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From now on, we are going to use the symbolAlthough it's a little silly to be using two different symbols (ato refer to the same number thatbrefers to.

Would there ever be a situation in which saying "let *a*=*b*" would
be useful and not just silly the way it is here? Yes indeed.
For example, you might be talking about two not-necessarily-related
things *a* and *b*, and in one part of the argument you might want
to think about what happens in the particular case that they happen
to be the same thing. You could use the phrase "let *a*=*b*" to
introduce that part of the argument.

Why don't you go back to the list of steps in the proof and see if you can identify which one is wrong, now that you know it isn't this one?

This page last updated: May 26, 1998

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