Strategies for simplifying math expressions

Question

I have a well-formed tree that represents a mathematical expression. For example, given the string: \"1+2-3*4/5\", this gets parsed into:

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Answer 1

You actually can't in general do this because, although they are the same mathematically, the may not be the same in computer arithmetic. For instance, -MAX_INT is undefined, so --%a =/= %a. Similarly for floats, you have to deal with NaN and Inf appropriately.