Re: Grammar for roman numerals

"whiskey" <alex.habar.nam@gmail.com>
6 Apr 2007 00:00:11 -0400

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From: "whiskey" <alex.habar.nam@gmail.com>
Newsgroups: comp.compilers
Date: 6 Apr 2007 00:00:11 -0400
Organization: Compilers Central
References: 07-03-09507-03-107 07-03-119 07-04-006
Keywords: parse, history

> What about "IXIM"? Intuitively this would be 990 (-(-I+X+I)+M), but it
> might be calculated as (-I+X)+(-I+M) = 1008 as well.


Why (-I+X)+(-I+M) and not -(-I+X)+(-I+M) ? Following the same rule as
before ("a smaller number placed before a larger numeral should be
subtracted from it, instead of added to it") the result will be -(-I+X)
+(-I+M) = -(9)+(999) = 999 - 9 = 990. Since (-I+X) is smaller than (-I
+M), it will be substracted, not added.



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