Re: Solidus variations

From: Philippe Verdy <>
Date: Tue, 11 Oct 2011 00:35:13 +0200

2011/10/7 Hans Aberg <>:
> On 7 Oct 2011, at 22:22, Murray Sargent wrote:
>> In the linear format of UTN #28, 1/2/3/4 builds up as ((1/2)/3)/4 as in computer languages like C.
> OK. I looked through the paper again, and could not find a description of that.
>> The notation actually started with C semantics and then added a larger set of operators, and finally adopted the full Unicode set of mathematical operators.
> In view of the problems of C semantics, as C++ shows, I am actually reviewing it.

I've seen various interpretations, but the ASCII solidus is
unambiguously used with a strong left-to-right associativity, and the
same occurs in classical mathematics notations (the horizontal bar is
another notation but even where it is used, it also has the equivalent
top-to-bottom associatity).

For me 1/2/3/4 means unambiguously ((1/2)/3)/4, i.e. 1/(2*3*4) when
working with integer, rational, real or complex numbers with an
infinite precision. Yes there are some notations of rationals using an
additive space operator between the integer part and the fractional
part, but it is not meant for being used in maths formulas, but only
in common notations (notably in economy for stocks, or gaming, or some
other pricings), and not in C or C++ or almost all programming

Anyway, programming languages are another piece of text, it is not
really plain-text and most Unicode algorithms do not apply to
programming languages, that have much stricter constraints independant
of what the TUS could attempt to standardize, plus very strong
requirements on the preservation of "legacy" notations that are part
of the lexical and syntaxic definitions of these languages (it is not
tolerated to have multiple interpretations, even if they would seem
more "evident" or intuitive by casual readers: you don't program with
the same freedom in those languages like when you write a humane
Received on Mon Oct 10 2011 - 17:42:30 CDT

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