Comment to the use of parenthesis, so far I've only seen the use of exactly three operators and either zero, one, or two sets of parentheses. Examples:
0 = a+b+c+d
1 = (a+b/c)*d
2 = (a+b)*(c+d)

Also, I do not think that there is a need for nested parentheses since I have not been able to find a formula that require a nested parenthesis and which cannot be rewritten without the need of a nest parenthesis.

For example ((a/b)*c)+d = (a/b*c)+d.
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