July 2013
Intermediate to advanced
282 pages
6h 28m
English
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Building a Simple Proof with a Tree
Truth trees work by creating a contradiction. We take a statement that we want to prove true, turn it around by negating it, and then show that that negation leads to contradictions.
For example, I can use this basic method to prove that there isn’t a largest even number, N:
Example: Prove there is no such thing as a largest even number, N.
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We’ll start by inverting the fact to prove, and then we’ll show that it leads to a contradiction. Suppose that there is a largest even number, N.
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Since N is the largest even number, then for every other even number n, n < N.
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N is a natural number; therefore, it can be added with other natural numbers.
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If we add 2 to N, the result will be even and it will be larger ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.